A relative shift in cloacal location repositions external genitalia in amniote evolution.

ABSTRACT: The move of vertebrates to a terrestrial lifestyle required major adaptations in their locomotory apparatus and reproductive organs. While the fin-to-limb transition has received considerable attention, little is known about the developmental and evolutionary origins of external genitalia. Similarities in gene expression have been interpreted as a potential evolutionary link between the limb and genitals; however, no underlying developmental mechanism has been identified. We re-examined this question using micro-computed tomography, lineage tracing in three amniote clades, and RNA-sequencing-based transcriptional profiling. Here we show that the developmental origin of external genitalia has shifted through evolution, and in some taxa limbs and genitals share a common primordium. In squama

SUBMITTER: Tschopp P 

PROVIDER: S-EPMC4294627 | biostudies-literature | 2014 Dec

REPOSITORIES: biostudies-literature