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- Söderlind, Lina, 1982-, et al.
(author)
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Effects of sequential diets in the comma butterfly, Polygonia c-album: testing predictions from gene expression
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Other publication (other academic/artistic)abstract
- Differential gene expression, depending on host plant diet, has been found in the larval mid-gut of the polyphagous butterfly Polygonia c-album. Expression similarities between the hosts elm/sallow and between elm/stinging nettle suggest that there are special patterns of genes for utilizing trees and others for urticalean rosids. In order to assess the importance of different genes tailored to host use, we investigated the costs of switching larval diet. Negative effects were expected to be more pronounced when switching between nettle/sallow than between elm/nettle (urticalean rosids) or elm/sallow (trees) since similarities in mid-gut gene expression are fewer. However, larvae seemed surprisingly good at adjusting to new environments. Although costs were found after a single switch from sallow to nettle in the 3rd instar as well as on a daily basis the results were not consistent. More surprisingly, we found evidence that costs are involved with a single diet switch to elm. Results suggest rapid physiological adjustment to the new environment, signifying that the induced gene expression is reversible or at least does not seem to inhibit the induction of another gene complex.
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| 2. |
- Söderlind, Lina, 1982-
(author)
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Life-history consequenses of host plant choice in the comma butterfly
- 2012
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Doctoral thesis (other academic/artistic)abstract
- There is much evidence that herbivory is a key innovation for the tremendous success of insect. In this thesis I have investigated different aspects of host plant utilization and phenotypic plasticity using the polyphagous comma butterfly, Polygonia c-album. Even though external conditions affect a phenotypic plastic response, the outcome is often influenced by a genetic background which may differ among populations. In Paper I we suspected the genetic background to seasonal polymorphism to be X-linked. However, results from interspecific hybridization between two populations suggested that diapause response is instead inherited in a mainly autosomally additive fashion, with a possible influence of sexual antagonism on males. In Paper II we showed that female oviposition preference is not a plastic response influenced by larval experience, but has a genetic background coupled to host plant suitability. Further, there is a strong individual correlation between larval host plant acceptance and female host plant specificity (Paper III). We believe this to be a larval feed-back genetically linked to female host specificity: offspring to ‘choosy’ specialist mothers benefit by remaining on the original host while offspring to less discriminating generalist mothers should risk inspecting the surroundings, thus compensating for potential poor female choice. In the larval mid-gut, genes are differentially expressed depending on host plant diet (Paper IV). Therefore, we expected to find fitness consequences of host plant switch. However, although growth rate was affected in a few treatments, larvae were generally surprisingly good at adjusting to new diets (Paper V). To conclude, host plant choice in both female and larval life stage is connected to performance. Combined with increased understanding about the plastic response to diet intake and seasonal polymorphism we have gained further insights into the processes of local adaptations and speciation in the Lepidoptera.
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| 3. |
- Söderlind, Lina, 1982-, et al.
(author)
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When mother does not know best : Contrasting host plant choice across life stages in individuals of the comma butterfly
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Other publication (other academic/artistic)abstract
- Since host plant choice is often crucial for the fitness of herbivorous insects we investigated if individual variation in such decisions is consistent throughout life. In the comma butterfly, Polygonia c-album, (Nymphalidae, Nymphalini) newly hatched larvae and adult females have been found to rank hosts plants similarly, suggesting that the host plant recognition mechanisms could be preserved through metamorphosis. We measured preference for Urtica dioica relative to Salix cinerea when the plants were encountered by the same individuals in the two different life stages, finding no relationship between the two measurements. This was however found when we instead measured acceptance of a suboptimal host: First instar larvae were placed on the suboptimal S. cinerea, and were scored as to whether they accepted this host or if they instead moved to feed on the generally more preferred host U. dioica. The same individuals were then tested once more as ovipositing females, in a cage setup arranged so that females would encounter the low-ranked hosts S. cinerea and Betula pubescens more often than the high-ranked host U. dioica.Individuals that chose to abandon S. cinerea as larvae differed in oviposition behaviour later in life from those that accepted this low-ranked host, but did so by laying a higher proportion eggs on the low-ranked hosts as adults. We interpret this initially unexpected result as a result of possible genetic correlation between female host-plant specificity and larval acceptance for the plant chosen by their mother: Offspring of ‘choosy’ specialist mothers have a strong tendency to remain on their original host, whereas less discriminating generalist mothers beget larvae with lower acceptance for their original plant when it is suboptimal. Ecologically, this presents a further explanation for how a generalist oviposition strategy can be sustained since larval mobility to some extent compensates for poor female choice.
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