| 1. |
- Braga, Mariana P., et al.
(författare)
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Host repertoires and changing insect-plant interactions
- 2021
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Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 46:6, s. 1241-1253
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Forskningsöversikt (refereegranskat)abstract
- 1. One of the main challenges faced by ecologists today is to understand and predict how species interactions will respond to the current environmental change. It is likely that these changes will have a stronger effect on phylogenetic lineages that depend on intimate and specialised ecological interactions, such as most herbivorous insects.2. In this review, we highlight the aspects that we consider are fundamental for understanding how species interactions change over time. We start by reviewing terminology and conclude that commonly used terms have undesired connotations with regard to what we know about how hosts are acquired and lost over time.3. Based on that, we suggest host repertoire as a better term to describe the use of multiple hosts than the host range or diet breadth, both of which fail to capture that host use is often non-contiguous and tend to emphasise the total number of hosts, while ignoring host identity.4. Another important issue that we highlight is the differentiation between fundamental and realised host repertoires, where the latter is the set of hosts that are actually used in nature, whereas the first includes all hosts that can potentially be used by the species. We show that the characterisation of the fundamental host repertoire is key to understanding how insect-plant interactions will respond to the ecological opportunities instigated by environmental change.
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| 2. |
- Cuff, Jordan P., et al.
(författare)
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Sources of prey availability data alter interpretation of outputs from prey choice null networks
- 2024
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Ingår i: Ecological Entomology. - 0307-6946 .- 1365-2311.
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Tidskriftsartikel (refereegranskat)abstract
- Null models provide a valuable baseline against which fundamental ecological hypotheses can be tested and foraging choices that cannot be explained by neutral processes or sampling biases can be highlighted. In this way, null models can advance our understanding beyond simplistic dietary descriptions to identify drivers of interactions. This method, however, requires estimates of resource availability, which are generally imperfect representations of highly dynamic systems. Optimising method selection is crucial for study design, but the precise effects of different resource availability data on the efficacy of null models are poorly understood.Using spider–prey networks as a model, we used prey abundance (suction sample) and activity density (sticky trap) data, and combinations of the two, to simulate null networks. We compared null diet composition, network properties (e.g., connectance and nestedness) and deviations of simulations from metabarcoding-based spider dietary data to ascertain how different prey availability data alter ecological interpretation.Different sampling methods produced different null networks and inferred distinct prey selectivity. Null models based on prey abundance and combined frequency-of-occurrence data generated null diet compositions, which more closely resembled the diet composition determined by metabarcoding. Null models based on prey abundance, activity density and proportionally combined data generated null network properties most like the networks constructed via dietary metabarcoding.We show that survey method choice impacts all aspects of null network analyses, the precise effects varying between methods but ultimately altering ecological interpretation by increasing disparity in network properties or trophic niches between null and directly constructed networks. Merging datasets can generate more complete prey availability data but is not a panacea because it introduces different biases. The choice of method should reflect the research hypotheses and study system being investigated. Ultimately, survey methods should emulate the foraging mode of the focal predator as closely as possible, informed by the known ecology, natural history and behaviour of the predator.
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| 3. |
- Emery, Sara
(författare)
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Effects of predation pressure and prey density on short-term indirect interactions between two prey species that share a common predator
- 2020
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Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 45, s. 821-830
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Tidskriftsartikel (refereegranskat)abstract
- 1. Generalist predators are important contributors to reliable conservation biological control. Indirect interactions between prey species that share a common generalist predator can influence both community dynamics and the efficacy of biological control.2. Laboratory cage experiments investigated the impact of the combined consumptive and non-consumptive effects of predation by adult Hippodamia convergens as a shared predator on the population growth and relative abundance of Acyrthosiphon pisum and Aphis gossypii as prey species. Predation pressure and prey density were varied.3. At low predation pressure the indirect interaction between aphid species was asymmetrical with a proportionally greater negative impact of predation on A. gossypii than on A. pisum. At intermediate predation pressure, the indirect interaction became symmetrical. At high predation pressure and higher levels of prey density, it was asymmetrical with greater negative impact on A. pisum, often driven to local extinction while A. gossypii populations persisted.4. A linear mixed-effects model including early population growth of both aphid species and predation pressure explained 96% and 92% of the variation in the population growth of A. pisum and A. gossypii, respectively, over an 8-day period. The overall effect of shared predation on the indirect interaction between the two aphid species is best described as apparent commensalism, where A. pisum benefited from early population growth of A. gossypii, while A. gossypii was unaffected by early population growth of A. pisum. Considering these indirect interactions is important for conservation biological control efforts to be successful.
