| 1. |
- Albano, Amanda, et al.
(författare)
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Echocardio-variability - Low and high frequency beat-to-beat variability in echocardiographic signals
- 2013
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Ingår i: Computing in Cardiology 2013. - 9781479908844 ; , s. 767-770
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Konferensbidrag (refereegranskat)abstract
- Measurement signals originating from the cardiovascular system are known to comprise oscillating components and beat-to-beat variability, e.g., heart-rate variability and blood pressure variability. In clinical echocardiographic procedures, typically only a few cardiac cycles are acquired. This pilot study analyses the beat-to-beat variability of echocardiographic variables (echocardio-variability) in minute long acquisitions.
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| 2. |
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| 3. |
- Andersson, Johan, et al.
(författare)
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Male sex pheromone release and female mate choice in a butterfly
- 2007
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 210:6, s. 964-970
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Tidskriftsartikel (refereegranskat)abstract
- In butterflies female mate choice is influenced by both visual and olfactory cues, the latter of which are important at close range. Males of the green-veined butterfly, Pieris napi, are known to release citral ( mixture of geranial and neral, 1: 1), but its role(s) and conditions of release are not known. Here, we show that male P. napi release citral when interacting with conspecific males, conspecific females, heterospecific males and also when alone. The amount of citral released correlated strongly with male flight activity, which explained more than 70% of the variation. This suggests that males do not exercise control over turning release on or off, but rather that citral is emitted as a passive physical process during flight. Electroantennogram experiments showed that female antennal response was ten times more sensitive to citral than male response. Females expressed acceptance behavior when exposed to models made with freshly excised male wings or those treated with citral following chemical extraction, but not to ones with extracted wings only. Hence, these behavioral and electrophysiological tests provide strong evidence that citral is a signal from the male directed to the female during courtship, and that it functions as a male sex pheromone.
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| 4. |
- Antonson, Hans, et al.
(författare)
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Crash Barriers and Driver Behavior : A Simulator Study
- 2013
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Ingår i: Traffic Injury Prevention. - : Informa UK Limited. - 1538-9588 .- 1538-957X. ; 14:8, s. 874-880
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The study examines how drivers experience a conventional W-beam guardrail (metal crash barrier) along both sides of narrow versus wider roads (single carriageway with 2 lanes) in terms of stress, feelings, and driving patterns and whether subjective experience concurs with the actual driving patterns captured by the quantitative data.Methods: The study used different methods to capture data, including the VTI Driving Simulator III (speed and lateral vehicle position) in conjunction with electrocardiogram (ECG) data on heart rate variability (HRV) and questionnaires (oral during driving and written after driving). Eighteen participants-8 men and 10 women-were recruited for the simulator study and the simulator road section was 10 km long.Results: Driving speeds increased slightly on the wider road and on the road with a crash barrier, and the lateral driving position was nearer to the road center on the narrower road and on the road with a crash barrier. The HRV data did not indicate that participants experienced greater stress due to road width or due to the presence of a crash barrier. Participant experience captured in the oral questionnaires suggested that road width did not affect driver stress or driving patterns; however, the written questionnaire results supported the simulator data, indicating that a wider road led to increased speed. None of the participants felt that crash barriers made them feel calmer.Conclusions: We believe that there is a possibility that the increased speed on roads with crash barriers may be explained by drivers’ sense of increased security. This study demonstrates that an experimental design including experience-based data captured using both a simulator and questionnaires is productive. It also demonstrates that driving simulators can be used to study road features such as crash barriers. It seems more than likely that features such as street lamps, signs, and landscape objects could be tested in this way. © 2013 Copyright Taylor and Francis Group, LLC.
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| 5. |
- Antonson, Hans, et al.
(författare)
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Landscape heritage objects' effect on driving : a combined driving simulator and questionnaire study.
- 2014
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Ingår i: Accident Analysis and Prevention. - : Elsevier BV. - 0001-4575 .- 1879-2057. ; 62, s. 168-77
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Tidskriftsartikel (refereegranskat)abstract
- According to the literature, landscape (panoramas, heritage objects e.g. landmarks) affects people in various ways. Data are primarily developed by asking people (interviews, photo sessions, focus groups) about their preferences, but to a lesser degree by measuring how the body reacts to such objects. Personal experience while driving a car through a landscape is even more rare.In this paper we study how different types of objects in the landscape affect drivers during their drive. A high-fidelity moving-base driving simulator was used to measure choice of speed and lateral position in combination with stress (heart rate measure) and eye tracking. The data were supplemented with questionnaires. Eighteen test drivers (8 men and 10 women) with a mean age of 37 were recruited. The test drivers were exposed to different new and old types of landscape objects such as 19th century church, wind turbine, 17th century milestone and bus stop, placed at different distances from the road driven.The findings are in some respect contradictory, but it was concluded that that 33% of the test drivers felt stressed during the drive. All test drivers said that they had felt calm at times during the drive but the reason for this was only to a minor degree connected with old and modern objects. The open landscape was experienced as conducive to acceleration. No significant differences could be observed concerning the test drivers' gaze between old or modern objects, but a significant difference was observed between the test drivers' gaze between road stretches with faraway objects and stretches without objects.
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| 6. |
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| 7. |
- Arvanitis, Leena, et al.
(författare)
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Butterfly seed predation: effects of landscape characteristics, plant ploidy level and population structure
- 2007
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 152:2, s. 275-285
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Tidskriftsartikel (refereegranskat)abstract
- Polyploidization has been suggested as one of the most common mechanisms for plant diversification. It is often associated with changes in several morphological, phenological and ecological plant traits, and therefore has the potential to alter insect–plant interactions. Nevertheless, studies evaluating the effect of plant polyploidy on interspecific interactions are still few. We investigated pre-dispersal seed predation by the butterfly Anthocharis cardamines in 195 populations of two ploidy levels of the herb Cardamine pratensis (tetraploid ssp. pratensis, 2n = 30 vs. octoploid ssp. paludosa, 2n = 56–64). We asked if differences in incidence and intensity of predation among populations were related to landscape characteristics, plant ploidy level and population structure. The incidence of the seed predator increased with increasing plant population size and decreasing distance to nearest population occupied by A. cardamines. The intensity of predation decreased with increasing plant population size and was not affected by isolation. Probability of attack decreased with increasing shading, and intensity of predation was higher in grazed than in non-grazed habitats. The attack intensity increased with increasing mean flower number of plant population, but was not affected by flowering phenology. Individuals in tetraploid populations suffered on average from higher levels of seed predation, had higher mean flower number, were less shaded and occurred more often in grazed habitats than octoploid populations. When accounting for differences in habitat preferences between ploidy levels there was no longer a difference in intensity of predation, suggesting that the observed differences in attack rates among populations of the two ploidy levels are mediated by the habitat. Overall, our results suggest that polyploidization is associated with differentiation in habitat preferences and phenotypic traits leading to differences in interspecific interaction among plant populations. This, in turn, may facilitate further divergence of ploidy levels.
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| 8. |
- Arvanitis, Leena, et al.
(författare)
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Novel antagonistic interactions associated with plant polyploidization influence trait selection and habitat preference.
