Accelerated Evolution of Limb-Related Gene Hoxd11 in the Common Ancestor of Cetaceans and Ruminants (Cetruminantia)

Abstract

Reduced numbers of carpal and tarsal bones (wrist and ankle joints) are extensively observed in the clade of Cetacea and Ruminantia (Cetruminantia). Homebox D11 (Hoxd11) is one of the important genes required for limb development in mammals. Mutations in Hoxd11 can lead to defects in particular bones of limbs, including carpus and tarsus. To test whether evolutionary changes in Hoxd11 underlie the loss of these bones in Cetruminantia, we sequenced and analyzed Hoxd11 coding sequences and compared them with other 59 HoxA and HoxD genes in a taxonomic coverage of Cetacea, Ruminantia and other mammalian relatives. Statistical tests on the Hoxd11 sequences found an accelerated evolution in the common ancestor of cetaceans and ruminants, which coincided with the reduction of carpal and tarsal bones in this clade. Five amino acid substitutions (G222S, G227A, G229S, A240T and G261V) and one amino acid deletion (G254Del) occurred in this lineage. In contrast, other 59 HoxA and HoxD genes do not show this same evolutionary pattern, but instead display a highly conserved pattern of evolution in this lineage. Accelerated evolution of Hoxd11, but not other 59 HoxA and HoxD genes, is probably related to the reduction of the carpal and tarsal bones in Cetruminantia. Moreover, we found two amino acid substitutions (G110S and D223N) in Hoxd11 that are unique to the lineage of Cetacea, which coincided with hindlimb loss in the common ancestor of cetaceans. Our results give molecular evidence of Hoxd11 adaptive evolution in cetaceans and ruminants, which could be correlated with limb morphological adaptation. KEYWORDS

Molecular mechanisms of adaptive evolution in wild animals and plants

“…The Hox (Homebox) gene family is responsible for mammalian limb development, and mutations in the gene Hoxd11 cause defects in specific bones of the limbs, including the carpal and tarsus (Davis and Capecchi, 1994;Favier et al, 1995). Distinctive amino acid substitutions (G110S and D223N) have been recorded in cetacean Hoxd11, consistent with the loss of hindlimbs in the common ancestor of cetaceans and providing molecular evidence for the adaptive evolution of Hoxd11 in cetacean limb morphology (Li et al, 2020b). Another study found that cetacean Hoxd13 has two or three more repeats of alanine residues (Wang et al, 2009).…”

First DNA sequence proof for the occurrence of bovine adenovirus types 10 and 11 in continental Europe

“…The novel type, proposed to be BAdV-11 fits into the clade of BAdV-1 and BAdV-2 having a close relation with other AdVs from ruminants (Ruminantia) and cetaceans (Cetacea). The most recent zoo taxonomic classification has combined the suborder Ruminantia and infraorder Cetacea into a common clade, named Cetruminantia(Li et al, 2020). BAdV-1, -2, -11, ovine AdV-1, -2, ibex AdV, as well as the AdVs from whale, dolphin and porpoise belong unambiguously into this AdV lineage that supposedly has coevolved with hosts encompassed by the group Cetruminantia (Figure2).…”