| The Nice Award ceremony and Plenary lecture will take place at 9:00 AM on Friday, 21 May 2010, in Albright Auditorium. This will be the first event on the Scientific Program.
Abstract:
Margaret Nice studied cowbirds and their effects on song sparrows. We draw on her work to ask some general questions about brood parasitism in birds: what is the impact of brood parasitism on the nesting hosts? Are the brood parasites generalists or specialists on their hosts? How has their specialization affected their evolution and speciation? How did brood parasitism evolve? We briefly consider the cowbirds and cuckoos, and then we describe our studies of the African brood-parasitic finches, especially the indigobirds. The brood-parasitic finches have less effect on their host brood than cowbirds (cuckoos have the greatest impact) and the young finches grow up and fledge with the host nestlings. Most Vidua finches are species-specific on certain estrildid finches, the males mimic the songs of their host species, and the nestlings mimic the host nestlings. In the field the females are attracted to mate with a male indigobird that mimics her host species. We used molecular methods to discriminate between two hypotheses of the origin of specific associations of brood parasite and host: (1) co-speciation of parasite and host, and (2) later colonization and host switch by the parasite. We report a natural population of an indigobird that has switched to a new host species. We used experimental cross-fostering tests to find the basis of learning and imprinting in the indigobirds in male song mimicry, in female choice of males that mimicked their own host species, and in female choice of species nests to parasitize. We also cross-fostered between the estrildid finches to find whether the hosts could raise young that did not match the host young, as expected if the indigobirds have shifted to new host species they did not mimic. Field observations, molecular studies and behavior experiments all indicate most of the 20 species of brood-parasitic finches are the result of host switch and later mimetic adaptation. Finally, we briefly consider a test of Darwin's explanation for the origin of brood parasitism. |