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| 4. |
- Everling, Sanne, et al.
(författare)
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The effect of temperature and behaviour on the interaction between two dragonfly larvae species within the native and expanded range
- 2022
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Ingår i: Ecological Entomology. - : John Wiley & Sons. - 0307-6946 .- 1365-2311. ; 47:3, s. 460-474
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Tidskriftsartikel (refereegranskat)abstract
- Studies on interaction between species are needed to observe and predict the effects of climate change on species distributions. Here we studied intra- and interspecific competition and behaviour in larvae of a native and a northward expanding dragonfly species, Sympetrum vulgatum and Sympetrum fonscolombii, respectively. We estimated growth, mortality, and behaviour (prey capture success, activity, and boldness) at 20 degrees C and 23 degrees C. The northward expanding S. fonscolombii had a higher growth rate and a higher survival compared with the native S. vulgatum in interspecific competition. In intraspecific conditions, there was no significant difference between species in mortality and growth. Temperature had no significant effect on growth and survival of S. fonscolombii, but S. vulgatum showed both a higher growth rate and a higher mortality at 23 degrees C under intraspecific conditions. There was a correlation between growth and mortality, suggesting that cannibalism and intraguild predation caused the growth differences between treatments in the competition experiments. Temperature had no significant effect on any of the behaviours. There were very few significant correlations between any of the behaviours and the life-history traits survival and growth and there were also very few significant correlations between any of the behaviours. Repeatability of behaviours over ontogeny was low. The results of the present study suggest that the range expanding S. fonscolombii has the potential to outcompete the native species, but that this competition advantage does not seem to be driven by the temperature effects explored in this study.
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| 5. |
- Gaytán, Álvaro, et al.
(författare)
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Strong impact of temperature and resource specialisation on patterns of voltinism within an oak‐associated insect community
- 2022
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Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 47:4, s. 544-552
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Tidskriftsartikel (refereegranskat)abstract
- 1. Insect phenology consists of the timing of life events, as well as the number of generations (voltinism). While several studies have focused on the impact of climate on the timing of seasonal events, or the voltinism of single species, we have few insights into the factors that shape patterns of voltinism within ecological communities. Importantly, voltinism can have a major impact on population growth, species interactions, and rate of evolution.2. We investigated the relative importance of spatial variation in temperature and species traits in shaping patterns of voltinism within an herbivore community feeding on deciduous oaks across a temperature gradient in Europe.3. Voltinism increased with temperature, where the probability for a species to be univoltine decreased with temperature, whereas the probability for a species to be strictly multivoltine increased with temperature. The relative abundance of the first and subsequent generations of multivoltine species did not significantly change along the temperature gradient. Resource specialisation affected voltinism, where oligophagous and polyphagous species were more likely to be strictly multivoltine than narrow oligophagous species. Overwintering stage and body size did not affect voltinism, and there was no evidence that species traits influenced the relationship between temperature and voltinism.4. Our findings highlight that temperature and species traits shape variation in voltinism within an herbivore community associated with oak trees. These temperature-induced shifts in voltinism within the oak-associated herbivore community may have profound effects on the synchrony within and between trophic levels, and consequently for food web structure and outbreak dynamics.
