| 1. |
- Bengtsson, Jan
(author)
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Biological control as an ecosystem service: partitioning contributions of nature and human inputs to yield
- 2015
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In: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 40, s. 45-55
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Journal article (peer-reviewed)abstract
- 1. The concept of ecosystem services (ES) has rapidly entered policy and planning agendas nationally and globally. However, its usefulness is hampered by, for example, insufficient understanding of underlying ecological processes and poorly developed and competing conceptual frameworks. 2. It is suggested that final ecosystem services, such as yield, can be partitioned into components describing contributions from ecosystems (regulating and maintenance ES as natural inputs) and human inputs. This conceptual framework is tested by examining the relative importance of farming system (conventional vs. organic, indicating human inputs, and management), landscape (field shape and landscape heterogeneity), and biological control of aphids by natural enemies (indicating a regulating ES) for barley yield on 10 fields in central Sweden. 3. Although biological control was related to increased yield, its contribution was relatively small (<20%). The farming system explained most of the magnitude and variation in yield (47% of the variation, of which 34% was unique). Landscape and biological control had the largest shared contribution to variation in yield (14%). Conventional farming management seemed to have a larger effect on yield than biological control. This could be interpreted as indicating that agricultural production should be further intensified to increase yields, but a high dependency on external inputs may cause further environmental problems, such as eutrophication, and may not be sustainable. 4. Although preliminary, the results suggest that partitioning of natural and human inputs is useful to analyse the contribution of regulating ES to final ecosystem services, and how ES are co-produced by ecosystems and humans.
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| 2. |
- Ekholm, Adam, et al.
(author)
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The forgotten season : the impact of autumn phenology on a specialist insect herbivore community on oak
- 2019
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In: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 44:3, s. 425-435
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Journal article (peer-reviewed)abstract
- 1. Variation in spring phenology - like tree budburst - affects the structure of insect communities, but impacts of autumn phenology have been neglected. Many plant species have recently delayed their autumn phenology, and the timing of leaf senescence may be important for herbivorous insects.2. This study explored how an insect herbivore community associated with Quercus robur is influenced by variation in autumn phenology. For this, schools were asked to record, across the range of oak in Sweden, the autumn phenology of oaks and to conduct a survey of the insect community.3. To tease apart the relative impacts of climate from that of tree phenology, regional tree phenology was first modelled as a function of regional climate, and the tree-specific deviation from this relationship was then used as the metric of relative tree-specific phenology.4. At the regional scale, a warmer climate postponed oak leaf senescence. This was also reflected in the insect herbivore community: six out of 15 taxa occurred at a higher incidence and five out of 18 taxa were more abundant, in locations with a warmerclimate. Similarly, taxonomic richness and herbivory were higher in warmer locations.5. Trees with a relatively late autumn phenology had higher abundances of leaf miners (Phyllonorycter spp.). This caused lower community diversity and evenness on trees with later autumn phenology.6. The findings of the present study illustrate that both regional climate-driven patterns and local variation in oak autumn phenology contribute to shaping the insect herbivore community. Community patterns may thus shift with a changing climate.
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| 3. |
- Friberg, Magne, et al.
