THE UNUSUAL SPERM MORPHOLOGY OF THE EURASIAN BULLFINCH (PYRRHULA PYRRHULA) IS NOT DUE TO THE PHENOTYPIC RESULT OF GENETIC REDUCTION

摘要

The Eurasian Bullfinch (Pyrrhula pyrrhula) is unusual among passerines in that it has both an extremely unusual sperm morphology and unusually high levels of inter- and intra-male variation in sperm morphology. One possible cause of this high level of variation in sperm design is the phenotypic results of inbreeding following a bottleneck event. There are two points in time when the Eurasian Bullfinch may have been subject to a bottleneck. Many Eurasian passerines underwent a series of post-Pleistocene bottlenecks following the retreat of the glaciers. More recently, in the United Kingdom the Eurasian Bullfinch has declined severely in numbers in the past 40 years. We used universal bird microsatellite primers to directly compare the genetic diversity of the Eurasian Bullfinch with that of three fringillid finch species that display "typical" passerine sperm morphology: the European Greenfinch (Carduelis chloris), Common Chaffinch (Fringilla coelebs), and Red Crossbill (Loxia curvirostra). We found no evidence that the Eurasian Bullfinch has undergone a reduction in genetic variation that could account for its unusual sperm morphology. Alternative hypotheses, such as a relaxation in sperm competition, now warrant further investigation. Received 4 December 2009, accepted 2 May 2010.