Patterns of adaptation in island birds worldwide

Dr Rita Covas, from CIBIO, University of Porto, Portugal, will present a seminar entitled, "Patterns of adaptation in island birds worldwide".

The shared characteristics of island environments, such as impoverished biotas and less-seasonal climates, are thought to trigger specific adaptations by organisms. Birds make very good island colonisers, and are among the best studied groups. However, few broad-scale systematic analyses have examined patterns of evolution in island birds and our understanding of which traits are affected by the ‘insularity syndrome’ remains weak. We have been studying patterns of adaptation in reproductive life histories and morphology in island birds worldwide. Results show that insularity favours a slower pace of life in birds, with reduced fecundity, extended developmental periods, and an increase in the frequency of cooperative breeding. Reduced species diversity on islands (including the reduced number of predators and parasites) and reduced seasonality appear to play a prominent role in life history change. Parallel changes in morphological traits include changes in wing and leg shape, (broader wings and longer tarsi) and larger skull size relative to body mass. We found support also for the ‘island rule’ in island birds, but the effect is not pronounced, possibly due to the high number of extinct large flightless birds that were not included in our analyses. Finally, we found reduced colouration in island birds worldwide. Colour changes appear to arise from a reduced need for species recognition and relaxation of sexual selection pressure on islands. However, the factors underlying the changes documented here probably arise from an interaction of different ecological and genetic factors and ongoing work is investigating some of the mechanisms involved.


Wednesday, December 7, 2016 - 13:00

Niven Library, John Day Building, Upper Campus, UCT