- 2010
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 13:3, s. 330-7
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Tidskriftsartikel (refereegranskat)abstract
- Polyploidization is an important mechanism for sympatric speciation in plants. Still, we know little about whether plant polyploidization leads to insect host shifts, and if novel interactions influence habitat and trait selection in plants. We investigated herbivory by the flower bud gall-forming midge Dasineura cardaminis on tetraploids and octoploids of the herb Cardamine pratensis. Gall midges attacked only octoploid plant populations, and a transplantation experiment confirmed this preference. Attack rates were higher in populations that were shaded, highly connected or occurred along stream margins. Within populations, late-flowering individuals with many flowers were most attacked. Galling reduced seed production and significantly influenced phenotypic selection on flower number. Our results suggest that an increase in ploidy may lead to insect host shifts and that plant ploidy explains insect host use. In newly formed plant polyploids, novel interactions may alter habitat preferences and trait selection, and influence the further evolution of cytotypes.
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| 9. |
- Arvanitis, Leena, et al.
(författare)
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Plant ploidy level influences selection by butterfly seed predators
- 2008
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Ingår i: Oikos. ; 117, s. 1020-1025
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Tidskriftsartikel (refereegranskat)abstract
- Polyploidization is a common route to plant diversification. Polyploids often differ from their progenitors in size, flower number, flower size and flowering phenology. Such differences may translate into differences in the intensity of interactions with animals. Here we investigated the impact of the ploidy-related differences in tetraploids and octoploids of the perennial herb Cardamine pratensis on pre-dispersal seed predation by the butterfly Anthocharis cardamines. The probability of escaping attack was lower for octoploids than for tetraploids, even after accounting for the fact that octoploids were larger and had fewer flowers than tetraploids. Flower shoot size was correlated with probability of attack in tetraploids but not in octoploids. Differences in plant traits associated with polyploidization can alter interactions with animals, and animal-mediated differences in trait selection between ploidy types can contribute to their further divergence.
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| 10. |
- Arvanitis, Leena, 1959-
(författare)
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Plant polyploidy and interactions with insect herbivores
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Polyploidization has been suggested to be a common mechanism for plant speciation. Polyploidy is associated with changes in plant traits and altered habitat preference. Antagonistic and mutualistic animals are known to discriminate between plants based on variation in such plant traits, suggesting that interactions may have an important role in divergence of plant polyploids after the polyploidization. In this thesis, I investigated the effect of insect herbivores on divergence of plant polyploids in a system consisting of the predispersal seed predator butterfly Anthocharis cardamines, the bud gall forming midge Dasineura cardaminis, and tetraploids and octoploids of the herb Cardamine pratensis. Octoploid populations occurred more often in shaded and nongrazed habitats than tetraploids. Octoploid plants were larger and had fewer but larger flowers than tetraploids. Butterfly attack rates were higher in tetraploid than in octoploid populations, whereas the gall midge attacked only octoploids. These differences were associated with higher abundance of butterflies in sunny habitats and gall midges in shaded habitats. In contrast to the pattern at the population level, octoploid flower shoots were more likely to be attacked by the butterfly in sympatric populations. Also trait selection differed between ploidy levels, both in the absence and in the presence of herbivores. In a field experiment, butterfly preference did not alter the trait selection in tetraploids. In octoploids, the two herbivores did not change selection considered separately. However, their joint effect resulted in significant selection for smaller flower shoots and reduced selection on number of flowers. This thesis demonstrates that differences in habitat preference and phenotypic plant traits between polyploid cytotypes can lead to altered interactions with herbivores. Such differences in interactions with animals may alter not only the relative fitness of cytotypes but also trait selection within the respective ploidy type.
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| 11. |
- Berger, David, et al.
(författare)
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Ecological Constraints on Female Fitness in a Phytophagous Insect
- 2012
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Ingår i: American Naturalist. - : University of Chicago Press. - 0003-0147 .- 1537-5323. ; 180:4, s. 464-480
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Tidskriftsartikel (refereegranskat)abstract
- Although understanding female reproduction is crucial for population demography, determining how and to what relative extent it is constrained by different ecological factors is complicated by difficulties in studying the links between individual behavior, life history, and fitness in nature. We present data on females in a natural population of the butterfly Leptidea sinapis. These data were combined with climate records and laboratory estimates of life-history parameters to predict the relative impact of different ecological constraints on female fitness in the wild. Using simulation models, we partitioned effects of male courtship, host plant availability, and temperature on female fitness. Results of these models indicate that temperature is the most constraining factor on female fitness, followed by host plant availability; the short-term negative effects of male courtship that were detected in the field study were less important in models predicting female reproductive success over the entire life span. In the simulations, females with more reproductive reserves were more limited by the ecological variables. Reproductive physiology and egg-laying behavior were therefore predicted to be co-optimized but reach different optima for females of different body sizes; this prediction is supported by the empirical data. This study thus highlights the need for studying behavioral and life-history variation in orchestration to achieve a more complete picture of both demographic and evolutionary processes in naturally variable and unpredictable environments.
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| 12. |
- Berger, David, et al.
(författare)
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Intraspecific variation in body size and the rate of reproduction in female insects- adaptive allometry or biophysical constraint?
- 2012
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Ingår i: Journal of Animal Ecology. - : Wiley. - 0021-8790 .- 1365-2656. ; 81:6, s. 1244-1258
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Tidskriftsartikel (refereegranskat)abstract
- 1. A high rate of reproduction may be costly if ecological factors limit immediate reproductive output as a fast metabolism compromises own future survival. Individuals with more reserves need more time and opportunity to realize their reproductive potential. Theory therefore predicts that the reproductive rate, defined as the investment in early reproduction in proportion to total potential, should decrease with body size within species. 2. However, metabolic constraints on body size- and temperature-dependent biological rates may impede biophysical adaptation. Furthermore, the sequential manner resources that are allocated to somatic vs. reproductive tissue during ontogeny may, when juveniles develop in unpredictable environments, further contribute to non-adaptive variation in adult reproductive rates. 3. With a model on female egg laying in insects, we demonstrate how variation in body reserves is predicted to affect reproductive rate under different ecological scenarios. Small females always have higher reproductive rates but shorter lifespans. However, incorporation of female host selectivity leads to more similar reproductive rates among female size classes, and oviposition behaviour is predicted to co-evolve with reproductive rate, resulting in small females being more selective in their choice and gaining relatively more from it. 4. We fed simulations with data on the butterfly Pararge aegeria to compare model predictions with reproductive rates of wild butterflies. However, simulated reproductive allometry was a poor predictor of that observed. Instead, reproductive rates were better explained as a product of metabolic constraints on rates of egg maturation, and an empirically derived positive allometry between reproductive potential and size. However, fitness is insensitive to moderate deviations in reproductive rate when oviposition behaviour is allowed to co-evolve in the simulations, suggesting that behavioural compensation may mitigate putative metabolic and developmental constraints. 5. More work is needed to understand how physiology and development together with compensatory behaviours interact in shaping reproductive allometry. Empirical studies should evaluate adaptive hypotheses against proper null hypotheses, including prediction from metabolic theory, preferentially by studying reproductive physiology in combination with behaviour. Conversely, inferences of constraint explanations on reproductive rates must take into consideration that adaptive scenarios may predict similar allometric exponents.
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| 13. |
- Bergman, Martin, et al.
