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We synthesize observations from 1979 to 2016 of a contact zone involving two subspecies of pocket gophers (Thomomys bottae connectens and T. b. opulentus) and their respective chewing lice (Geomydoecus aurei and G. centralis) along the Río Grande Valley in New Mexico, U.S.A., to test predictions about the dynamics of the zone. Historically, the natural flood cycle of the Rio Grande prevented contact between the two subspecies of pocket gophers. Flood control measures completed in the 1930s permitted contact, thus establishing the hybrid zone between the pocket gophers and the contact zone between their lice (without hybridization). Since that time, the pocket gopher hybrid zone has stabilized, whereas the northern chewing louse species has replaced the southern louse species at a consistent rate of ~150 m/year. The 0.2–0.8 width of the replacement zone has remained constant, reflecting the constant rate of chewing louse species turnover on a single gopher and within a local pocket gopher population. In contrast, the full width of the replacement zone (northernmost G. centralis to southernmost G. aurei) has increased annually. By employing a variety of metrics of the species replacement zone, we are better able to understand the dynamics of interactions between and among the chewing lice and their pocket gopher hosts. This research provides an opportunity to observe active species replacement and resulting distributional shifts in a parasitic organism in its natural setting. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Mammalogy is the property of Oxford University Press / USA and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The pocket gopher Orthogeomys lanius (Elliot, 1905), unknown to science since the first 2 specimens were captured in 1904, is rediscovered in the mountains south and east of Pico de Orizaba in Veracruz, Mexico. Mitochondrial DNA extracted from the skin of the 109-year-old paratype specimen is nearly identical (0.3% cytochrome- b divergence) to that extracted from 2 newly captured specimens. Phylogenetic analyses of the complete cytochrome- b gene and 2 nuclear genes show O. lanius to be sister to the geographically widespread species O. hispidus. O. lanius has a diploid number of 44 and a fundamental number of 84, and the species is easily distinguished from O. hispidus by its larger size and dense, woolly pelage. Our observations suggest that O. lanius is reasonably abundant in a roughly 1,000-km2 region of central Veracruz, where it persists in forested refugia often too steep and rugged for cultivation by humans. La tuza Orthogeomys lanius (Elliot, 1905), desconocida para la ciencia desde que los 2 primeros ejemplares fueron capturados en 1904, se redescubrió en montañas del sur y este del Pico de Orizaba en Veracruz, México. El DNA mitocondrial extraído de la piel de el ejemplar paratipo de 109 años de antigüedad es casi idéntico (0.3% de divergencia en el gen citocromo b) al que se extrajo de 2 ejemplares capturados recientemente. El análisis filogenético del gen citocromo b completo y 2 genes nucleares mostró que O. lanius es la especie hermana de O. hispidus, especie ampliamente distribuída. O. lanius tiene un número cromosómico diploide de 44, un número fundamental de 84 y se distingue fácilmente de O. hispidus por su mayor tamaño y pelaje más largo y denso. Nuestras observaciones sugieren que O. lanius es relativamente abundante en un área de aproximadamente 1,000 km2 de la región central de Veracruz, donde persiste en refugios boscosos por lo regular muy inclinados y de superficie irregular para ser utilizados como campos agrícolas. [ABSTRACT FROM AUTHOR]

The southern pocket gopher, Thomomys umbrinus, currently contains 17 subspecies distributed from southeastern Arizona and southwestern New Mexico southward into the Trans-Mexico Volcanic Belt (TMVB) of central Mexico. Here we reevaluate relationships within this species, which, based on previous studies, is composed of 3 genetically divergent clades. Multilocus phylogenetic analyses uphold these clades (Northern Desert, Central Plateau, and TMVB) as well as the monophyly of T. umbrinus with respect to the 3 other species in the T. umbrinus complex ( T. atrovarius, T. nayarensis, and T. sheldoni). Reanalysis of published allozyme data shows a pattern of isolation by distance consistent with the hypothesis of gene flow among the 3 T. umbrinus clades. Species tree analyses of these clades reveal 4 divergent lineages (2 within the TMVB clade), which we recognize herein at the subspecies level. Cranial morphometrics show a moderate level of morphological separation among these clades in multivariate space. The present center of diversity of the T. umbrinus species group is in the southern Sierra Madre Occidental, which also appears to be the center of origin of the T. umbrinus complex. A synonymy of T. umbrinus is provided. La tuza sureña, Thomomys umbrinus, actualmente esta compuesta de 17 subespecies distribuidas desde el sureste de Arizona y suroeste de Nuevo México hacia el sur hasta el Cinturón Volcánico Trans-Mexicano (TMVB) en el centro de México. Aquí reevaluamos las relaciones dentro de esta especie, la cual, basados en estudios previos, esta compuesta de 3 clados genéticamente divergentes. Análisis filogenéticos multilocus sostienen estos 3 clados (Desierto del Norte, Altiplanicie Central, y TMVB), asi como la monofilia de T. umbrinus en relación con las otras 3 especies en el complejo T. umbrinus ( T. atrovarius, T. nayarensis, y T. sheldoni). El reanálisis de datos de alozimas publicados muestran un patrón de aislamiento por distancia, el cual es consistente con la hipótesis de flujo génico entre los 3 clados de T. umbrinus. Los análisis de árbol de especie de estos clados revelan 4 linajes divergentes (2 dentro del clado del TMVB), los cuales reconocemos aquí a nivel subespecie. La morfometría craneal muestra un nivel moderado de separación morfológica entre estos clados en el espacio multivariado. El centro actual de diversidad del grupo de especies de T. umbrinus es en el sur de la Sierra Madre Occidental, que también parece ser el centro de origen del complejo T. umbrinus. Una sinonimia para T. umbrinus se provee. [ABSTRACT FROM AUTHOR]

