| 1. |
- 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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| 2. |
- 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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| 3. |
- Bergman, Martin, et al.
(författare)
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Contest outcome in a territorial butterfly : the role of motivation
- 2010
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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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| 4. |
- Bergman, Martin, et al.
(författare)
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Mating success of resident versus non-resident males in a territorial butterfly
- 2007
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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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| 5. |
- Fogelström, Elsa, et al.
(författare)
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Plant-herbivore synchrony and selection on plant flowering phenology
- 2017
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Ingår i: Ecology. - : Wiley. - 0012-9658 .- 1939-9170. ; 98:3, s. 703-711
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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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| 6. |
- Friberg, Magne, et al.
(författare)
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Habitat choice precedes host plant choice - niche separation in a species pair of a generalist and a specialist butterfly
- 2008
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Ingår i: Oikos. - Lund : Department of Ecology, Lund university. ; 117:9, s. 1337-1344
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Tidskriftsartikel (refereegranskat)abstract
- The sister species Leptidea reali and L. sinapis have partitioned their niches differently in different parts of their sympatric distribution. In Spain and France L. sinapis is a widespread generalist whereas L. reali is specialized on high altitude open areas. Interestingly, the reverse is true in Ireland and the Czech Republic where L. reali is widespread and L. sinapis specialized on meadows. In Sweden, L. reali is a habitat specialist confined to meadows, whereas L. sinapis is a habitat generalist also inhabiting forests. Ultimately, the geographic mosaic of niche separation is the result of local processes in each contact zone or a secondary effect of the host plant distribution, if L. sinapis and L. reali prefer different legume host plants. Hence, in Sweden L. sinapis might utilize the forest habitat either due to a wider habitat preference or due to a wider host plant preference than L. reali. Studies of wild butterflies showed that L. sinapis laid 26% of their eggs on forest-associated legumes compared to 6% in L. reali, although laboratory experiments showed that both species had virtually identical host plant preferences strongly preferring the meadow-associated legume Lathyrus pratensis. Furthermore, flight duration tests in a variety of temperatures demonstrated a between-species difference; L. sinapis females reached their flight optimum at a lower temperature than L. reali females. The lower L. sinapis flight temperature optimum is most probably a secondary effect due to habitat-specific selection, and therefore a consequence rather than the cause of the habitat partitioning. The finding that habitat choice precedes host plant choice suggests that the European geographic mosaic of niche separation, with L. sinapis and L. reali shifting habitat specialist/generalist roles, is not caused by rigid between-species differences in a related niche parameter, but instead is a result of local processes within each secondary contact zone.
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| 7. |
- Lukhtanov, Vladimir A., et al.
(författare)
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Versatility of multivalent orientation, inverted meiosis, and rescued fitness in holocentric chromosomal hybrids
- 2018
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 115:41, s. E9610-E9619
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Tidskriftsartikel (refereegranskat)abstract
- Chromosomal rearrangements (e.g., fusions/fissions) have the potential to drive speciation. However, their accumulation in a population is generally viewed as unlikely, because chromosomal heterozygosity should lead to meiotic problems and aneuploid gametes. Canonical meiosis involves segregation of homologous chromosomes in meiosis I and sister chromatid segregation during meiosis II. In organisms with holocentric chromosomes, which are characterized by kinetic activity distributed along almost the entire chromosome length, this order may be inverted depending on their metaphase I orientation. Here we analyzed the evolutionary role of this intrinsic versatility of holocentric chromosomes, which is not available to monocentric ones, by studying F-1 to F-4 hybrids between two chromosomal races of the Wood White butterfly (Leptidea sinapis), separated by at least 24 chromosomal fusions/fissions. We found that these chromosomal rearrangements resulted in multiple meiotic multivalents, and, contrary to the theoretical prediction, the hybrids displayed relatively high reproductive fitness (42% of that of the control lines) and regular behavior of meiotic chromosomes. In the hybrids, we also discovered inverted meiosis, in which the first and critical stage of chromosome number reduction was replaced by the less risky stage of sister chromatid separation. We hypothesize that the ability to invert the order of the main meiotic events facilitates proper chromosome segregation and hence rescues fertility and viability in chromosomal hybrids, potentially promoting dynamic karyotype evolution and chromosomal speciation.
