Mimicry and speciation in Africa's parasitic finches
Postdoctoral Fellow Dr Gabriel Jamie will present the Department of Biological Sciences seminar with a talk entitled, "Mimicry and speciation in Africa's parasitic finches".
Gabriel is based at the University of Cambridge but has close ties to the FitzPatrick Institute as he is working with our own Prof Claire Spottiswoode
Adaptive radiations provide windows into the processes that generate, limit and diminish biodiversity. While some lineages radiate into hundreds of species, others are much less speciose. Why such variation exists remains poorly understood. The indigobirds and whydahs (genus Vidua) of Africa provide an excellent system through which to understand the factors shaping adaptive radiations. Vidua are brood parasites, each specialising on a different host in the grassfinch family (Estrildidae). Nestling estrildids have ornamented and species-specific appearances important for soliciting parental care. Speciation and host colonisation are closely linked in Vidua because their mating traits and host preferences are determined by their early host environment. To explain the Vidua radiation we must therefore understand why some estrildid finch species have been successfully colonised and others not. Using field experiments and comparative analyses, I investigate the factors shaping the Vidua radiation. I present quantitative evidence for host-specific adaptation by nestling Vidua, showing that they mimic their host’s appearance, begging calls and postural movements to obtain food from host parents. Through transfer experiments, I test what limits host colonisation by Vidua in the wild and demonstrate that nestling Vidua develop their mimetic traits innately rather than plastically through interactions with their hosts. Finally, using a comparative analysis, I examine the underlying drivers of estrildid chick morphology to explain the origins of the niches into which Vidua have diversified. Together, these results suggest that the Vidua radiation can be understood through the roles of habitat preferences, the complex and phylogenetically-conserved displays of host nestlings, the discriminatory behaviour of estrildid parents against mismatching chicks and the absence of adaptive plasticity in parasite begging displays.