Geographical features are the predominant driver of molecular diversification in widely distributed North American whipsnakes

Abstract

Allopatric divergence following the formation of geographical features has been implicated as a major driver of evolutionary diversification. Widespread species complexes provide opportunities to examine allopatric divergence across varying degrees of isolation in both time and space. In North America, several geographical features may play such a role in diversification, including the Mississippi River, Pecos River, Rocky Mountains, Cochise Filter Barrier, Gulf of California and Isthmus of Tehuantepec. We used thousands of nuclear single nucleotide polymorphisms (SNPs) and mitochondrial DNA from several species of whipsnakes (genera Masticophis and Coluber) distributed across North and Central America to investigate the role that these geographical features have played on lineage divergence. We hypothesize that these features restrict gene flow and separate whipsnakes into diagnosable genomic clusters. We performed genomic clustering and phylogenetic reconstructions at the species and population levels using Bayesian and likelihood analyses and quantified migration levels across geographical features to assess the degree of genetic isolation due to allopatry. Our analyses suggest that (i) major genetic divisions are often consistent with isolation by geographical features, (ii) migration rates between clusters are asymmetrical across major geographical features, and (iii) areas that receive proportionally more migrants possess higher levels of genetic diversity. Collectively, our findings suggest that multiple features of the North American landscape contributed to allopatric divergence in this widely distributed snake group.

Distributional patterns of Neotropical seasonally dry forest birds: a biogeographical regionalization

“…The clear differentiation of the groups on both sides of the Tehuantepec Isthmus (north‐western Mexico, Yucatan Peninsula and Central America; Fig. ), as well as the subdivisions observed within the northern Mexican regions [Sonora‐Sinaloa (SS), northern Oaxaca (SP) and Tamaulipas–Veracruz (TV) areas] might be explained by higher diversification rates compared to other dry forest areas, as detected for example in the hummingbird Amazilia cyanocephala (Rodríguez‐Gómez et al., ; O'Connell et al., ). Although the age of Mesoamerican NSDFs is not known, the fossil record and dated phylogenies suggest a Miocene–Pliocene age at least in north‐western Mexico (Becerra, ).…”

“…The Baja California's NSDF In regional cladograms the Cape of Baja California forms a distinct unit, which supports the idea of a somewhat independent biogeographical history, as has been suggested in previous avian regionalizations. Isolation of the NSDF in the Cape region from those in western Mexico (5.5-4.0 Mya) by the Gulf of California has promoted the differentiation and a high degree of endemism associated with the Cape of diverse groups, including mammals, birds, snakes and insects (Grismer, 2000;Rojas-Soto et al, 2003;R ıos-Muñoz and Navarro-Sig€ uenza, 2012;O'Connell et al, 2017). However, given the closest affinities of avian species with the nearby continent at the northern portion of the Peninsula (Rojas-Soto et al, 2003), it seems clear that the Cape avifauna originated through a terrestrial route from the northern to the southern tip of the Baja California Peninsula (Rojas-Soto et al, 2003;O'Connell et al, 2017).…”

Environmental heterogeneity and not vicariant biogeographic barriers generate community‐wide population structure in desert‐adapted snakes

“…Environmental variation for each collecting locality for all species was extracted from this set of uncorrelated variables.We used three different resistance surfaces that may better reflect patterns of genomic divergence than pure geographic distance; these are resistance around major rivers of southwestern North America, elevation, and potential geographic distributions based on ecological niche models (ENMs). Major rivers were selected given that numerous studies have suggested that the Pecos River, the Rio Grande and the Colorado River (e.g.,Graham et al, 2015;Myers et al, 2019;O'Connell et al, 2017; Wood et al, 2013) are barriers to gene flow. Elevation was selected as a resistance surface because the Cochise Filter Barrier is often associated with the Western Continental Divide(Castoe, Spencer, & Parkinson, 2007), a high elevation region between major watersheds in North America and because the Central Mexican Plateau has been associated with lineage divergence in previous studies of the same taxa(Schield et al, 2018).…”

New record and range expansion of Masticophis lateralis (Hallowell, 1853) (Squamata, Colubridae) into western Baja California Sur, Mexico

“…Studies have demonstrated considerable flexibility in thermoregulatory behavior in M. lateralis as well as distinct species complexes within Masticophis due to vicariance events and barriers of isolation within North America (Hammerson 1979, O'Connell et al 2017). This new record expands the range of M. lateralis into the westward plain desert of Baja California Sur; this is a new isolated environment compared to former records.…”