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- Cassel, Anna, et al.
(author)
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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
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In: Conservation Biology. - : Blackwell Science Publishing. - 0888-8892 .- 1523-1739. ; 15:6, s. 1667-1673
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Journal article (peer-reviewed)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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- Gotthard, Karl, et al.
(author)
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Individual state controls temperature dependence in a butterfly (Lasiommata maera)
- 2000
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In: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 267:1443, s. 589-93
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Journal article (peer-reviewed)abstract
- In ectotherms there is typically a strong and positive correlation between growth rate and ambient temperature when food is not limiting. However, the exact relationship between growth rate and temperature varies among populations in many species. As a consequence, it has been suggested that selection for a rapid increase in growth rate with temperature should be stronger in populations experiencing a high degree of time-stress, compared with populations experiencing little time-stress. In the present study we take this adaptive hypothesis further and investigate if variation in time-stress among individuals of a single population may affect the relationship between growth rate and ambient temperature. Time-stress was manipulated by rearing larvae of the butterfly Lasiommata maera in different day-length regimes. The results show that individuals experiencing a higher degree of time-stress increase their growth rates more in higher temperatures compared with individuals under less time-stress. Hence, the adaptive hypothesis was supported and the relationship between growth rate and temperature was highly state dependent. These findings may be of general importance for understanding the evolution of life histories in seasonal environments.
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