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| 8. |
- Olofsson, Martin, 1980-
(författare)
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Antipredator defence in butterflies
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Predation exerts a potent selection mechanism and has resulted in a suite of antipredation adaptations encompassing morphological and behavioral traits in prey. In butterflies, several such traits appear to be directed towards birds which are considered as one of their major predators. In this thesis I have investigated tactics by which adult butterflies may survive close encounters with birds. In paper I, I provide supporting evidence that the small white “comma” on females of the comma butterfly, Polygonia c-album, has a distractive function on blue tits and so reduces the attack risk. In paper II & III, I investigate the antipredator efficiency of sudden wing-flicking in two species, the peacock butterfly, Inachis io, and the European swallowtail, Papilio machaon, when confronted with domestic fowl and great tits, respectively. Peacock butterflies were manipulated to either display visible or painted over eyespots. Interestingly, the birds that confronted peacocks with visible eyespots were more likely to utter antipredator alarm calls, which imply that the eyespots may be perceived as real eyes of a potential predator. On the whole, wing-flicking in both species typically induced evasion in the birds which suggests that the birds became frightened rather than perceiving the butterflies as not profitable to attack for some other reason. Moreover, I use blue tits as predators to investigate the possible function of smaller eyespots of satyrine butterflies in that they serve to divert predator attacks. Evidence suggests that low light conditions accentuated in the UV may enhance the deflective function of marginal eyespots in the woodland brown butterfly, Lopinga achine (paper IV). In paper V, I show that the presence of one marginal eyespot on the speckled wood butterfly, Pararge aegeria, can deflect bird attacks; moreover, when the butterfly is concealed against the background, eyespots can also increase the latency time until bird attack. In conclusion, my thesis underscores that behavioral studies of predators are instrumental to aid our understanding of the adaptive significance of certain behavioral and morphological traits in prey.
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| 9. |
- Olofsson, Martin, et al.
(författare)
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Auditory defence in the peacock butterfly (Inachis io) against mice (Apodemus flavicollis and A. sylvaticus)
- 2012
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Ingår i: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 0340-5443 .- 1432-0762. ; 66:2, s. 209-215
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Tidskriftsartikel (refereegranskat)abstract
- Morphological and behavioural traits can serve as anti-predator defence either by reducing detection or recognition risks, or by thwarting initiated attacks. The latter defence is secondary and often involves a 'startle display' comprising a sudden release of signals targeting more than one sensory modality. A suggested candidate for employing a multimodal defence is the peacock butterfly, Inachis io, which, by wing-flicking suddenly, produces sonic and ultrasonic sounds and displays four large eyespots when attacked. The eyespots make small birds retreat, but whether the sounds produced thwart predator attacks is largely unknown. Peacocks hibernate as adults in dark wintering sites and employ their secondary defence upon encounter with small rodent predators during this period. In this study, we staged predator-prey encounters in complete darkness in the laboratory between wild mice, Apodemus flavicollis and Apodemus sylvaticus, and peacocks which had their sound production intact or disabled. Results show that mice were more likely to flee from sound-producing butterflies than from butterflies which had their sound production disabled. Our study presents experimental evidence that the peacock butterfly truly employs a multimodal defence with different traits targeting different predator groups; the eyespots target birds and the sound production targets small rodent predators.
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| 10. |
- Olofsson, Martin, 1980-, et al.
(författare)
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Bird attacks on a butterfly with marginal eyespots and the role of prey concealment against the background : Marginal eyespots can deflect bird attacks
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Small eyespots on butterflies have long been thought to deflect attacks and birds are presumptive drivers selecting for these patterns. However, evidence of this function is still ambiguous. Marginal eyespots typically consist of a UV-reflective white pupil, surrounded by one black and one yellowish ring. We have recently shown that blue tits attack such eyespots, but only under low light intensities with accentuated UV-levels. An increased salience of the eyespots relative to the rest of the butterfly probably explains this result. Possibly, a background against which the butterfly is concealed may deceive birds to making similar errors. We therefore presented speckled wood butterflies provided with eyespots (or controls without eyespots) to blue tits against two backgrounds, oak- and birch bark. Results show that (i) eyespots, independent of background, were effective in deflecting attacks, (ii) the time elapsed between a bird’s landing and attack was interactively dependent on background and whether the butterfly bore an eyespot and (iii) the speed at which a butterfly was attacked predicted the outcome, with faster birds being more prone to errors than slower birds. This underscores a speed-accuracy tradeoff in the predators and that background plays a role in the defensive qualities of marginal eyespots.
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