| 1. |
- Nylin, Sören, et al.
(författare)
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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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Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 40:3, s. 307-315
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Tidskriftsartikel (refereegranskat)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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| 2. |
- Söderlind, Lina, 1982-, et al.
(författare)
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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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Annan publikation (övrigt vetenskapligt/konstnärligt)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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