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, 10 (3), 967-975

Molecular Footprints of Aquatic Adaptation Including Bone Mass Changes in Cetaceans


Molecular Footprints of Aquatic Adaptation Including Bone Mass Changes in Cetaceans

Xuming Zhou et al. Genome Biol Evol.


Cetaceans (whales, dolphins, and porpoises) are a group of specialized mammals that evolved from terrestrial ancestors and are fully adapted to aquatic habitats. Taking advantage of the recently sequenced finless porpoise genome, we conducted comparative analyses of the genomes of seven cetaceans and related terrestrial species to provide insight into the molecular bases of adaptation of these aquatic mammals. Changes in gene sequences were identified in main lineages of cetaceans, offering an evolutionary picture of cetacean genomes that reveal new pathways that could be associated with adaptation to aquatic lifestyle. We profiled bone microanatomical structures across 28 mammals, including representatives of cetaceans, pinnipeds, and sirenians. Subsequent phylogenetic comparative analyses revealed genes (including leptin, insulin-like growth factor 1, and collagen type I alpha 2 chain) with the root-to-tip substitution rate significantly correlated with bone compactness, implicating these genes could be involved in bone mass control. Overall, this study described adjustments of the genomes of cetaceans according to lifestyle, phylogeny, and bone mass.


<sc>Fig</sc>. 1.
Fig. 1.
—Gene families and aquatic adaptations in cetacean genomes. (a) Phylogenetic tree and divergence times estimated for the cetaceans and their relatives. Numbers associated with each branch designate the number of gene families that have expanded (red) and contracted (blue) since the split from the common ancestor. (b) Phylogenetic tree of PRDX1 family in mammals showing expanded PRDX1 in cetaceans (highlighted by blue background). Positions of introns along the protein sequence are shown with black lines. (c) Phylogenetic tree of the GPx family in mammals showing expanded GPX1 sequences in cetaceans.
<sc>Fig</sc>. 2.
Fig. 2.
—Distinct substitutions of FSHR in marine mammals and copy number variation of OGT gene in cetaceans. (a) Alignment of FSHR (Follicle Stimulating Hormone Receptor) residues under positive selection in cetaceans. Unique substitutions identified in marine mammals are shown in blue (cetaceans), green (walrus and seal), and pink (manatee). (b) Mammalian phylogeny was used to represent the number of OGT (O-Linked N-Acetylglucosamine (GlcNAc) Transferase) gene uncovered in the cetacean genomes. (c) A schematic map showing the gene structure and sequence variation of OGT gene in cetacean genomes.
<sc>Fig</sc>. 3.
Fig. 3.
—Root-to-tip dN/dS correlates with global compactness of ribs across 28 mammals. (a) Diagrammatic sketch showing bone microanatomy of the rib and parameters measured in this study. (b) Variation in global compactness of ribs across 28 mammals in a phylogenetic context. Representatives from marine, terrestrial, and flying mammals are in green, black, and red, respectively. (c) Root-to-tip dN/dS of genes LEP (top panel) and IGF1 (bottom panel) negatively correlates with global compactness. Points are colored according to taxonomical orders (same color scheme as in b).
<sc>Fig</sc>. 4.
Fig. 4.
—Root-to-tip dN/dS from 350 bone-associated genes that correlate with the bone microstructure of ribs in 27 mammals. (a) Phylogenetic tree for 27 species with bone section bone microstructure and histogram of five bone parameters. (b) Scatter plot of significant relationships between S, Cc, and root-to-tip values. (c) Positively selected sites for Cetaceans, bats, and manatees.

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    1. Ackert-Bicknell CL. 2012. HDL cholesterol and bone mineral density: is there a genetic link? Bone 502:525–533. - PMC - PubMed
    1. Amson E, de Muizon C, Laurin M, Argot C, de Buffrénil V. 2014. Gradual adaptation of bone structure to aquatic lifestyle in extinct sloths from Peru. Proc Biol Sci. 2811782:20140192.. - PMC - PubMed
    1. Barnes LG. 1984. Fossil odontocetes (Mammalia: cetacea) from the Almejas Formation, Isla Cedros, Mexico. PaleoBios 42:1–46.
    1. Beau I, et al. , 1998. A novel phenotype related to partial loss of function mutations of the follicle stimulating hormone receptor. J Clin Invest. 1027:1352–1359. - PMC - PubMed
    1. Berta A, Sumich JL. 1999. Marine mammals Evolutionary biology. San Diego (CA: ): Academic Press.

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