How climate change affects evolution
How quickly can natural populations respond to human-induced selection pressures? A major aspect of predicting how species evolve in response to external pressures is an understanding of genetic adaptation and the ability of an organism to change its phenotype (known as phenotypic plasticity) and the associated molecular changes. Phenotype can defined as a composite of an organism's observable physical traits. Although phenotypic plasticity might play an important role in how a species evolves, evolution ultimately requires adaptive changes in gene frequencies. The 'Genetic and epigenetic basis of adaptation to climate change' (GEBACC) project tested the ability of wild populations to respond to anthropogenic environmental change. Frogs are particularly sensitive to environmental fluctuations. Therefore, the ecologically relevant trait of locomotion was studied in the wild-caught frog Xenopus tropicalis, a species commonly used as a model organism in developmental biology and genetics. Habitat destruction has caused a dramatic decline in frogs and other amphibians, particularly in tropical forests. Such changes are expected to favour those frogs that are able to move to suitable new habitats. GEBACC recreated this selection event in the laboratory by selectively breeding X. tropicalis over several generations for increased endurance under different temperature conditions. Genetic, epigenetic, physiological, biochemical and morphological changes in response to selection were to be monitored. The impact of selection will also be examined for another trait, immunity, given that natural populations always face a number of threats simultaneously and amphibians around the world are currently at risk from an infectious disease known as chytridiomycosis. This will enable scientists to determine to what extent the response to one selection pressure affects the response to another. Due to initial difficulties with X. tropicalis, the model system was changed to the butterfly Pieris brassicae, which was phenotyped and bred for the trait of endurance. The insects were examined for the association between expression patterns of associate genes and differences in phenotype, together with the heritability of endurance. Project work has already given rise to four publications. GEBACC's highly integrative and multidisciplinary approach is crucial to gaining clearer insight into the intricacies of molecular and phenotypic responses of natural populations to environmental perturbations. The project will therefore help scientists predict how natural populations will adapt to climate change.