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| 6. |
- Larsson, Stig
(författare)
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Aggregative oviposition varies with density in processionary moths-Implications for insect outbreak propensity
- 2023
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Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 48, s. 102-111
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Tidskriftsartikel (refereegranskat)abstract
- In gregarious insects, groups commonly originate from females laying eggs in masses and feeding groups are established as soon as larvae hatch. Some group-living insect species may aggregate beyond the individual parent level, such that offspring from two or more egg masses develop within a common resource. Here we show that aggregative oviposition can vary with population density at oviposition and possibly be an important factor in outbreak dynamics of phytophagous insects. We analysed density data with respect to egg mass aggregation for two species of pine processionary moths, Thaumetopoea pinivora (in Sweden 2005-2019) and T. pityocampa (in Spain 1973-1991). Both species lay their eggs in egg masses and feed in groups. During the study periods, insect population density for both species varied by at least an order of magnitude. The two species showed strikingly similar patterns of egg mass aggregation. Egg masses were overdispersed at high population density, with few trees showing a high load of egg masses. Our data suggest that aggregative oviposition can be important in explaining the previously documented higher propensity for outbreaks in insects laying eggs in clusters, compared with those laying individual eggs.
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| 7. |
- Lindman, Ly, et al.
(författare)
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Microclimate in hollow trees and how it affects an inhabiting beetle species, Osmoderma eremita
- 2023
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Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 48, s. 112-126
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Tidskriftsartikel (refereegranskat)abstract
- Studies of species' responses to microclimatic conditions have increased our understanding of their habitat requirements and possible responses to climate warming. However, little is known about the role of microclimate for insects inhabiting hollow trees. We explored the relationship between tree characteristics and microclimate, and analysed how the microclimate in tree-hollows affects the occurrence and body size of an endangered beetle species, Osmoderma eremita. We placed temperature data-loggers in wood mould (= loose material in tree-hollows) and surveyed O. eremita in 47 hollows in oak pastures in south-eastern Sweden. We found that tree characteristics previously known to be associated with occurrence of beetle species confined to tree-hollows (larger diameters, more wood mould, entrances higher up, and not directed upwards) tend to decrease moisture and moisture variation, while their effects on temperature and temperature fluctuations differ during different seasons. This indicates that microclimatic conditions are important for beetles in hollow trees, and many specialised species seem to avoid conditions that are too moist. O. eremita occurred more frequently in trees with a warmer and more stable microclimate, while adult body size decreased with a warmer microclimate. A positive effect of a warmer microclimate was expected, since the study was done near the northern margin of the species' range. O. eremita is confined to living in hollow trees, which may be due to the microclimate there being more stable in comparison to both the ambient climate and the microclimate in standing and downed dead wood.
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| 8. |
- Murray, Rosalind L., et al.
(författare)
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Exposure to potentially cannibalistic conspecifics induces an increased immune response
- 2020
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Ingår i: Ecological Entomology. - : Royal Entomological Society. - 0307-6946 .- 1365-2311. ; 45:2, s. 355-363
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Tidskriftsartikel (refereegranskat)abstract
- 1. Within-population infectious disease dynamics depend on multiple factors, including the ability of hosts to mount an effective immune response. These immune responses can be highly plastic, responding to pathogen risk, as well as the ecological context in which pathogens are encountered.2. High conspecific density can stimulate immune activity, and recent research suggests that predators can cause indirect protective effects in their prey through the induction of increased immune responses. Comparatively little work, however, has investigated whether exposure to potentially cannibalistic conspecifics, representing both increased density and predatory pressures, will have similar effects on immune expression.3. Using dragonfly larvae, the present study investigated whether exposure to potentially cannibalistic conspecifics altered the melanisation of simulated parasites.4. Increased levels of melanisation were found in larvae regardless of whether that conspecific had recently engaged in cannibalism or not. Melanisation also increased as conspecific density increased, even if the conspecifics present were small, and therefore unlikely to pose a cannibalism threat.5. The findings obtained in the present study indicate that conspecific presence is sufficient to affect immune responses in these insects even though they are relatively solitary compared with the phase-polyphenic taxa typically associated with density-dependent prophylaxis. Because melanisation is also important for wound healing, we suggest that the increased melanin response observed with increased conspecific density might act to induce heightened immunity when faced with potentially increased risk of infection, and also facilitate wound healing under threat of predation/cannibalism.
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| 9. |
- Norman, Hannah, et al.