(author)
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Host preference variation cannot explain microhabitat differentiation among sympatric Pieris napi and Pieris rapae butterflies
- 2019
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In: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 44:4, s. 571-576
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Journal article (peer-reviewed)abstract
- 1. Often, closely related insect species feed on different host plant species, and the tremendous diversity of phytophagous insects is therefore attributed to host plant-driven speciation. However, for most taxa, host use information comes from field observations of egg-laying females or feeding caterpillars, which means that the underlying reason for a particular host-affiliation is not easily determined. 2. Therefore, it is often unclear whether an insect feeds on a certain host because it prefers that plant to alternative hosts, or because the host distribution overlaps with the habitat requirements of the insect. 3. We ask to what extent a divergent host use in the field mirrors the host plant preferences of two closely related butterflies, Pieris napi and Pieris rapae (Pieridae). In nature, P. napi typically occurs in moister habitats than P. rapae. 4. We scanned several microhabitats at a field site in Southern Sweden during multiple years, and collected Pieris eggs from three different plants, Cardamine pratensis (wet meadows), Barbarea vulgaris (drier micro-habitats) and Alliaria petiolata (intermediate areas). 5. As predicted, P. rapae eggs were more common than P. napi eggs on B. vulgaris, whereas all of the 358 individuals collected from C. pratensis were P. napi, indicating a divergence in host use between the Pieris species. However, under controlled laboratory conditions, both species had virtually identical oviposition preferences, laying eggs on all three plants, notably P. rapae also laying eggs on C. pratensis, indicating that habitat use, not plant preference, drives host plant use in nature.
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| 4. |
- Golab, Maria J., et al.
(author)
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Let's mate here and now - seasonal constraints increase mating efficiency
- 2019
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In: Ecological Entomology. - : WILEY. - 0307-6946 .- 1365-2311. ; 44:5, s. 623-629
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Journal article (peer-reviewed)abstract
- 1. Latitudinal climatic conditions shape the length of the mating season and could thus influence reproductive traits. Knowledge of how animals behave along latitudinal clines will increase understanding of the impact of climate on sexual selection and might help in the prediction of whether peripheral populations will spread or shrink in response to changes in climate. 2. This study investigated variation in the mating efficiency of a temperate insect, the emerald damselfly Lestes sponsa, under semi-natural field conditions along a latitudinal gradient covering three regions of the species' distribution: south, central and north. 3. A comparison was done of the proportion of copulating males, the proportion of males that formed tandems but did not copulate (unsuccessful males), and the proportion of males that did not attempt to form a tandem (passive males) in these three regions. 4. It was found that the proportion of copulations was significantly higher at northern latitudes than in the southern and central regions. Southern latitudes had a higher proportion of successful copulations compared with central latitudes. The northern region had a significantly lower frequency of passive males. The southern region had an intermediate proportion of passive males, and the central region had the highest proportion. The proportion of unsuccessful males did not differ between regions. The population density across sites did not affect these results. 5. The study shows that damselflies inhabiting northern populations mate more intensively than individuals from southern and central populations. This suggests that more restrictive environmental conditions during a brief mating season select for higher mating efficiency.
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| 5. |
- Jander, K. Charlotte
(author)
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Indirect mutualism : ants protect fig seeds and pollen dispersers from parasites
- 2015
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In: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 40:5, s. 500-510
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Journal article (peer-reviewed)abstract
- 1. Mutualisms are ubiquitous and ecologically important, but may be particularly vulnerable to exploitation by species outside of the mutualism owing to a combination of an attractive reward and potentially limited defence options. For some mutualisms, ants can offer dynamic and relatively selective protection against herbivores and parasites. 2. The mutualism between fig trees and their pollinating wasps, a keystone mutualism in tropical forests, is particularly well suited for ant protection because pollinators are protected inside hollow inflorescences but parasites are exposed on the outside. 3. In the present study, it was shown that the presence of ants provides a fitness benefit for both the pollinators and the hosting fig tree. The presence of ants (i) reduced abortions of developing figs, (ii) reduced herbivory of figs, and (iii) reduced parasitic wasp loads, resulting in more pollinators and more seeds in ant-protected figs. Even when taking costs such as ant predation on emerging pollinators into account, the total fitness increase of hosting ants was threefold for the tree and fivefold for the pollinators. 4. It was further shown that the seemingly most vulnerable parasitic wasps, of the genus Idarnes, have a specific behaviour that allows them to evade ant attack while continuing to oviposit. 5. Ants were present on 79% of surveyed Panamanian fig trees. Together with previous studies from the Old World, the results found here imply that ants are both powerful and common protectors of the fig mutualism worldwide.
