Molecular phylogeny of long-tailed shrews (genus Sorex) from México and Guatemala

Abstract

We present a molecular phylogeny of North American species of long-tailed shrews of the genus Sorex. Our focus is on Mexican and Guatemalan species to begin understanding their evolutionary relationships and to test the validity of nominal species. Seventy-seven sequences of the mitochondrial cytochrome b gene were analyzed, including 19 specimens representing nine Mexican and one Guatemalan species. Phylogenetic analyses using parsimony, maximum likelihood and Bayesian approaches revealed two major clades of North American species, all within the subgenus Otisorex. The first major clade includes S. trowbridgii and southern species (S. macrodon from Oaxaca; S. veraecrucis from Nuevo León, Michoacán, Chiapas, S. saussurei from Jalisco and Guatemala; S. veraepacis from Guerrero and Guatemala). Relatively deep branches among taxa characterize this clade and suggest that their early divergence from other North American shrews was soon after arrival of the ancestral stock from the Beringian region. The other major clade includes all other North American species of Sorex we examined, with two Mexican species, S. milleri and S. emarginatus, grouped in a subclade with the S. cinereus complex. Sorex veraecrucis is not, however, a monophyletic taxon because specimens of this nominal species were included in both the major clades. The Isthmus of Tehuantepec has likely played a role as a biogeographic barrier in the evolutionary history of Mexican shrews. This study of mitochondrial variation in southern North American shrews of the genus Sorex indicates there is substantial, previously undetected diversity that necessitates a revision of the taxonomy of S. veraecrucis and S. veraepacis.

Hidden endemism, deep polyphyly, and repeated dispersal across the Isthmus of Tehuantepec: Diversification of the White‐collared Seedeater complex (Thraupidae: Sporophila torqueola)

“…The Isthmus of Tehuantepec is a narrow continental area separating the Gulf Coast and the Pacific Ocean that is the product of a complex geologic history of tectonic uplift and sea level change over the past 6 million years since the late Miocene (Barrier, Velasquillo, Chavez, & Gaulon, ; Ferrusquía‐Villafranca, ). Periodic episodes of geographic isolation imposed by uplift of the Isthmus of Tehuantepec and glacial oscillations in sea level have served as important biogeographic events for other taxa, including freshwater fishes (Huidobro, Morrone, Villalobos, & Alvarez, ), insects (Halffter, ), snakes (Bryson, García‐Vázquez, & Riddle, ; Castoe et al., ; Daza, Castoe, & Parkinson, ), shrews (Esteva, Cervantes, Brant, & Cook, ), and other birds (Barber & Klicka, ; Cortés‐Rodríguez et al., ). The distributional patterns observed in S. torqueola and S. morelleti are similar to other Neotropical taxa that span the coastal lowlands below 1,000 m and border the Mexican mountain systems (Arbeláez‐Cortés & Navarro‐Sigüenza, ; Huidobro et al., ; Lavinia et al., ), which roughly corresponds to the Neotropical region of the established transition zones between Neotropical and Nearctic fauna in Mexico (Halffter & Morrone, ; Morrone, ).…”

“…We inferred repeated dispersal out of South America into Mesoamerica, and across the Isthmus of Tehuantepec (Figure 4) (Barrier, Velasquillo, Chavez, & Gaulon, 1998;Ferrusquía-Villafranca, 1993). Periodic episodes of geographic isolation imposed by uplift of the Isthmus of Tehuantepec and glacial oscillations in sea level have served as important biogeographic events for other taxa, including freshwater fishes (Huidobro, Morrone, Villalobos, & Alvarez, 2006), insects (Halffter, 1987), snakes (Bryson, García-Vázquez, & Riddle, 2011;Castoe et al, 2009;Daza, Castoe, & Parkinson, 2010), shrews (Esteva, Cervantes, Brant, & Cook, 2010), and other birds (Barber & Klicka, 2010;Cortés-Rodríguez et al, 2013) (Escalante, Navarro-Sigüenza, & Peterson, 1993), alongside more than 30 endemic amphibians (García, 2006), over 120 endemic nonavian reptiles (García, 2006), numerous mammals (Escalante, Szumik, & Morrone, 2009;García-Trejo & Navarro-Sigüenza, 2004), and terrestrial invertebrates (Morrone & Márquez, 2001). This region comprises the northwestern limits of the Neotropical lowlands that characterize the Mexican transition zone (Halffter & Morrone, 2017).…”

Diversification and biogeographical history of Neotropical plethodontid salamanders

“…Like bolitoglossine salamanders, shrews have a northern origin; the two main genera found in the Neotropics, Sorex and Cryptotis, are distributed from North America south to Guatemala and the northern Andes of South America, respectively. They show much lower levels of diversity than the bolitoglossines (16 Mexican and Guatemalan species of Sorex, Carraway, 2007; 30 species of Cryptotis, Moreno Cárdenas & Albuja, 2014), however, and appear to be more recent arrivals in Mesoamerica; Sorex probably arrived in southern Mexico and Guatemala in the late Miocene (Esteva et al, 2010). On an even more recent timescale, the rodent Ototylomys phyllotis arrived in Nuclear Central America around 3.4 Mya, prior to the Great American Biotic Interchange, from which it later spread (3.2-2.8 Mya).…”

American Recent Eulipotyphla: Nesophontids, Solenodons, Moles, and Shrews in the New World

“…Remarks: Subgenus Otisorex; Sorex veraepacis group. Kerr, 1792 FIGURES 4, 11, 24-27 Remarks: Type species of subgenus Otisorex; southern clade of the Sorex cinereus group (Hope et al, 2012); clade A2 of Esteva et al (2010). Molecular analyses of the Sorex cinereus group (Demboski and Hope et al, 2012) have provided intriguing insight into relationships among species and populations, including low genetic divergence among a number of recognized arctic species and the presence of unrecognized cryptic species.…”