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| 2. |
- Lundhagen, Anna, et al.
(författare)
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Are peripheral populations special? Congruent patterns in two butterfly species
- 2009
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Ingår i: Ecography. - Malden : Wiley-Blackwell. - 0906-7590 .- 1600-0587. ; 32:4, s. 591-600
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Tidskriftsartikel (refereegranskat)abstract
- Populations at range margins may be genetically different from more central ones for a number of mutually non-exclusive reasons. Specific selection pressures may operate in environments that are more marginal for the species. Genetic drift may also have a strong effect in these populations if they are small, isolated and/or have experienced significant bottlenecks during the colonisation phase. The question if peripheral populations are special, and if yes then how and why, is of obvious relevance for speciation theory, as well as for conservation biology. To evaluate the uniqueness of populations at range margins and the influence of gene flow and selection, we performed a morphometric study of two grassland butterfly species: Coenonympha arcania and C. hero (Lepidoptera: Nymphalidae). The samples were collected from Swedish populations that are peripheral and isolated from the main area of the species distributions and from populations in the Baltic states that are peripheral but connected to the main area of the species distributions. These samples were compared to those from central parts of the species distributions. The isolated populations in both species differed consistently from both peripheral and central populations in their wing size and shape. We interpret this as a result of selection caused by differences in population structure in these isolated locations, presumably favoring different dispersal propensity of these butterflies. Alternative explanations based on colonisation history, latitudinal effects, inbreeding or phenotypic plasticity appear less plausible. As a contrast, the much weaker and seemingly random among-region differences in wing patterns are more likely to be ascribed to weaker selection pressures allowing genetic drift to be influential. In conclusion, both morphological data and results from neutral genetic markers in earlier studies of the same system provide congruent evidence of both adaptation and genetic drift in the isolated Swedish populations of both species.
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| 3. |
- Nielsen, Matthew, et al.
(författare)
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Evolution of butterfly seasonal plasticity driven by climate change varies across life stages
- 2023
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Ingår i: Ecology Letters. - 1461-023X .- 1461-0248. ; 26:9, s. 1548-1558
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Tidskriftsartikel (refereegranskat)abstract
- Photoperiod is a common cue for seasonal plasticity and phenology, but climate change can create cue-environment mismatches for organisms that rely on it. Evolution could potentially correct these mismatches, but phenology often depends on multiple plastic decisions made during different life stages and seasons that may evolve separately. For example, Pararge aegeria (Speckled wood butterfly) has photoperiod-cued seasonal life history plasticity in two different life stages: larval development time and pupal diapause. We tested for climate change-associated evolution of this plasticity by replicating common garden experiments conducted on two Swedish populations 30 years ago. We found evidence for evolutionary change in the contemporary larval reaction norm-although these changes differed between populations-but no evidence for evolution of the pupal reaction norm. This variation in evolution across life stages demonstrates the need to consider how climate change affects the whole life cycle to understand its impacts on phenology.
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| 4. |
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| 5. |
- Nylin, Sören, 1959-, et al.
(författare)
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Geographical variation in host plant utilization in the comma butterfly: the roles of time constraints and plant phenology
- 2009
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Ingår i: Evolutionary Ecology. - Dordrecht : Springer. - 0269-7653 .- 1573-8477. ; 23, s. 807-825
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Tidskriftsartikel (refereegranskat)abstract
- What is the role of time-constraints in determining geographical variation in the resource use of organisms? One hypothesis concerning phytophagous insects predicts a local narrowing of host plant range at localities where a short development time is important (because an additional generation per season is only just possible), with increased specialization on host plants permitting fast development. To test this hypothesis, populations of the polyphagous comma butterfly (Nymphalidae: Polygonia c-album) from five European areas (localities in Norway, Sweden, England, Belgium and Spain) were sampled and the preferences of laboratory-reared female butterflies were investigated, by a choice test between Salix caprea and the fastest host Urtica dioica. The results suggest that females of both of two northern univoltine populations (time-stressed from Norway and time-relaxed from Sweden) accept the slow host S. caprea to a higher degree than females of more southern populations with partial additional generations (time-stressed). We thus found partial support for the tested hypothesis, but also conflicting results that cast doubt on its broad generality. Moreover, a split-brood investigation on Swedish stock demonstrated that larval performance is similar on S. caprea and U. dioica early in the summer, but that later in the season S. caprea is a much inferior host. This is reflected by a seasonal trend towards specialization on U. dioica and also provides a simpler explanation than the time-constraints theory for avoidance of S. caprea (and other woody hosts) in areas with two or more generations of insects per year, illustrating the importance of plant phenology as a constraint on resource use in phytophagous insects. Absolute and relative larval performance on the two hosts varied little among populations across Europe, but lower survival on S. caprea in the populations most specialized on U. dioica and related plants may be indicative of performance trade-offs.
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| 6. |
- Nylin, Sören, 1959-
(författare)
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Gradients in butterfly biology
- 2009
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Ingår i: Ecology of butterflies in Europe. - Cambridge : Cambridge University Press. - 9780521766975 ; , s. 198-216
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Bokkapitel (refereegranskat)
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| 7. |
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| 8. |
- Nylin, Sören, 1959-, et al.
(författare)
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Threat status in butterflies and its ecological correlates: how far can we generalize?
- 2009
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Ingår i: Biodiversity and Conservation. - : Springer. - 0960-3115 .- 1572-9710. ; 18, s. 3243-3267
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Tidskriftsartikel (refereegranskat)abstract
- It would be very useful for conservation biologists to be able to predict threat status from ecological characteristics of species, and past studies have shown promising results. Regarding one important threat indicator taxon, the butterflies, results from a study on Finnish species by Kotiaho et al. (Proc Natl Acad Sci USA 102:1963–1967, 2005), suggested that threatened butterflies on average have narrower niches, more restricted distributions of the larval host plants, poorer dispersal abilities and shorter flight periods. However, this study did not control for phylogenetic relatedness of species. To examine the effects of phylogenetic control, and to see how far it is possible to generalize from specific investigations, we compared the ecological characteristics of threatened and non-threatened butterfly species at two different geographical scales: Sweden and Europe. Our results illustrate the difficulties of generalizing between sites, geographical scales, scoring methods, and phylogenetic versus non-phylogenetic analyses. Controlling for phylogeny is shown to be essential. The most robust result is that threatened species have narrower habitat ranges at the local scale.
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