(författare)
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Novel grid-based population estimates correlate with actual population sizes of the marsh fritillary (Euphydryas aurinia), while transect and larvae counts are less reliable
- 2024
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Ingår i: Ecological Entomology. - : John Wiley & Sons. - 0307-6946 .- 1365-2311. ; 49:2, s. 180-190
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Tidskriftsartikel (refereegranskat)abstract
- 1. Established butterfly survey methods that are useful for monitoring species that are widely distributed and numerous may be less accurate for more rare species. We therefore need new monitoring approaches.2. We describe a plot-based survey method, where butterflies or larvae nests are counted within 1-ha grid cells. The aim was to compare this grid method with more traditional transect counts and evaluate both methods in relation to high-quality capture-mark-release (CMR) population estimates (reflecting the 'true' population). We do this using data from a large population of the marsh fritillary butterfly in Sweden. Moreover, we followed the overall population trend from 2017 to 2021 for both adult butterflies and larvae.3. Results showed a higher detection probability using the grid method compared with transect counts, which for adult butterflies seem to be explained by time effort. Moreover, grid surveys of adult butterflies showed a clear significant relationship with the estimated 'true' population size from CMR, while transect counts did not. For larvae, both methods showed significant relationships with the estimated adult population size, but the grid method found 5.7 times more larvae. The overall popu-lation fluctuated significantly across years. In years with low densities, the transect method largely failed to detect the species.4. The grid method seems more reliable for detecting the marsh fritillary and for estimating its population size, and thus, tracking the population trend. We propose this novel method to be integrated into surveys and monitoring of biodiversity, especially when focusing on rare habitat specialists that are normally underrepre-sented in monitoring based on volunteer counts.
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| 10. |
- Polic, Daniela, et al.
(författare)
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Movements and occurrence in two closely related fritillary species
- 2021
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Ingår i: Ecological Entomology. - : John Wiley & Sons. - 0307-6946 .- 1365-2311. ; 46:2, s. 428-439
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Tidskriftsartikel (refereegranskat)abstract
- Mobility may affect species' distribution patterns in heterogeneous landscapes, and it might impact fitness by influencing mating success, predation avoidance, and foraging success. Here, we studied causes and consequences of mobility patterns in butterflies: Argynnis adippe, a specialist constrained to warm microhabitats within woodland landscapes, and A. aglaja, a relative generalist that also inhabits grasslands, and tolerates lower temperatures. We explored associations of movement and occurrence patterns, population size and density, niche breadth, wing size, and different types of behaviour prior to capture by conducting a mark-release-recapture study on the Swedish island oland. We marked 1 935 A. aglaja and 123 A. adippe and achieved recapture rates of 9.5% (A. aglaja), and 8.9% (A. adippe). Estimated population densities were 5 066 and 814 individuals per km(2), for A. aglaja and A. adippe, respectively. Argynnis aglaja was less likely to perform long-distance flights according to estimated dispersal kernels, hinting at negative density-dependent dispersal in these species. Although we detected the longest flight distances ever in these species in MRR studies (11.9 km for A. aglaja and 3.7 km for A. adippe), most butterflies were recaptured within 200 meters (60-80%). Low recapture rates along with low estimated residence times and the potential for long movement might indicate that many individuals left the study area, and that the species form open populations, stretching over large areas. Despite significant differences in wing size and behaviour types, mean observed flight distances were similar in these species.
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| 11. |
- Rappa, Nolan James
(författare)
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Forest structure and heterogeneity increase diversity and alter composition of host-parasitoid networks
- 2024
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Ingår i: Ecological Entomology. - 0307-6946 .- 1365-2311. ; 49, s. 257-271
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Tidskriftsartikel (refereegranskat)abstract
- Antagonistic host-parasitoid interactions can be quantified using bipartite and metanetworks, which have the potential to reveal how habitat structural elements relate to this important ecosystem function.Here, we analysed the host-parasitoid interactions of cavity-nesting bees and wasps, as well as their abundance, diversity and species richness with forest structural elements from 127 forest research plots in southwestern Germany.We found that parasitoid abundance, diversity and species richness all increase with host abundance, a potential mediator between parasitoids and forest structure. Both parasitoid abundance and diversity increased with stand structural complexity, possibly mediated by the abundance of hosts. In addition, parasitoid abundance increased with increasing standing deadwood and herb cover.The bipartite networks of host-parasitoid interactions showed higher connectance with increasing standing deadwood, herb cover and host abundance. Analyses of interactions within the host-parasitoid metanetwork revealed that increasing host abundance and decreasing canopy cover diversify the suites of interactions present at the plot level.These results demonstrate that forest structural elements can improve the stability and resilience of host-parasitoid networks by promoting parasitoids and diversifying interactions in ecological networks.Cavity-nesting bees and wasps and their associated parasitoids rely on forest structural elements such as deadwood. Host-parasitoid interaction networks can reveal how these forest structures can support this important ecosystem function.Here, we sample cavity-nesting bee wasps and their parasitoids from 127 forest research sites, along with gradients of amounts of forest structural elements.We found that increasing amounts of forest structural elements increased the diversity of parasitoids and altered species composition, partly via increasing host abundance. In addition, canopy openness diversified suites of host-parasitoid interactions.image
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| 12. |
- Wiklund, Christer, 1945-, et al.
