Abstracts (first author)

Talk 

Evolution on the move: adaptation to use a widespread host associated with responses to climate change in the UK butterfly Aricia agestis

Author(s): Bridle J, Buckley J

Summary:

A species’ geographical ranges typically consists of many populations differently adapted to local ecological conditions, such as the availability of particular hosts or prey. Specialization on localized resources could prevent species from colonizing new sites where the same resources are not available, limiting their capacity to track climatic changes. Consistent with this, we observe that rapid evolution of host preference as well as morphology related to increased dispersal has been associated with recent range expansion of the Brown Argus butterfly, Aricia agestis. While butterflies in long-established parts of their range exhibit local adaptation, usually showing increased preference for laying their eggs on the locally most abundant host plants, butterflies in recently-colonized areas show a consistent preference for a host plant species (Geranium molle) that is geographically widespread in the region of expansion, despite being locally rare. Reciprocal transplant experiments support these data, and show that recent colonists have lost local adaptations present in the established part of the range. Our data suggest that future anthropogenic warming can be expected to bring about a major restructuring of patterns of local adaptation, and may limit the potential for popuations to continue to evolve in the future.



Abstracts (coauthor)

Summary:

Understanding why populations fail to adapt to environmental change is critical to explain the formation of species’ range limits, and to predict the conditions under which populations will be able to evolve in response to climate change and habitat loss. Two hypotheses have been proposed to explain why adaptation fails in response to environmental change: (1) A lack of additive genetic variance in key traits or trait combinations inhibits a response to selection, and (2) Local adaptation in peripheral populations is swamped by gene flow from larger populations adapted to conditions at the centre of the range. Several theoretical models provide insights into the circumstances under which adaptation is expected to occur, but empirical tests of these predictions in wild populations are rare. We examined spatial changes in the mean and additive genetic variance of ecologically important traits of the rainforest specialist Drosophila birchii along repeated altitudinal gradients, to evaluate evidence for these competing hypotheses about limits to adaptation. We found little evidence for adaptive divergence in stress traits (cold tolerance, heat tolerance, desiccation resistance) or morphological traits (thorax length, wing size) at any transect, despite abundant genetic variance in most traits and populations. At two transects, male reproductive success was higher in high altitude populations than low altitude populations. Our results suggest that gene flow along altitudinal gradients is likely to be an important factor limiting adaptive divergence. However, we are also investigating the possibility that trade-offs between stress tolerance and reproductive success may constrain evolution at the range margins of this species.

Contacts

Chairman: Octávio S. Paulo
Tel: 00 351 217500614 direct
Tel: 00 351 217500000 ext22359
Fax: 00 351 217500028
email: mail@eseb2013.com

Address

XIV Congress of the European Society for Evolutionary Biology

Organization Team
Department of Animal Biology (DBA)
Faculty of Sciences of the University of Lisbon
P-1749-016 Lisbon
Portugal

Website

Computational Biology & Population Genomics Group 
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