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| 6. |
- Mair, Louise
(author)
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Quantifying the activity levels and behavioural responses of butterfly species to habitat boundaries
- 2015
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In: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 40, s. 823-828
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Journal article (peer-reviewed)abstract
- 1. The ability of species' to undergo climate-driven range shifts across fragmented landscapes depends on their dispersal ability as well as the structure of the landscape. For species' range shifts to occur, individuals must first leave suitable habitat to seek new habitat; this is likely to depend on the rate of movement of individuals within habitat and the likelihood that a boundary is crossed, once it is encountered. For three species of butterfly with contrasting histories of recent range expansion, we examined the propensity of individuals to move within a habitat and their responses to habitat boundaries. 2. We quantified the extent to which Plebejus argus (Linnaeus) (a declining habitat specialist), Aricia agestis (Schiffermuller) (an expanding generalist) and Polymmatus icarus (Rottemburg) (a geographically ubiquitous generalist) crossed habitat boundaries into unsuitable habitat and moved within suitable habitat. The observed movement was then related to individual and environmental conditions. 3. Species differed in their activity levels in accordance within their recent distribution patterns (P. icarus > A. agestis > P. argus). Our results for P. argus suggest that movement may be motivated by nectar-seeking, and that males generally move more than females. All three species tended to avoid crossing habitat boundaries; however the proportion of individuals crossing habitat boundaries did not differ significantly among species. 4. We conclude that levels of activity within a habitat, which will affect the frequency with which individuals encounter habitat boundaries, rather than behavioural responses to the boundaries, may be important drivers of distribution change.
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| 7. |
- Metcalfe, Daniel B., et al.
(author)
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Ecological stoichiometry and nutrient partitioning in two insect herbivores responsible for large-scale forest disturbance in the Fennoscandian subarctic
- 2019
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In: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 44:1, s. 118-128
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Journal article (peer-reviewed)abstract
- 1. Outbreaks of herbivorous insects can have large impacts on regional soil carbon (C) storage and nutrient cycling. In northernmost Europe, population outbreaks of several geometrid moth species regularly cause large-scale defoliation in subarctic birch forests. An improved understanding is required of how leaf C and nutrients are processed after ingestion by herbivores and what this means for the quantity and quality of different materials produced (frass, bodies). 2. In this study, larvae of two geometrid species responsible for major outbreaks (Epirrita autumnata and Operophtera brumata) were raised on exclusive diets of Betula pubescens var. czerepanovii (N. I. Orlova) Hämet Ahti and two other abundant understorey species (Betula nana, Vaccinium myrtillus). The quantities of C, nitrogen (N) and phosphorus (P) ingested and allocated to frass, bodies and (in the case of C) respired were recorded. 3. Overall, 23%, 70% and 48% of ingested C, N and P were allocated to bodies, respectively, rather than frass and (in the case of C) respiration. Operophtera brumata consistently maintained more constant body stoichiometric ratios of C, N and P than did E. autumnata, across the wide variation in physico-chemical properties of plant diet supplied. 4. These observed differences and similarities on C and nutrient processing may improve researchers' ability to predict the amount and stoichiometry of frass and bodies generated after geometrid outbreaks.
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| 8. |
- Nylin, Sören, et al.