(författare)
-
Contest outcome in a territorial butterfly : the role of motivation
- 2010
-
Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 277:1696, s. 3027-3033
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Tidskriftsartikel (refereegranskat)abstract
- In many butterfly species, males compete over areas advantageous for encountering females. Rules for contest settlement are, however, largely unknown and neither morphological nor physiological traits can reliably predict the contest outcome. Here, we test the hypothesis that contests are settled in accordance with a motivation asymmetry. We staged contests between males of Pararge aegeria and after removing the resident, the non-resident was allowed (i) either to interact with a non-receptive female for 30 min (n = 30) or (ii) to spend 30 min alone in the cage (n = 30), after which the initial resident was reintroduced. The results show that males that had interacted with a female had a higher probability of becoming dominant and reversing contest outcome. Moreover, males that were faster to take over a vacant territory when the resident was removed were more likely to become dominant. Here, we show for the first time, to our knowledge, that frequent encounters with a mated female can increase male motivation to persist in a territorial contest in a butterfly. Further, we suggest that variation in intrinsic motivation reflects male eagerness to take over vacant territory. This study indicates that variation in resource value and motivational asymmetries are important for settling contests in butterflies.
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| 14. |
- Bergman, Martin, et al.
(författare)
-
Differences in mate location behaviours between residents and nonresidents in a territorial butterfly
- 2009
-
Ingår i: Animal Behaviour. - London, England : ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD. - 0003-3472 .- 1095-8282. ; 78:5, s. 1161-1167
-
Tidskriftsartikel (refereegranskat)abstract
- Mate location strategies vary between species. Among butterflies two strategies are recognized: 'patrolling' males spend their life on the wing searching for females and 'perching' males stay at a specific site waiting to intercept passing females. In the speckled wood butterfly, Pararge aegeria, two alternative male strategies have been described: dominant males adopt a perching strategy monopolizing large sunspots on the forest floor, and subdominant males adopt a patrolling strategy. However, comparative analyses have shown that body design differs between perching and patrolling species, hence constraining opportunity for within-species variation in mate location strategy. We tested whether males differ in their propensity to adopt perching or patrolling behaviour by recording time spent flying during 30 min when alone in a large cage with only one large sunspot and many smaller ones, and whether subdominant males adopt a patrolling strategy by allowing dyads of males to interact in the cage for 60 min and recording the same behaviours again. All males adopted perching behaviour when alone, and subdominant males in dyads spent only a short time in extended flights after losing contests over territory ownership, soon returning to a perching strategy and making the best of a bad job from the vantage point of a small sunspot. We argue that previous descriptions of subdominant male P. aegeria adopting a patrolling strategy are based on too short observation periods, and have mistaken males in temporary transit for males adopting patrolling behaviour.
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| 15. |
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| 16. |
- Bergman, Martin, 1981-, et al.
(författare)
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Mate acquisition by females in a butterfly : the effects of mating status and age on female mate-locating behaviour
- 2011
-
Ingår i: Animal Behaviour. - : Elsevier BV. - 0003-3472 .- 1095-8282. ; 81:1, s. 225-229
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Tidskriftsartikel (refereegranskat)abstract
- In most species, female reproductive success is determined by realized fecundity, which depends on the amount of female reproductive reserves and the availability of time for oviposition. Consequently, selection is likely to favour behaviour in virgin females that increases the likelihood of encountering males and thereby minimizing time without sperm. We used the speckled wood butterfly, Pararge aegeria, to test the hypothesis that virgin females increase the probability of encountering males by behaving more conspicuously. We also tested for an effect of age on behaviour, with the prediction that females behave more conspicuously if they remain unmated for a longer period. To do this we conducted controlled behavioural studies in large outdoor cages, comparing the behaviour of young and old, virgin and mated, females. We also assessed the time it took for a male to discover virgin versus mated females. Our results show an effect of age and mating status: old virgin females behaved more conspicuously than young virgin females and mated females, and spent more time in flight and performed more individual flights. Males also discovered virgin females faster than mated females. Furthermore, virgin females did not specifically locate the large sunspot, where perching males are found. Hence, females of P. aegeria adjust their behaviour in accordance with mating status and age, making them more likely to encounter a male and thereby maximize their reproductive success. This study underlines the importance of taking the distribution and behaviour of receptive females into account when studying mate-locating behaviour.
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| 17. |
- Bergman, Martin, et al.
(författare)
-
Mating success of resident versus non-resident males in a territorial butterfly
- 2007
-
Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 274:1618, s. 1659-1665
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Tidskriftsartikel (refereegranskat)abstract
- Male–male competition over territorial ownership suggests that winning is associated with considerable benefits. In the speckled wood butterfly, Pararge aegeria, males fight over sunspot territories on the forest floor; winners gain sole residency of a sunspot, whereas losers patrol the forest in search of females. It is currently not known whether residents experience greater mating success than nonresidents, or whether mating success is contingent on environmental conditions. Here we performed an experiment in which virgin females of P. aegeria were allowed to choose between a resident and a nonresident male in a large enclosure containing one territorial sunspot. Resident males achieved approximately twice as many matings as non-residents, primarily because matings were most often preceded by a female being discovered when flying through a sunspot. There was no evidence that territorial residents were more attractive per se, with females seen to reject them as often as nonresidents. Furthermore, in the cases where females were discovered outside of the sunspot, they were just as likely to mate with non-residents as residents. We hypothesize that the proximate advantage of territory ownership is that light conditions in a large sunspot greatly increase the male’s ability to detect and intercept passing receptive females.
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| 18. |
- Bergman, Martin, et al.
(författare)
-
Territorialitet hos dagfjärilar
- 2011
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Ingår i: Fauna & Flora. ; 106:1, s. 20-25
-
Tidskriftsartikel (populärvet., debatt m.m.)
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| 19. |
- Bergman, Martin, 1981-
(författare)
-
The evolution of territoriality in butterflies
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Competition over mating opportunities is a conspicuous characteristic of animal behaviour. In many butterfly species the males establish territories in places advantageous for encountering females. This thesis addresses questions about how territoriality has evolved and is maintained in butterflies. The studies have been conducted using the speckled wood butterfly, Pararge aegeria, as a model species. Males of P. aegeria are found in sunspots on the forest floor (paper I-V), on the lookout for females visiting the sunspots. However, males are only found in sunspots above a certain size (paper III). This behavior is maintained by a mating success advantage, where using large sunspots instead of small sunspots as perching areas generates a higher reproductive output (paper I). The mating success asymmetry is not explained by female choice or by a female preference for large sunspots per se (paper I, V), but rather the large sunspot facilitates visual performance of perching males and improves flight pursuit and interception of females (paper III). Winners of territorial contests gain sole ownership of large sunspot territories, while losers search for a new suitable sunspot territory (paper I, II & IV) or use smaller, suboptimal sunspots as perching sites (paper II). Territorial contests between P. aegeria males are not settled due to an obvious morphological/physiological asymmetry (paper I). Rather, variation in resource value and motivational asymmetries are important for settling contests (paper IV). A majority of male-female interactions (paper V) and matings (paper I) are initiated by a perching male detecting and intercepting a flying female. Furthermore, females can affect their chances of being detected by a perching male by behaving more conspicuously (paper V). This thesis highlights the role of female behaviour, variation in resource value and motivation asymmetries to understand the evolution of territoriality in butterflies.
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| 20. |
- Bergman, Martin, et al.
