On the fate of seasonally plastic traits in a rainforest butterfly under relaxed selection
Oostra, V. ; Brakefield, P.M. ; Hiltemann, Y. ; Zwaan, B.J. ; Brattström, O. - \ 2014
Ecology and Evolution 4 (2014)13. - ISSN 2045-7758 - p. 2654 - 2667.
sexual size dimorphism - bicyclus-anynana - phenotypic plasticity - reaction norms - life-history - evolutionary significance - artificial selection - geographic-variation - resource-allocation - thermal plasticity
Many organisms display phenotypic plasticity as adaptation to seasonal environmental fluctuations. Often, such seasonal responses entails plasticity of a whole suite of morphological and life-history traits that together contribute to the adaptive phenotypes in the alternative environments. While phenotypic plasticity in general is a well-studied phenomenon, little is known about the evolutionary fate of plastic responses if natural selection on plasticity is relaxed. Here, we study whether the presumed ancestral seasonal plasticity of the rainforest butterfly Bicyclus sanaos (Fabricius, 1793) is still retained despite the fact that this species inhabits an environmentally stable habitat. Being exposed to an atypical range of temperatures in the laboratory revealed hidden reaction norms for several traits, including wing pattern. In contrast, reproductive body allocation has lost the plastic response. In the savannah butterfly, B. anynana (Butler, 1879), these traits show strong developmental plasticity as an adaptation to the contrasting environments of its seasonal habitat and they are coordinated via a common developmental hormonal system. Our results for B. sanaos indicate that such integration of plastic traits – as a result of past selection on expressing a coordinated environmental response – can be broken when the optimal reaction norms for those traits diverge in a new environment
Convergence and Divergence in Direct and Indirect Life-History Traits of Closely Related Parasitoids (Braconidae: Microgastrinae)
Harvey, J.A. ; Visser, B. ; Lann, C. le; Boer, J.G. de; Ellers, J. ; Gols, R. - \ 2014
Evolutionary Biology 41 (2014)1. - ISSN 0071-3260 - p. 134 - 144.
wasp venturia-canescens - sexual size dimorphism - developmental strategies - reproductive strategies - evolutionary argument - development time - egg-production - body-size - host - hymenoptera
Closely related species in nature often show similarities in suites of direct and indirect traits that reveal aspects of their phylogenetic history. Here we tested how common descent affects trait evolution in several closely related parasitoid species in the genera Cotesia and Microplitis (Hymenoptera: Braconidae: Microgastrinae) by comparing development, resource use and allocation into reproduction and maintenance. Parasitoids in these genera exhibit traits, like haemolymph feeding as larvae and external pupation that are rare in most parasitoid lineages. The growth of parasitized hosts was reduced by 90 % compared with healthy hosts, and maximum host size depended to a large extent on adult parasitoid size. Development time was longer in the more generalist parasitoids than in the specialists. Adult body mass was sexually dimorphic in all Cotesia species, with females being larger, but not in Microplitis spp. In contrast, in one of the Microplitis species males were found to be the larger sex. Egg load dynamics during the first 6 days after emergence were highly variable but egg number was typically higher in Cotesia spp. compared to Microplitis spp. Longevity in the various species was only greater in female than in male wasps in two Microplitis sp. There was a clear inverse relationship between resource use and allocation, e.g. maximum egg load and longevity, in these parasitoids. Our results reveal that adaptation to constraints imposed by host quality and availability has resulted in trait convergence and divergence at the species, genus and subfamily level.
Life-history traits of gaur Bos gaurus: A first analysis
Ahrestani, F.S. ; Iyer, S. ; Heitkonig, I.M.A. ; Prins, H.H.T. - \ 2011
Mammal Review 41 (2011)1. - ISSN 0305-1838 - p. 75 - 84.
sexual size dimorphism - population-dynamics - prey selection - southern india - bison - ungulate - ecology - buffalo - tiger - carnivores
In this first detailed analysis of gaur Bos gaurus life-history traits, data were collected from a 20-month field study in South India and from captive gaur populations. Mean age of females at first parturition was 3 years; females remained fertile beyond the age of 15 years. Adult females were three times more abundant than adult males in the wild; survival of females was greater than males beyond three years of age. Life span of both sexes has not exceeded 24 years in captivity. Gaur life-history traits are similar to those of other similar-sized Bovini species.
Quantitative genetic variation in an island population of the speckled wood butterfly (Pararge aegeria)
Windig, J.J. ; Veerkamp, R.F. ; Nylin, S. - \ 2004
Heredity 93 (2004)5. - ISSN 0018-067X - p. 450 - 454.
sexual size dimorphism - bicyclus-anynana - fluctuating asymmetry - inbreeding depression - evolutionary genetics - natural-selection - reaction norms - wing pattern - trade-offs - inachis-io
Evidence of changes in levels of genetic variation in the field is scarce. Theoretically, selection and a bottleneck may lead to the depletion of additive genetic variance (VA) but not of nonadditive, dominance variance (VD), although a bottleneck may converse VD to V A. Here we analyse quantitative genetic variation for the Speckled Wood butterfly Pararge aegeria on the island of Madeira about 120 generations after first colonisation. Colonisation of the island involved both a bottleneck and strong natural selection, changing the average value of traits. Several life history and morphological traits with varying levels of change since colonisation were analysed. In accordance with expectations, all traits except one showed relatively low levels of VA, with an average heritability (h2) of 0.078. Levels of VD for these traits were relatively high, 20-94% of total variance and on average 80% of VG. The exception was a morphological trait that probably had not experienced strong natural selection after colonisation, for which a h2 of 0.27 was found. Another interesting observation is that the population seems resistant to inbreeding effects, which may be the result of purging of deleterious alleles.