title: Evolutionary landscape of amphibians emerging from ancient freshwater fish inferred from complete mitochondrial genomes.
abstract: It is very interesting that the only extant marine amphibian is the marine frog, Fejervarya cancrivora. This study investigated the reasons for this apparent rarity by conducting a phylogenetic tree analysis of the complete mitochondrial genomes from 14 amphibians, 67 freshwater fishes, four migratory fishes, 35 saltwater fishes, and one hemichordate. The results showed that amphibians, living fossil fishes, and the common ancestors of modern fishes are phylogenetically separated. In general, amphibians, living fossil fishes, saltwater fishes, and freshwater fishes are clustered in different clades. This suggests that the ancestor of living amphibians arose from a type of primordial freshwater fish, rather than the coelacanth, lungfish, or modern saltwater fish. Modern freshwater fish and modern saltwater fish were probably separated from a common ancestor by a single event, caused by crustal movement.
authors.affiliation: College of Animal Science and Technology, China Agricultural University, Beijing 100193, China.
authors.forename: Xiao-Tong
authors.initials: XT
authors.lastname: Wang
authors.forename: Yan-Feng
authors.initials: YF
authors.lastname: Zhang
authors.forename: Qian
authors.initials: Q
authors.lastname: Wu
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
mesh_terms: D000663:Amphibians / Q000145:classification* / Q000235:genetics; D000818:Animals; D001001:Anura / Q000235:genetics; D005075:Biological Evolution; D005399:Fishes / Q000145:classification* / Q000235:genetics; D054629:Genome, Mitochondrial; D010802:Phylogeny