(författare)
-
Visual mate detection and mate flight pursuit in relation to sunspot size in a woodland territorial butterfly
- 2009
-
Ingår i: Animal Behaviour. - London, England : ACADEMIC PRESS LTD- ELSEVIER SCIENCE LT. - 0003-3472 .- 1095-8282. ; 78:1, s. 17-23
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Tidskriftsartikel (refereegranskat)abstract
- Territory residency is associated with considerable benefits. In the speckled wood butterfly, Pararge aegeria, males fight over ownership of large sunspots in open forest habitats; winners become sunspot residents, and losers become nonterritorial and sit and wait for females in small sunspots. A previous study has shown that residents have higher mating success than nonterritorial males, although females are not more attracted to territorial males or sunspot territories per se. Here we tested the hypotheses (1) that the higher success of resident males is caused by visual mate detection being more efficient in a large than in a small sunspot, and (2) that only sunspots above a certain size are defended as territories. Field assessment of territorial sunspot size showed that defended sunspots were significantly larger than 'average sunspots' on the forest floor. Experimental tests of male ability to detect visually a model butterfly passing through a sunspot showed that males were more successful in pursuing and intercepting a passing model when. own a longer distance in the sunspot. Hence, we conclude that light conditions and associated visual mate detection and ability to complete mate flight pursuit can explain why P. aegeria males defend territories in large sunspots in forest habitats.
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| 21. |
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| 22. |
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| 23. |
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| 24. |
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| 25. |
- Bergström, Jonas, et al.
(författare)
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No effect of male courtship intensity on female remating in the butterfly Pieris napi.
- 2005
-
Ingår i: Journal of insect behavior. - 0892-7553 .- 1572-8889. ; 18:4, s. 479-489
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Tidskriftsartikel (refereegranskat)abstract
- In Pieris napi, female fitness increases with number of matings, but wild females mate at an unexpectedly low rate. From a sexual conflict perspective this could be because males manipulate female remating, or alternatively, because wild females experience costs associated with remating which are not applicable under laboratory conditions. To get an indication which sex controls remating and/or the different sexes’ relative costs and benefits of remating, we here test whether female mating frequency is affected by male courtship intensity. We found no effect on female mating frequency or lifespan. This indicates that (i) females control remating and their optimal mating frequency is lower compared to males, or (ii) males can manipulate female remating. We argue that both these alternatives may apply simultaneously to P. napiand that they are inseparable.
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| 26. |
- Bergström, Jonas, 1970-
(författare)
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The evolution of mating rates in Pieris napi
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the green-veined white butterfly (Pieris napi), females obtain direct fitness benefits from mating multiply and studies have shown that fitness increases seemingly monotonically with number of matings. The reason is that at mating males transfer a large nutritious gift (a so called nuptial gift) to the females that the females use to increase both their fecundity and lifespan. In addition, if exposed to poor food conditions as larvae, females mature at a smaller size compared to males. Accordingly, it was suggested that smaller females could compensate for their size through nuptial feeding by, for instance, mating more frequently. We did not find any support for that hypothesis. On the contrary, larger females remated sooner and had a higher lifetime number of matings. Neither were smaller females able to compensate in any other way, because singly mated females and multiply mated females suffered to the same extent from their smaller size. This thesis also shows that despite the positive relationship between fitness and number of matings, there is a large variation in female mating frequency in wild populations and about every second female mates only once or twice. This variation is not dependent on how often females get courted by males, because female mating frequency was shown not to be affected by male courtship intensity. Hence, the reason for the low mating frequency could either be that males have evolved the ability to manipulate females to mate at a suboptimal rate as a measure of protection against sperm competition, or alternatively, that female mating rate is suppressed by some costs. Using two selection lines, artificially selected for either a high or a low mating rate, we showed that the variation in mating rate was mainly a female trait because which line the females were from affected their mating rate whereas which line the male was from did not. This implies that females mate at a low rate due to hidden costs or due to constraints. The same study also showed that females with a high "intrinsic" mating rate lived shorter, but only when denied remating. This led us to test the hypothesis that the cost females face is to have the ability to mate at a high rate but the cost is only paid when remating opportunities are scarce. However, we found no support for such an idea, because females with a high intrinsic mating rate held in a cold environment where the butterflies were prevented from flying and feeding did not live shorter. Neither was there an effect of a female’s mating rate on her ability to quickly break down and convert male nutrient gifts into egg material. Female mating rate did, on the other hand, affect dispersal tendency, with low mating rate females being more inclined to fly between different habitats. The underlying reason for this is still to be explored.
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| 27. |
- Bijl, Wouter, et al.
(författare)
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Butterfly dichromatism primarily evolved via Darwin's, not Wallace's, model
- 2020
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Ingår i: Evolution letters. - : Oxford University Press (OUP). - 2056-3744. ; 4:6, s. 545-555
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Tidskriftsartikel (refereegranskat)abstract
- Sexual dimorphism is typically thought to result from sexual selection for elaborated male traits, as proposed by Darwin. However, natural selection could reduce expression of elaborated traits in females, as proposed by Wallace. Darwin and Wallace debated the origins of dichromatism in birds and butterflies, and although evidence in birds is roughly equal, if not in favor of Wallace's model, butterflies lack a similar scale of study. Here, we present a large‐scale comparative phylogenetic analysis of the evolution of butterfly coloration, using all European non‐hesperiid butterfly species (n = 369). We modeled evolutionary changes in coloration for each species and sex along their phylogeny, thereby estimating the rate and direction of evolution in three‐dimensional color space using a novel implementation of phylogenetic ridge regression. We show that male coloration evolved faster than female coloration, especially in strongly dichromatic clades, with male contribution to changes in dichromatism roughly twice that of females. These patterns are consistent with a classic Darwinian model of dichromatism via sexual selection on male coloration, suggesting this model was the dominant driver of dichromatism in European butterflies.
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| 28. |
- Björck van Dijken, Christina, et al.
(författare)
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Low back pain, lifestyle factors and physical activity: a population-based study.
- 2008
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Ingår i: Journal of Rehabilitation Medicine. - : Medical Journals Sweden AB. - 1650-1977 .- 1651-2081. ; 40:10, s. 864-869
-
Tidskriftsartikel (refereegranskat)abstract
- Objective and designThe prevalence of low back pain was assessed in relation to physical activity, for both work and leisure activities, in a randomly selected population in the northern part of Sweden. Additionally, the associations between age, sex, level of education, lifestyle factors, demographic characteristics, and low back pain were evaluated. Subjects: A total of 5798 subjects aged 25–79 years were selected randomly from a geographically well-defined area in northern Sweden. Methods: Additional questions concerning people's experience of low back pain were added to the questionnaire of the World Health Organization MONICA (MONItoring of trends and determinants in CArdiovascular disease) health survey with the aim of investigating prevalence rates and factors associated with low back pain. Results: Forty-one percent of the participants reported having low back pain (of these 55% were women and 45% men). The prevalence rate was highest in the age group 55–64 years. Chronic low back pain was the most frequent occurring problem. Of those with low back pain, 43% of the women and 37% of the men reported having continuous low back pain for more than 6 months. Individuals with low back pain often experienced a more physically heavy workload at work and lower physical activity during leisure time, and they were also more likely to have been smokers, have had higher body mass index, lived in smaller communities, and were less educated than people without low back pain. Conclusion: Low back pain seems to be associated with physical activity at work and in leisure time, certain lifestyle factors and demographic characteristics.
