Common chiffchaff obvious wing bars; they include the willow, Bonelli's, wood and plain leaf warblers. The common chiffchaff has three still commonly accepted subspecies, together with some from the Iberian Peninsula, the Canary Islands, and the Caucasus which are now more often treated as full species. The common chiffchaff's English name is onomatopoeic, referring to the repetitive "chiff-chaff" song of the European subspecies. There are similar names in some other European languages, such as the Dutch "Tjiftjaf", the German "Zilpzalp" and Welsh "siff-saff". The binomial name is of Greek origin; "Phylloscopus" comes from "phyllon"/φυλλον, "leaf", and "skopeo"/σκοπεω, "to look at" or "to
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