The hypothesis that coelacanth is the closest living relative of tetrapods 3 was rejected based on three genome-scale approaches

TL;DR

This study used genome-scale analyses to evaluate hypotheses about tetrapod origins and found that coelacanth is unlikely to be the closest relative of tetrapods, challenging long-standing beliefs.

Contribution

It provides comprehensive genome-scale evidence rejecting the coelacanth-tetrapod close relationship hypothesis.

Findings

Coelacanth is not the closest relative of tetrapods.

Genome-scale approaches consistently reject the coelacanth-tetrapod hypothesis.

Multiple phylogenetic methods support the same conclusion.

Abstract

Since its discovery of the living fossil in 1938, the coelacanth (Latimeria chalumnae) has generally been considered to be the closest living relative of the land vertebrates, and this is still the prevailing opinion in most general biology textbooks. However, the origin of tetrapods has been the subject of intense debate for decades. The three principal hypothesis (lungfish-tetrapod, coelacanth-tetrapod, or lungfish-coelacanth sister group) have been proposed. We used the maximum gene-support tree approach to analyze 43 nuclear genes encoding amino acid residues, and compared the results of concatenation and majority-rule tree approaches. The results inferred with three common phylogenetic methods and three genome-scale approaches consistently rejected the hypothesis that the coelacanth is the closest living relative of tetrapods.