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| 29. |
- Blanckenhorn, Wolf U, et al.
(författare)
-
Proximate causes of Rensch's rule : Does sexual size dimorphism in arthropods result from sex differences in development time?
- 2007
-
Ingår i: American Naturalist. ; 169:2, s. 245-257
-
Tidskriftsartikel (refereegranskat)abstract
- A prominent interspecific pattern of sexual size dimorphism (SSD) is Rensch's rule, according to which male body size is more variable or evolutionarily divergent than female body size. Assuming equal growth rates of males and females, SSD would be entirely mediated, and Rensch's rule proximately caused, by sexual differences in development times, or sexual bimaturism (SBM), with the larger sex developing for a proportionately longer time. Only a subset of the seven arthropod groups investigated in this study exhibits Rensch's rule. Furthermore, we found only a weak positive relationship between SSD and SBM overall, suggesting that growth rate differences between the sexes are more important than development time differences in proximately mediating SSD in a wide but by no means comprehensive range of arthropod taxa. Except when protandry is of selective advantage ( as in many butterflies, Hymenoptera, and spiders), male development time was equal to ( in water striders and beetles) or even longer than ( in drosophilid and sepsid flies) that of females. Because all taxa show female-biased SSD, this implies faster growth of females in general, a pattern markedly different from that of primates and birds (analyzed here for comparison). We discuss three potential explanations for this pattern based on life-history trade-offs and sexual selection.
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| 30. |
- Boman, Jesper, et al.
(författare)
-
Evolution of hybrid inviability associated with chromosome fusions
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Chromosomal rearrangements, such as inversions, have received considerable attention in the speciation literature due to their hampering effects on recombination. However, less is known about how other rearrangements, such as chromosome fissions and fusions, can affect the evolution of reproductive isolation. Here, we used crosses between populations of the wood white butterfly (Leptidea sinapis) with different karyotypes to identify genomic regions associated with hybrid inviability. We mapped candidate loci for hybrid inviability by contrasting allele frequencies between F2 hybrids that survived until the adult stage with individuals of the same cohort that succumbed to hybrid incompatibilities. Hybrid inviability factors were predominantly found in fast-evolving regions with reduced recombination rates, especially in regions where chromosome fusions have occurred. By analyzing sequencing coverage, we excluded aneuploidies as a direct link between hybrid inviability and chromosome fusions. Instead, our results point to an indirect relationship between hybrid inviability and chromosome fusions, possibly related to reductions in recombination rate caused by fusions. These results highlight that the extensive variation in chromosome numbers observed across the tree of life does not only distinguish species but can also be involved in speciation by being hotspots for the early evolution of postzygotic reproductive isolation.
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| 31. |
- Boman, Jesper, et al.
(författare)
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Meiotic drive against chromosome fusions in butterfly hybrids
- 2024
-
Ingår i: Chromosome Research. - : Springer. - 0967-3849 .- 1573-6849. ; 32:2
-
Tidskriftsartikel (refereegranskat)abstract
- Species frequently differ in the number and structure of chromosomes they harbor, but individuals that are heterozygous for chromosomal rearrangements may suffer from reduced fitness. Chromosomal rearrangements like fissions and fusions can hence serve as a mechanism for speciation between incipient lineages, but their evolution poses a paradox. How can rearrangements get fixed between populations if heterozygotes have reduced fitness? One solution is that this process predominantly occurs in small and isolated populations, where genetic drift can override natural selection. However, fixation is also more likely if a novel rearrangement is favored by a transmission bias, such as meiotic drive. Here, we investigate chromosomal transmission distortion in hybrids between two wood white (Leptidea sinapis) butterfly populations with extensive karyotype differences. Using data from two different crossing experiments, we uncover that there is a transmission bias favoring the ancestral chromosomal state for derived fusions, a result that shows that chromosome fusions actually can fix in populations despite being counteracted by meiotic drive. This means that meiotic drive not only can promote runaway chromosome number evolution and speciation, but also that it can be a conservative force acting against karyotypic change and the evolution of reproductive isolation. Based on our results, we suggest a mechanistic model for why chromosome fusion mutations may be opposed by meiotic drive and discuss factors contributing to karyotype evolution in Lepidoptera.
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| 32. |
- Bresell, Anders, et al.
(författare)
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Bioinformatic and enzymatic characterization of the MAPEG superfamily
- 2005
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Ingår i: The FEBS Journal. - : Wiley. - 1742-464X .- 1742-4658. ; 272:7, s. 1688-1703
-
Tidskriftsartikel (refereegranskat)abstract
- The membrane associated proteins in eicosanoid and glutathione metabolism (MAPEG) superfamily includes structurally related membrane proteins with diverse functions of widespread origin. A total of 136 proteins belonging to the MAPEG superfamily were found in database and genome screenings. The members were found in prokaryotes and eukaryotes, but not in any archaeal organism. Multiple sequence alignments and calculations of evolutionary trees revealed a clear subdivision of the eukaryotic MAPEG members, corresponding to the six families of microsomal glutathione transferases (MGST) 1, 2 and 3, leukotriene C4 synthase (LTC4), 5-lipoxygenase activating protein (FLAP), and prostaglandin E synthase. Prokaryotes contain at least two distinct potential ancestral subfamilies, of which one is unique, whereas the other most closely resembles enzymes that belong to the MGST2/FLAP/LTC4 synthase families. The insect members are most similar to MGST1/prostaglandin E synthase. With the new data available, we observe that fish enzymes are present in all six families, showing an early origin for MAPEG family differentiation. Thus, the evolutionary origins and relationships of the MAPEG superfamily can be defined, including distinct sequence patterns characteristic for each of the subfamilies. We have further investigated and functionally characterized representative gene products from Escherichia coli, Synechocystis sp., Arabidopsis thaliana and Drosophila melanogaster, and the fish liver enzyme, purified from pike (Esox lucius). Protein overexpression and enzyme activity analysis demonstrated that all proteins catalyzed the conjugation of 1-chloro-2,4-dinitrobenzene with reduced glutathione. The E. coli protein displayed glutathione transferase activity of 0.11 µmol·min−1·mg−1 in the membrane fraction from bacteria overexpressing the protein. Partial purification of the Synechocystis sp. protein yielded an enzyme of the expected molecular mass and an N-terminal amino acid sequence that was at least 50% pure, with a specific activity towards 1-chloro-2,4-dinitrobenzene of 11 µmol·min−1·mg−1. Yeast microsomes expressing the Arabidopsis enzyme showed an activity of 0.02 µmol·min−1·mg−1, whereas the Drosophila enzyme expressed in E. coli was highly active at 3.6 µmol·min−1·mg−1. The purified pike enzyme is the most active MGST described so far with a specific activity of 285 µmol·min−1·mg−1. Drosophila and pike enzymes also displayed glutathione peroxidase activity towards cumene hydroperoxide (0.4 and 2.2 µmol·min−1·mg−1, respectively). Glutathione transferase activity can thus be regarded as a common denominator for a majority of MAPEG members throughout the kingdoms of life whereas glutathione peroxidase activity occurs in representatives from the MGST1, 2 and 3 and PGES subfamilies.
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| 33. |
- Brändström, Sture, et al.