(författare)
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Testing the migration syndrome : Comparative fecundity of migratory and non-migratory nymphaline butterflies
- 2022
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Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 47:6, s. 1061-1067
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Tidskriftsartikel (refereegranskat)abstract
- 1. Empirical studies have shown a positive relationship between migration and fecundity, suggesting a 'migration syndrome' that also includes delayed reproduction and an extended reproductive lifespan. At the same time, life history theory predicts that the cost of migration should result in lower fecundity because both traits draw from a common resource.2. We test whether migration is associated with higher fecundity and delayed reproduction in five closely related butterfly species in the Nymphalini tribe. Two of these are migratory, Vanessa cardui and Vanessa atalanta, and three are non-migratory, Aglais urticae, Aglais io, and Polygonia c-album, which appears in a diapausing and a non-diapausing generation.3. Laboratory experiment of this study demonstrated a higher lifetime fecundity in the non-migratory species A. urticae and A. io, compared with the migratory species. When reproductive output was measured in terms of egg mass over adult female mass, also the non-migratory species P. c-album had a higher reproductive investment than the two migratory species, and the non-diapausing generation had a higher reproductive output than the diapausing generation. All species but P. c-album delayed reproduction until 5-7 days after eclosion/emergence.4. These results indicate that a migratory lifestyle carries a reproductive cost and suggests that the migratory habit has not resulted in selection for higher fecundity. However, the migratory species are highly fecund in a wider phylogenetic perspective, which leads to the conclusion that rather than selection having selected for high fecundity and delayed reproduction, these traits may be prerequisites for evolving a migratory lifestyle.
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| 13. |
- Willink, Beatriz, et al.
(författare)
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Population biology and phenology of the colour polymorphic damselfly Ischnura elegans at its southern range limit in Cyprus
- 2021
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Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 46:3, s. 601-613
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Tidskriftsartikel (refereegranskat)abstract
- 1. Geographically widespread species provide excellent opportunities to investigate how phenotypes change across large-scale environmental gradients. Temperature is a fundamental environmental variable and an important determinant of insect fitness. However, field research is often geographically restricted, and typically concentrated in northern latitudes. Basic population biology and phenotypic clines in relation to temperature therefore remain poorly known across the entire geographic range, even in otherwise well-studied taxa. 2. We surveyed populations of the trimorphic damselfly Ischnura elegans in Cyprus, which is the southern range limit in Europe of this widespread insect species. Females of I. elegans occur in three discrete and heritable colour morphs, which vary in suites of phenotypic traits. One of these female morphs is a male-mimic that avoids excessive male-mating harassment by its male-like appearance, and which is more cold-tolerant than the two other morphs. 3. In contrast to the situation in northern Europe, these male-mimicking females are the minority morph in Cyprus, representing only about 5% of all females. Male mimics also have lower mating rates than alternative female morphs. 4. Individuals in Cyprus are relatively small in comparison to the reported European range for body size, consistent with Bergman's rule. 5. Finally, populations of I. elegans on the island have the longest flight period known in Europe, and there is only partial evidence for seasonality in flight activity. 6. These results underscore the benefits of considering the entire range of environmental conditions encountered by insect species when conducting evolutionary ecology research.
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