(author)
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Vestiges of an ancestral host plant: preference and performance in the butterfly Polygonia faunus and its sister species P. c-album
- 2015
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In: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 40:3, s. 307-315
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Journal article (peer-reviewed)abstract
- 1. In the study of the evolution of insect-host plant interactions, important information is provided by host ranking correspondences among female preference, offspring preference, and offspring performance. Here, we contrast such patterns in two polyphagous sister species in the butterfly family Nymphalidae, the Nearctic Polygonia faunus, and the Palearctic P. c-album. 2. These two species have similar host ranges, but according to the literature P. faunus does not use the ancestral host plant clade-the urticalean rosids'. Comparisons of the species can thus test the effects of a change in insect-plant associations over a long time scale. Cage experiments confirmed that P. faunus females avoid laying eggs on Urtica dioica (the preferred host of P. c-album), instead preferring Salix, Betula, and Ribes.3. However, newly hatched larvae of both species readily accept and grow well on U. dioica, supporting the general theory that evolutionary changes in host range are initiated through shifts in female host preferences, whereas larvae are more conservative and also can retain the capacity to perform well on ancestral hosts over long time spans.4. Similar rankings of host plants among female preference, offspring preference, and offspring performance were observed in P. c-album but not in P. faunus. This is probably a result of vestiges of larval adaptations to the lost ancestral host taxon in the latter species. 5. Female and larval preferences seem to be largely free to evolve independently, and consequently larval preferences warrant more attention.
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| 9. |
- Rasmussen, Pil U., et al.
(author)
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Plant and insect genetic variation mediate the impact of arbuscular mycorrhizal fungi on a natural plant-herbivore interaction
- 2017
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In: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 42:6, s. 793-802
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Journal article (peer-reviewed)abstract
- 1. While both arbuscular mycorrhizal (AM) fungi and plant and insect genotype are well known to influence plant and herbivore growth and performance, information is lacking on how these factors jointly influence the relationship between plants and their natural herbivores. 2. The aim of the present study was to investigate how a natural community of arbuscular mycorrhizal fungi affects the growth of the perennial herb Plantago lanceolata L. (Plantaginaceae), as well as its interaction with the Glanville fritillary butterfly [Melitaea cinxia L. (Nymphalidae)]. For this, a multifactorial experiment was conducted using plant lines originating from multiple plant populations in the angstrom land Islands, Finland, grown either with or without mycorrhizal fungi. For a subset of plant lines, the impact of mycorrhizal inoculation, plant line, and larval family on the performance of M. cinxia larvae were tested. 3. Arbuscular mycorrhizal inoculation did not have a consistently positive or negative impact on plant growth or herbivore performance. Instead, plant genetic variation mediated the impact of arbuscular mycorrhizal fungi on plant growth, and both plant genetic variation and herbivore genetic variation mediated the response of the herbivore. For both the plant and insect, the impact of the arbuscular mycorrhizal community ranged from mutualistic to antagonistic. Overall, the present findings illustrate that genetic variation in response to mycorrhizal fungi may play a key role in the ecology and evolution of plant-insect interactions.
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| 10. |
- Roslin, Tomas
(author)
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A stable, genetically determined colour dimorphism in the dung beetle Aphodius depressus: patterns and mechanisms
- 2015
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In: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 40, s. 575-584
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Journal article (peer-reviewed)abstract
- 1. Melanism - the occurrence of dark morphs - in insects has been attributed to differences in, among other things, thermoregulation and immune defence. Dark individuals are hypothesised to perform better in colder areas, and to exhibit stronger melanin-based immune defence. 2. In the present study, the geographical distribution of two colour morphs in Aphodius depressus (Kugelann), its climatic correlates, and temporal stability was described. Underlying mechanisms were then targeted through experiments: the inheritance of colour through controlled crosses, heating rates by thermal imaging, physiological tolerance by critical thermal limits, and immune efficiency by melanisation of implants. 3. In A. depressus, colour appears inherited by simple Mendelian principles, with red dominating over black. The frequency of two colour morphs forms a large-scale cline. In the South West of Finland, all individuals are black, whereas, in the North East, most are red. This pattern has remained constant over 13 years (1996-2008). 4. The geographical pattern was not attributable to thermoregulation: black morphs were more abundant in warmer rather than colder parts of the country. In experiments, we found no differences in the heating rate of the two morphs, or in their upper temperature maxima. Neither did the morphs differ in their response to artificial objects inserted in their haemolymph. 5. Overall, colour variation in A. depressus occurs as a stable, genetically determined dimorphism, governed by Mendelian inheritance. Yet, no support for prevailing theory of factors sustaining melanism was found. The reasons for colour polymorphism in insects may thus be complex, and should be sought on a case-by-case basis.