(författare)
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Developing distance music education in arctic Scandinavia : electric guitar teaching and master classes
- 2012
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Ingår i: Music Education Research. - : Informa UK Limited. - 1461-3808 .- 1469-9893. ; 14:4, s. 448-456
-
Tidskriftsartikel (refereegranskat)abstract
- The purpose of this article was to present the project Vi r Music, with a focus on electric guitar teaching (Case 1) and master classes (Case 2). What were the benefits and shortcomings in the two cases and how did online teaching differ from face-to-face teaching? A guitar teacher with a specialisation in jazz music introduced distance teaching to three of his students. Under supervision the students taught upper-secondary students living 290 km from the university. The guitar lessons were held with the use of Skype. In the project, 11 distance master classes were also studied. The devices used were a video-conference system, external microphones and speakers, and 50–52′′ TV screens. The methods for data collection in both cases were above all qualitative interviews with teachers and students and to some degree observation of the teaching sessions. The overall impression from the study was that teachers and students seemed to consider the online teaching in the project a positive experience. The informants looked upon the distance-learning situation as a fruitful complement to face-to-face teaching. Because of the time delay, the most difficult part of the online teaching was playing together or marking the rhythm. The results suggested that video-conference teaching is more intensive than face-to-face teaching and requires both thorough planning and readiness to improvise during the lesson.
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| 34. |
- Brändström, Sture, et al.
(författare)
-
Distance Music Education in Northern Europe
- 2010
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The name of the project we are going to present is Vi r Music (www.vi-r-music.blogspot.com/). The aim of the project is to create a network that will start researching the possibilities for virtual music education at different levels. The Swedish part of the project consists of masterclasses, electric guitar tuition and vocal tuition. Some preliminary results: In distance education there are several technical equipments added to the traditional music education context. We have found that 30 minutes lessons are optimal concerning distance tuition. Try to use rooms with calm visual backgrounds and without too much echo.
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| 35. |
- Brändström, Sture, et al.
(författare)
-
The relevance of distributed master classes
- 2011
-
Ingår i: Musik och kunskapsbildning. - Göteborg : Konstnärliga fakulteten Göteborgs universitet. - 9789197847629 ; , s. 39-47
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 36. |
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| 37. |
- Brändström, Sture, et al.
(författare)
-
Två musikpedagogiska fält : en studie om kommunal musikskola och musiklärarutbildning
- 1995
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The thesis consists of two parts. One is directed towards municipal music schools, and one deals with music teacher education at university level. The purpose was to investigate the recruitment to these two educations, and to describe and explain how different student groups perceived and used their education. Five empirical studies have been accomplished, and central questions were: which deliberate and non-deliberate choices of musical activities are made by children and music students, and how are these choices affected by socio-economical, geographical and gender prerequisites.Theoretically, the first part of the thesis was based on the educational sociology of Pierre Bourdieu and on previous empirical studies in music pedagogy. The first empirical study was directed towards the recruitment of pupils to the municipal music school in Piteå (n=1085). The study showed that two out of three pupils are girls. Furthermore, it was twice as common among children of higher employees and university graduates to study at the music school than among children with working class backgrounds. The second empirical study was an interview with children, 12-13 years of age (n=369). The results indicated that boys and girls understand and use music and music education in significantly different ways. Furthermore, differences related to socioeconomic background, musical background and residential area were also shown.The second part of the thesis begins with a summary of the origin and scientific basis of Swedish music pedagogy, followed by an investigation regarding recruitment to the music teacher education at the School of Music in Piteå (n=177). The investigation indicated that recruitment is socially biased, similar to that of the municipal music school. One third of the music teacher students were recruited from families where one of the parents worked as a teacher. One out of three students came from homes where religion was an important part of family life. In an interview-study with 60 music teacher students, differences related to gender and educational orientation arose in how students looked upon and used their education. The study showed two attitudes to music and music education, which were linked to the following concepts: musician code and teacher code. In connection with these concepts, three action strategies could be identified: navigation, revolt, and adjustment. These strategies were interpreted as an expression of the tension between the demands of the education and the individuals' wish to have his or her interests and needs met. The dissertation concludes with a project called "Self-formulated goals and self-evaluation in music education" and a short forward-looking discussion pertaining to questions that have been generated throughout the entire research process.
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| 38. |
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| 39. |
- Cassel, Anna, et al.
(författare)
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Effects of population size and food stress on fitness-related characters in the scarce heath, a rare butterfly in Western Europe
- 2001
-
Ingår i: Conservation Biology. - : Blackwell Science Publishing. - 0888-8892 .- 1523-1739. ; 15:6, s. 1667-1673
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract: Knowledge about the effects of inbreeding in natural populations is scarce, especially in invertebrates. We analyzed to what extent fitness-related traits in the scarce heath ( Coenonympha hero), a butterfly, are affected by population size and isolation and whether differences in food quality influence these effects. We categorized nine populations as either large or small and isolated. Full-sib groups of offspring from 27 females were followed under seminatural conditions. Because of increased zygote mortality, egg hatchability was significantly lower in the small and isolated populations than in the large ones. Population category had no effect on larval weight under optimal conditions, but weight was significantly lower in the small-isolated category with low food quality. The effects of inbreeding can thus be hidden when conditions are benign but can appear under stress. Survival also differed significantly between population categories, and larval developmental time tended to be longer in the small-isolated category, irrespective of food conditions. We suggest that the differences in fitness between offspring from large and small isolated populations are at least partly due to inbreeding. This adds a further threat to a species that is already suffering from decreasing population sizes and increasing isolation among populations.
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| 40. |
- Dinca, Vlad, et al.
(författare)
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Reproductive isolation and patterns of genetic differentiation in a cryptic butterfly species complex
- 2013
-
Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 26:10, s. 2095-2106
-
Tidskriftsartikel (refereegranskat)abstract
- Molecular studies of natural populations are often designed to detect and categorize hidden layers of cryptic diversity, and an emerging pattern suggests that cryptic species are more common and more widely distributed than previously thought. However, these studies are often decoupled from ecological and behavioural studies of species divergence. Thus, the mechanisms by which the cryptic diversity is distributed and maintained across large spatial scales are often unknown. In 1988, it was discovered that the common Eurasian Wood White butterfly consisted of two species (Leptidea sinapis and Leptidea reali), and the pair became an emerging model for the study of speciation and chromosomal evolution. In 2011, the existence of a third cryptic species (Leptidea juvernica) was proposed. This unexpected discovery raises questions about the mechanisms preventing gene flow and about the potential existence of additional species hidden in the complex. Here, we compare patterns of genetic divergence across western Eurasia in an extensive data set of mitochondrial and nuclear DNA sequences with behavioural data on inter- and intraspecific reproductive isolation in courtship experiments. We show that three species exist in accordance with both the phylogenetic and biological species concepts and that additional hidden diversity is unlikely to occur in Europe. The Leptidea species are now the best studied cryptic complex of butterflies in Europe and a promising model system for understanding the formation of cryptic species and the roles of local processes, colonization patterns and heterospecific interactions for ecological and evolutionary divergence.
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| 41. |
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| 42. |
- Ekström, Magnus, et al.
