Siberian chiffchaff Siberian chiffchaff Siberian chiffchaff ("Phylloscopus (collybita) tristis") is a leaf-warbler which is usually considered a subspecies of the common chiffchaff, but may be a species in its own right. Siberian chiffchaff breeds in Siberia east of the Pechora River and winters in the lower Himalayas. It is also regularly recorded in western Europe in winter, and it is likely that the numbers involved have been underestimated due to uncertainties over identification criteria, lack of good data and recording policies (Sweden and Finland only accept trapped birds). Because of their unfamiliar appearance, British records in the 1950s and 1960s were originally
Genomic evolution of birds or two cone opsin genes. Birds also seem to have lost the functionality of their right ovary. There are two ovary development-related genes, MMP19 and AKR1C3, that have disappeared in birds. The fact that a high number of genes related to spermatogenesis are evolving fast (which does not happen in those related to ovogenensis) suggest that males undergo a stronger selective pressure. The abundance of genomic data available nowadays has enabled research to elucidate the early evolution and divergence of bird groups, and has produced a much more detailed phylogenetic tree. Genomic research has shown that in order to make