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| 11. |
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| 12. |
- Sniegula, Szymon, et al.
(author)
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A large-scale latitudinal pattern of life-history traits in a strictly univoltine damselfly
- 2016
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In: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 41:4, s. 459-472
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Journal article (peer-reviewed)abstract
- 1. Variation in thermal conditions and season length along latitudinal gradients affect body size-related traits over different life stages. Selection is expected to optimise these size traits in response to the costs and benefits. 2. Egg, hatchling, larval and adult size in males and females were estimated along a latitudinal gradient of 2730km across Europe in the univoltine damselfly Lestes sponsa, using a combination of field-collection and laboratory-rearing experiments. In the laboratory, individuals were grown in temperatures and photoperiod simulating those at the latitude of origin, and in common-garden conditions. 3. The size of adults sampled in nature was negatively correlated with latitude. In all populations the females were larger than the males. Results from simulated and common-garden rearing experiments supported this pattern of size difference across latitudes and between sexes, suggesting a genetic component for the latitudinal size trend and female-biased size dimorphism. In contrast, hatchling size showed a positive relationship with latitude, but egg size, although differing between latitudes, showed no such relationship. 4. The results support a converse Bergmann cline, i.e. a negative body size cline towards the north. This negative cline in body size is probably driven by progressively stronger seasonal time and temperature constraints towards the higher latitudes and by the obligate univoltine life cycle of L. sponsa. As egg size showed no relationship with latitude, other environmental factors besides temperature, such as desiccation risk, probably affect this trait.
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| 13. |
- Sniegula, Szymon, et al.
(author)
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Do males with higher mating success invest more in armaments? : An across-populations study in damselflies
- 2017
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In: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 42:4, s. 526-530
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Journal article (peer-reviewed)abstract
- 1. Males with higher mating success would be expected to invest more in traits that facilitate mating, leading to steeper allometry of those traits with respect to body size. Across-population studies following latitudinal variation in male mating success are an excellent study system to address this question.2. Males of the damselfly Lestes sponsa were used to investigate whether the allometric patterns of the length and width of the anal appendages, used for grasping the female prior tomating, corresponded to male mating success. Across a large latitudinal gradient, it was hypothesised that there is a larger investment in the grasping apparatus, i.e. a steeper allometric slope, following higher mating success.3. Behavioural observations in field enclosures showed the highest mating success at high latitude, while there were no significant differences in mating success between the central and low latitudes. Positive allometry was found for the length of the anal appendages in high-latitude males, while central-and low-latitude males showed no significant regressions of the traits on body size.4. These results partially support the hypothesis, as high-latitude, more successful males invested more in the length ( but not the width) of the grasping apparatus than did central-and low-latitude males. Therefore, higher mating success might be facilitated by larger investment in armaments. Intraspecific studies on allometric patterns of traits that participate in mating success might offer new insights into the role of those traits in the reproductive behaviour of a species.