(författare)
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Oral corticosteroid use, morbidity and mortality in asthma: A nationwide prospective cohort study in Sweden
- 2019
-
Ingår i: Allergy: European Journal of Allergy and Clinical Immunology. - : Wiley. - 0105-4538 .- 1398-9995. ; 74:11, s. 2181-2190
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Patterns and determinants of long-term oral corticosteroid (OCS) use in asthma and related morbidity and mortality are not well-described. In a nationwide asthma cohort in Sweden, we evaluated the patterns and determinants of OCS use and risks of OCS-related morbidities and mortality. Methods: Data for 217993 asthma patients (aged≥6years) in secondary care were identified between 2007 and 2014 using Swedish national health registries. OCS use at baseline was categorized: regular users (≥5mg/d/y; n=3299; 1.5%); periodic users (>0 but <5mg/d/y; n=49930; 22.9%); and nonusers (0mg/d/y; n=164765; 75.6%). Relative risks of becoming a regular OCS user and for morbidity and mortality were analysed using multivariable Cox regression. Results: At baseline, 24% of asthma patients had used OCS during the last year and 1.5% were regular users. Of those not using OCS at baseline, 26% collected at least one OCS prescription and 1.3% became regular OCS users for at least 1year during the median follow-up of 5.3years. Age at asthma diagnosis, increasing GINA severity and Charlson Comorbidity Index were associated with regular OCS use. Compared to periodic and non-OCS use, regular use was associated with increased incidence of OCS-related morbidities and greater all-cause mortality, adjusted HR 1.34 (95% CI 1.24-1.45). Conclusions: Oral corticosteroids use is frequent for asthma patients, and many are regular users. Regular OCS use is associated with increased risk of morbidity and mortality. These findings indicate that there is a need of other treatment options for patients with severe asthma who are using regular OCS. © 2019 The Authors Allergy Published by John Wiley & Sons Ltd
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| 43. |
- Ekström, Magnus, et al.
(författare)
-
Risk of Rehospitalization and Death in Patients Hospitalized Due to Asthma
- 2021
-
Ingår i: Journal of Allergy and Clinical Immunology: In Practice. - : Elsevier BV. - 2213-2198 .- 2213-2201. ; 9:5
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Asthma is a heterogeneous inflammatory airway disease that continues to cause considerable morbidity across the world, with poor asthma control leading to hospitalizations. Objective: The present study investigated the risk of rehospitalization, mortality, and the management of patients with asthma who had been hospitalized because of an asthma exacerbation. Methods: National Swedish health registries were linked for patients 6 years or older who were admitted to hospital because of asthma (index date) between January 1, 2006, and December 31, 2015. Exacerbations were defined as asthma-related hospitalization, emergency visits, or collection of oral steroids. Patients were followed for rehospitalizations 12 months after the index date, health care resource utilization and treatment for 36 months, and mortality to study end. Regression models for time-to-event analyses were applied to assess risk factors for rehospitalization and mortality. Results: A total of 15,691 patients (mean age, 51.5 years; 63% females) were included, of whom 1,892 (12%) were rehospitalized for asthma within 12 months. Rehospitalized patients had a markedly increased risk of subsequent asthma-related mortality (adjusted hazard ratio, 2.80; 95% CI, 1.95-4.01) compared with those not rehospitalized. Two-third of the patients were not followed up by a hospital-based specialist, and 60% did not collect enough inhaled corticosteroid doses to cover daily treatment the year postindex. Conclusions: In this study, more than 1 in 10 patients were rehospitalized because of asthma within 12 months, and rehospitalizations were associated with asthma-related mortality. Few patients were seen by a hospital-based specialist, and few used inhaled corticosteroid continuously. Closer monitoring after hospitalization is needed. © 2020 The Authors
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| 44. |
- Esperk, Toomas, et al.
(författare)
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Distinguishing between anticipatory and responsive plasticity in a seasonally polyphenic butterfly
- 2013
-
Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477. ; 27:2, s. 315-332
-
Tidskriftsartikel (refereegranskat)abstract
- Seasonal generations of short-lived organisms often differ in their morphological, behavioural and life history traits, including body size. These differences may be either due to immediate effects of seasonally variable environment on organisms (responsive plasticity) or rely on presumably adaptive responses of organisms to cues signalizing forthcoming seasonal changes (anticipatory plasticity). When directly developing individuals of insects are larger than their overwintering conspecifics, the between-generation differences are typically ascribed to responsive plasticity in larval growth. We tested this hypothesis using the papilionid butterly Iphiclides podalirius as a model species. In laboratory experiments, we demonstrated that seasonal differences in food quality could not explain the observed size difference. Similarly, the size differences are not likely to be explained by the immediate effects of ambient temperature and photoperiod on larval growth. The qualitative pattern of natural size differences between the directly developing and diapausing butterflies could be reproduced in the laboratory as a response to photoperiod, indicating anticipatory character of the response. Directly developing and diapausing individuals followed an identical growth trajectory until the end of the last larval instar, with size differences appearing just a few days before pupation. Taken together, various lines of evidence suggest that between-generation size differences in I. podalirius are not caused by immediate effects of environmental factors on larval growth. Instead, these differences rather represent anticipatory plasticity and are thus likely to have an adaptive explanation. It remains currently unclear, whether the seasonal differences in adult size per se are adaptive, or if they constitute co-product of processes related to the diapause. Our study shows that it may be feasible to distinguish between different types of plasticity on the basis of empirical data even if fitness cannot be directly measured, and contributes to the emerging view about the predominantly adaptive nature of seasonal polyphenisms in insects.
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| 45. |
- Fogelström, Elsa, et al.
(författare)
-
Plant-herbivore synchrony and selection on plant flowering phenology
- 2017
-
Ingår i: Ecology. - : Wiley. - 0012-9658 .- 1939-9170. ; 98:3, s. 703-711
-
Tidskriftsartikel (refereegranskat)abstract
- Temporal variation in natural selection has profound effects on the evolutionary trajectories of populations. One potential source of variation in selection is that differences in thermal reaction norms and temperature influence the relative phenology of interacting species. We manipulated the phenology of the butterfly herbivore Anthocharis cardamines relative to genetically identical populations of its host plant, Cardamine pratensis, and examined the effects on butterfly preferences and selection acting on the host plant. We found that butterflies preferred plants at an intermediate flowering stage, regardless of the timing of butterfly flight relative to flowering onset of the population. Consequently, the probability that plant genotypes differing in timing of flowering should experience a butterfly attack depended strongly on relative phenology. These results suggest that differences in spring temperature influence the direction of herbivore-mediated selection on flowering phenology, and that climatic conditions can influence natural selection also when phenotypic preferences remain constant.
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| 46. |
- Friberg, Magne, et al.
(författare)
-
Asymmetric life-history decision-making in butterfly larvae
- 2011
-
Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 165:2, s. 301-310
-
Tidskriftsartikel (refereegranskat)abstract
- In temperate environments, insects appearing in several generations in the growth season typically have to decide during the larval period whether to develop into adulthood, or to postpone adult emergence until next season by entering a species-specific diapause stage. This decision is typically guided by environmental cues experienced during development. An early decision makes it possible to adjust growth rate, which would allow the growing larva to respond to time stress involved in direct development, whereas a last-minute decision would instead allow the larva to use up-to-date information about which developmental pathway is the most favourable under the current circumstances. We study the timing of the larval pathway decision-making between entering pupal winter diapause and direct development in three distantly related butterflies (Pieris napi, Araschnia levana and Pararge aegeria). We pinpoint the timing of the larval diapause decision by transferring larvae from first to last instars from long daylength (inducing direct development) to short daylength conditions (inducing diapause), and vice versa. Results show that the pathway decision is typically made in the late instars in all three species, and that the ability to switch developmental pathway late in juvenile life is conditional; larvae more freely switched from diapause to direct development than in the opposite direction. We contend that this asymmetry is influenced by the additional physiological preparations needed to survive the long and cold winter period, and that the reluctance to make a late decision to enter diapause has the potential to be a general trait among temperate insects.
