Gamete Recognition Gene Divergence Yields a Robust Eutherian Phylogeny across Taxonomic Levels

Abstract

The extraordinary morphological diversity among extant mammals poses a challenge for studies of speciation, adaptation, molecular evolution, and reproductive isolation. Despite the recent wealth of molecular studies on mammalian phylogenetics, uncertainties remain surrounding both ancestral and more recent divergence events that have proven difficult to resolve. Multi-gene datasets, especially including genes that are highly divergent, often provide increased support for higher-level affinities within Mammalia; however, such analyses require vast amounts of genomic sequence data and at times, intensive, high-performance computational effort. Furthermore, despite the large-scale efforts dedicated to comprehensive, multi-gene phylogenetic analyses using a combination of mitochondrial, nuclear, and other sequences (e.g., tRNA, ultra-conserved elements, and transposable elements), many relationships across Mammalia remain highly controversial. To offer another approach and provide a phylogenetic solution to this longstanding issue, here we present a phylogenetic tool based on a single reproductive molecular marker, zonadhesin (gene: Zan), one of two known mammalian speciation genes, which encodes the rapidly evolving sperm protein zonadhesin that mediates species-specific adhesion to the egg and thereby promotes reproductive isolation among placental mammals (Eutheria). Topological comparison of Zan Maximum Likelihood phylogenies to a nearly complete mammalian supertree confirmed Zan’s striking phylogenetic utility and resolution at both deeper and more terminal nodes in the placental mammalian phylogeny. This single gene marker yielded an equivalent and/or superiorly supported topology in comparison to a supertree generated using DNA sequences from a supermatrix of 31 genes from 5911 species (extinct and extant). Resolution achieved with this new phylogenetic approach provides unique insights into the divergence of both early and recent mammalian radiations. Finally, and perhaps most importantly, the utility of zonadhesin as a singular molecular marker was especially useful in clades where sufficient taxon sampling is impossible to achieve, and where only a subset of members of the mammalian species tree is available. The eutherian relationships presented here provide a foundation for future studies in the reconstruction of mammalian classifications, including reproductive isolation, hybridization, and biodiversification of species.

Genetic characterization of the prion protein gene in camels (Camelus) with comments on the evolutionary history of prion disease in Cetartiodactyla

“…Given the phylogenies obtained from supertree analyses ( Bininda-Emonds et al, 2007 ; Upham, Esselstyn & Jetz, 2019 ) and a mammalian speciation gene ( Roberts et al, 2022 ; Roberts et al, 2023 ), the common vampire bat ( Desmodus rotundus ) was designated as the outgroup species. Representative individuals ( n = 302) from the Order Perissodactyla ( i.e., Ceratotherium , Equus , etc .)…”

“…A BI analysis was utilized to visualize both nucleotide and amino acid topologies of PRNP . The armadillo ( Dasypus novemcinctus ) was designated as the outgroup species based on phylogenies obtained from supertree analyses ( Bininda-Emonds et al, 2007 ; Upham, Esselstyn & Jetz, 2019 ) and a speciation gene ( Roberts et al, 2022 ; Roberts et al, 2023 ). Additional taxa included representatives of the Orders Carnivora ( n = 48), Order Chiroptera ( n = 20), Order Eulipotyphla ( n = 6), Order Lagomorpha ( n = 1), Order Pholidota ( n = 1), and Primates ( n = 1) as well as taxa from the previous phylogenetic analyses, totaling a dataset with 578 sequences.…”