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| 14. |
- St-Martin, Audrey
(author)
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Genetic signature of the colonisation dynamics along a coastal expansion front in the damselfly Coenagrion scitulum
- 2015
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In: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 40, s. 353-361
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Journal article (peer-reviewed)abstract
- 1. Many insects are expanding their distribution range polewards as a result of climate change, which has been shown to be associated with founder effects leading to a reduction in genetic diversity and an increase in genetic differentiation. These spatial genetic patterns may arise from colonisation from a broad expansion front or a limited neighbourhood after a stepping stone model of dispersal. The temporal persistence of such founder effects are poorly understood, mainly because studies looking at the fine-scale initial temporal dynamics of the genetic signature of a range expansion are rare. 2. Using microsatellite markers, we performed a detailed spatiotemporal genetic analysis of the range expanding damselfly Coenagrion scitulum (Rambur) along a coastal axis during the first years after colonisation. 3. A decrease was in (private) allelic richness when going northwards along the coastline, which is consistent with a scenario of cumulative founder events. In spite of the spatiotemporal dynamics in the observation records of the species along the coastline, the spatial genetic data indicated a major contribution from the broad expansion front during the colonisation of the coastline rather than a stepping-stone colonisation process. 4. The fine-scale temporal dynamics of the range expansion indicated the absence of persistent founder effects and instead showed considerable temporal instability in genetic indices at the more northern edge populations. This may be explained by genetic immigration and admixture from the broad expansion front in this active disperser.
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| 15. |
- Wiklund, Christer, et al.
(author)
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Host plant exodus and larval wandering behaviour in a butterfly : diapause generation larvae wander for longer periods than do non-diapause generation larvae
- 2017
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In: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 42:4, s. 531-534
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Journal article (peer-reviewed)abstract
- 1. Prior to pupation, lepidopteran larvae enter a wandering phase lasting up to 30 h before choosing a pupation site. Because stillness is important for concealment, this behaviour calls for an adaptive explanation.2. The explanation most likely relates to the need to find a suitable pupation substrate, especially in terms of shelter from predation, and given that many predators and parasitoids use host plants as prey-location cues, mortality probably decreases with distance from the host plant. Hence, remaining on the host includes a long-term risk, while moving away from the host introduces an increased risk during locomotion.3. Bivoltine species that overwinter in the pupal stage produce two kinds of pupae; non-diapausing pupae from which adults emerge after 1-2 weeks, or diapausing pupae that overwinter with adults emerging after 8-10 months.4. Given the hypothesis of distance-from-host-plant-related predation, this should select for phenotypic plasticity with larvae in the diapausing generation having a longer wandering phase than larvae under direct development, if there is a trade-off between mortality during the wandering phase and accumulated mortality during winter.5. Here this prediction is tested by studying the duration of the wandering period in larvae of the partially bivoltine swallowtail butterfly, Papilio machaon, under both developmental pathways.6. The results are in agreement with the predictions and show that the larval wandering phase is approximately twice as long under diapause development. The authors suggest that the longer duration of the wandering phase in the diapause generation is a general phenomenon in Lepidoptera.
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| 16. |
- Zmihorski, Michal
(author)
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The importance of diurnal and nocturnal activity and interspecific interactions for space use by ants in clear-cuts
- 2016
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In: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 41, s. 276-283
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Journal article (peer-reviewed)abstract
- I. Full sunlight conditions in open clear-cuts may limit he activity of ants as soil surface temperatures reach lethal levels. Therefore, differences may be expected between the diurnal and nocturnal activity of ants, and in the interactions between ant species. These predictions, however, have been poorly investigated so far.2. The circadian activity of ants in clear-cuts in managed forests in Poland was investigated. Repeated counts of ants were performed during the day and the following night at the clear-cut edge and in the clear-cut interior. Interspecific interactions and the effect of plant coverage were also considered.3. Abundances of Formica fusca Linnaeus and red wood ants were higher during the day, whereas Myrmica were more common at night. Formica fusca, Lasius and red wood ants were more common at the clear-cut edge than in the interior. Mvrtnica showed the opposite pattern, but at night, its numbers increased at the edge. Plant coverage positively affected F.fusca and red wood ants.4. Red wood ants tended to be negatively associated with Lasius, whereas they were neutral for Efusca. The negative association of red wood ants and was stronger during the day compared to night.5. The time of day was a strong driver of ant activity in the clear-cuts, whereas the distribution of red wood ants was of lesser importance. It is concluded that circadian activity may substantially contribute to niche separation between coexisting species, therefore, studies performed exclusively during the day cannot reflect the real structure of the community.
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