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| 47. |
- Friberg, Magne, et al.
(författare)
-
Autumn mass change and winter mass loss differ between migratory and nonmigratory butterflies
- 2023
-
Ingår i: Animal Behaviour. - 0003-3472 .- 1095-8282. ; 204, s. 67-75
-
Tidskriftsartikel (refereegranskat)abstract
- Poikilotherms have two major alternative strategies to deal with the inhospitable conditions of temperate winters: hibernation or migration. The vast majority of insects spend winter in a speciesspecific diapause resting stage, while others remain reproductively active after having migrated to more hospitable environments in the autumn. The butterfly clade Nymphalini offers an interesting possibility for comparisons among species adopting different strategies. Whereas most genera in this clade have evolved adult diapause, species in the genus Vanessa engage in an annual multigeneration migration cycle, leaving northern latitudes during autumn. Here, we compared two species of diapausing Aglais butterflies, A. io and A. urtica, two species of the migratory genus Vanessa, V. atalanta and V. cardui, and two morphs of Polygonia c-album, the diapausing winter morph and the direct developing hutchinsoni morph. We tested how these different species differ in resource acquisition strategy during early adult life, how the acquisition of resources affects survival in cold winter conditions and how A. io, Aglais urticae and V. atalanta differ in resting metabolism under cold conditions. The butterflies set for adult diapause (1) acquired more mass during early adult life and (2) lost less mass and had a lower resting metabolism under cold conditions. In addition, (3) the life span under cold conditions was positively related to the weight increase during early adult life in the diapausing species, but not in the migratory species. Our laboratory results demonstrate how different developmental pathways, such as diapause or direct development, can be studied by measuring mass change in living butterflies. Our expectation that migratory species would increase in mass like species set for overwintering were not met, perhaps because such studies should ideally be performed under natural conditions. (c) 2023 The Author(s). Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour. This is an open access article under the CC BY license (http://creativecommons.org/licenses/ by/4.0/).
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| 48. |
- Friberg, Magne, et al.
(författare)
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Butterflies and plants : preference/performance studies in relation to plant size and the use of intact plants vs. cuttings
- 2016
-
Ingår i: Entomologia Experimentalis et Applicata. - : Wiley. - 0013-8703 .- 1570-7458. ; 160:3, s. 201-208
-
Tidskriftsartikel (refereegranskat)abstract
- Plants have evolved a number of defences to ameliorate herbivore attacks including chemicals induced by mechanical wounding. Such changes in plant chemical composition are potential confounding factors in experiments on plant-insect interactions, which often present cuttings of potential host plants to phytophagous insects. In particular, this could affect studies of female egg-laying preference and larval performance, because the same plant chemicals that deter certain generalist insects can elevate attacks from more specialized insects. Furthermore, plant cuttings are by definition smaller than intact plants, and any female host size preference could thus affect experiments using plant cuttings. We first assessed female preference and larval performance of a specialist herbivore, Pieris napi (L.) (Lepidoptera: Pieridae, Pierini), confronted with either intact plants or leaf-cuttings of four Brassicaceae host plants, Alliaria petiolata (Bieb.) Cavara & Grande, Barbarea vulgaris (L.) WT Aiton, Berteroa incana (L.) DC., and Brassica napus (L.). Egg and larval survival did not differ between intact plants and leaf-cuttings, whereas larval growth was slightly, but significantly, faster on leaf-cuttings. Females, however, significantly preferred to lay eggs on intact plants of all four hosts, although the preference hierarchy for the intact plants was largely mirrored by that for leaf-cuttings. We then tested the female preference for different size-classes of intact B. napus plants. Small individuals received more eggs than larger individuals, and follow-up experiments showed that this difference was largely generated by a strong female preference for cotyledon leaves; there was no significant difference in female preference for large and small individuals when both carried cotyledons, and females landing on cotyledons were more likely to oviposit compared to when landing on a true leaf. Our study concludes that plant cuttings can serve as adequate proxies for live plants for preference/performance studies, but that experimentalists should be aware of the variation imposed both by plant handling and plant phenology for female oviposition preference.
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| 49. |
- Friberg, Magne, et al.
(författare)
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Decoupling of female host plant preference and offspring performance in relative specialist and generalist butterflies
- 2015
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 178:4, s. 1181-1192
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Tidskriftsartikel (refereegranskat)abstract
- The preference-performance hypothesis posits that the host plant range of plant-feeding insects is ultimately limited by larval costs associated with feeding on multiple resources, and that female egg-laying preferences evolve in response to these costs. The trade-off of either using few host plant species and being a strong competitor on them due to effective utilization or using a wide host plant range but being a poor competitor is further predicted to result in host plant specialization. This follows under the hypothesis that both females and offspring are ultimately favoured by utilizing only the most suitable host(s). We develop an experimental approach to identify such trade-offs, i.e. larval costs associated with being a host generalist, and apply a suite of experiments to two sympatric and syntopic populations of the closely related butterflies Pieris napi and Pieris rapae. These butterflies show variation in their level of host specialization, which allowed comparisons between more and less specialized species and between families within species. Our results show that, first, the link between female host preference and offspring performance was not significantly stronger in the specialist compared to the generalist species. Second, the offspring of the host plant specialist did not outperform the offspring of the generalist on the former's most preferred host plant species. Finally, the more generalized species, or families within species, did not show higher survival or consistently higher growth rates than the specialists on the less preferred plants. Thus, the preference and performance traits appear to evolve as largely separated units.
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- Friberg, Magne, et al.
(författare)
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Female mate choice determines reproductive isolation between sympatric butterflies
- 2008
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Ingår i: Behavioral Ecology and Sociobiology. - Berlin : Springer Science and Business Media LLC. - 0340-5443 .- 1432-0762. ; 62:6, s. 873-886
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Tidskriftsartikel (refereegranskat)abstract
- Animal courtship rituals are important for species recognition, and a variety of cues might be utilized to recognize conspecific mates. In this paper, we investigate different species-recognition mechanisms between two sympatric butterfly sister species: the wood white (Leptidea sinapis) and Real's wood white (Leptidea reali). We show that males of both species frequently court heterospecific females both under laboratory and field conditions. The long-lasting elaborate courtships impose energetic costs, since the second courtship of males that were introduced to two subsequent conspecific females lasted on average only one fourth as long as the first courtship. In this paper, we demonstrate that premating reproductive isolation is dependent on female unwillingness to accept heterospecific mates. We studied female and male courtship behavior, chemical signaling, and the morphology of the sexually dimorphic antennae, one of the few male traits visible for females during courtship. We found no differences in ultraviolet (UV) reflectance and only small differences in longer wavelengths and brightness, significant between-species differences, but strongly overlapping distributions of male L. sinapis and L. reali antennal morphology and chemical signals and minor differences in courtship behavior. The lack of clear-cut between-species differences further explains the lack of male species recognition, and the overall similarity might have caused the long-lasting elaborate courtships, if females need prolonged male courtships to distinguish between con- and heterospecific suitors.
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