Gene Loss

Publication Details

Identifier: JB_CBH17H

Curator: Gonçalo Themudo

DOI: 10.1016/j.cub.2021.02.057

PMID: 33798433

Title:

Genomic and anatomical comparisons of skin support independent adaptation to life in water by cetaceans and hippos.

Abstract:

The macroevolutionary transition from terra firma to obligatory inhabitance of the marine hydrosphere has occurred twice in the history of Mammalia: Cetacea and Sirenia. In the case of Cetacea (whales, dolphins, and porpoises), molecular phylogenies provide unambiguous evidence that fully aquatic cetaceans and semiaquatic hippopotamids (hippos) are each other's closest living relatives. Ancestral reconstructions suggest that some adaptations to the aquatic realm evolved in the common ancestor of Cetancodonta (Cetacea + Hippopotamidae). An alternative hypothesis is that these adaptations evolved independently in cetaceans and hippos. Here, we focus on the integumentary system and evaluate these hypotheses by integrating new histological data for cetaceans and hippos, the first genome-scale data for pygmy hippopotamus, and comprehensive genomic screens and molecular evolutionary analyses for protein-coding genes that have been inactivated in hippos and cetaceans. We identified eight skin-related genes that are inactivated in both cetaceans and hippos, including genes that are related to sebaceous glands, hair follicles, and epidermal differentiation. However, none of these genes exhibit inactivating mutations that are shared by cetaceans and hippos. Mean dates for the inactivation of skin genes in these two clades serve as proxies for phenotypic changes and suggest that hair reduction/loss, the loss of sebaceous glands, and changes to the keratinization program occurred ∼16 Ma earlier in cetaceans (∼46.5 Ma) than in hippos (∼30.5 Ma). These results, together with histological differences in the integument and prior analyses of oxygen isotopes from stem hippopotamids ("anthracotheres"), support the hypothesis that aquatic skin adaptations evolved independently in hippos and cetaceans.

Last update:

28-10-2024

Associated Glosses (230 results)

GlossID	Species	Symbol	Gene Loss Mechanism	Loss Type	Lineage Specific	Citation
GL_D6V7CY	Hippopotamus amphibius	OR10J1	Other	Full	No	10.1016/j.cub.2021.02.057
GL_DAZSJW	Tursiops truncatus	ABCC11	LOF (frameshift, premature stop, ss)	Full	Cetacea	10.1016/j.cub.2021.02.057
GL_DK9Q9Y	Tursiops truncatus	TCP11X2	Other	Full	No	10.1016/j.cub.2021.02.057
GL_DKDYQT	Balaenoptera acutorostrata	CNBD1	Other	Full	No	10.1016/j.cub.2021.02.057
GL_DPOJC7	Physeter catodon	ACTBL2	Other	Full	No	10.1016/j.cub.2021.02.057
GL_DRNF3V	Hexaprotodon liberiensis	ALOX15	LOF (frameshift, premature stop, ss)	Full	Hippopotamidae	10.1016/j.cub.2021.02.057
GL_DV2UTP	Lagenorhynchus obliquidens	MOGAT3	Other	Full	Cetacea	10.1016/j.cub.2021.02.057
GL_DZALVN	Orcinus orca	C17orf78	Other	Full	No	10.1016/j.cub.2021.02.057
GL_E2GXSB	Hippopotamus amphibius	OR9A4	Other	Full	No	10.1016/j.cub.2021.02.057
GL_E7Z0EV	Tursiops truncatus	KRT2	Gene deletion	Full	No	10.1016/j.cub.2021.02.057