Copyright of Revista Mexicana de Biodiversidad is the property of Universidad Nacional Autonoma de Mexico, Instituto de Biologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The southern pocket gopher, Thomomys umbrinus, traditionally has been divided into as many as 5 genetically defined subclades based on chromosomal and allozymic data. Recent molecular analyses have resurrected 2 species from within these clades: 1 from the Pacific coastal lowlands (T. atrovarius), and another from the highlands of the Sierra Madre Occidental (T. sheldoni). In this study, multilocus genetic analyses of 3 mitochondrial and 5 nuclear genes reveal a previously unrecognized 3rd species apparently restricted to the Sierra del Nayar of northeastern Nayarit, Mexico. In addition to molecular and chromosomal studies of this new species, cranial morphology is analyzed to help distinguish it from its congeners. This taxon, T. nayarensis,i s described herein, and a key to distinguishing the 3 species of Thomomys in northeastern Nayarit is provided. [ABSTRACT FROM AUTHOR]

Thomomys sheldoni Bailey, 1915 is resurrected to recognize a genetically divergent clade of smooth-toothed pocket gophers that inhabits the high-elevation pine-oak forests of the Sierra Madre Occidental in Mexico from northwestern Chihuahua through Durango to western Zacatecas and northeastern Nayarit. Analyses of DNA sequences from 8 genes and genotype assignment tests for 21 allozyme loci establish this clade as a genetically isolated taxon within the T. umbrinus (sensu lato) complex. in addition to the T. sheldoni clade (diploid number of 2n = 76), 3 genetic clades within T. umbrinus (2n = 78) and 1 newly discovered clade (2n = 76) also were recovered in the phylogenetic analyses. individuals of T. sheldoni and T. umbrinus occur in close proximity with no evidence of gene flow and an average cytochrome-b genetic divergence of 15.6%. Analyses of cranial morphology reveal that skulls of T. sheldoni are, on average, broader and longer than skulls of T. umbrinus and T. atrovarius. We recognize and provide synonymies for 2 subspecies within T. sheldoni based on a weak genetic and morphological break that is coincident with a large, north-south gap in its distribution: T. s. sheldoni in the southern Sierra Madre Occidental, which includes specimens from the type locality and populations in Durango, Zacatecas, and Nayarit; and T. s. chihuahuae in the northern Sierra Madre Occidental, which is known only from Chihuahua. [ABSTRACT FROM AUTHOR]

Many species of pocket gophers and their ectoparasitic chewing lice have broadly congruent phylogenies, indicating a history of frequent codivergence. For a variety of reasons, phylogenies of codiverging hosts and parasites are expected to be less congruent for more recently diverged taxa. This study is the first of its scale in the pocket gopher and chewing louse system, with its focus entirely on comparisons among populations within a single species of host and 3 chewing louse species in the Geomydoecus bulleri species complex. We examined mitochondrial DNA from a total of 46 specimens of Geomydoecus lice collected from 11 populations of the pocket gopher host, Pappogeomys bulleri. We also examined nuclear DNA from a subset of these chewing lice. Louse phylogenies were compared with a published pocket gopher phylogeny. Contrary to expectations, we observed a statistically significant degree of parallel cladogenesis in these closely related hosts and their parasites. We also observed a higher rate of evolution in chewing louse lineages than in their corresponding pocket gopher hosts. In addition, we found that 1 louse species (Geomydoecus burti) may not be a valid species, that subspecies within G. bulleri are not reciprocally monophyletic, and that morphological and genetic evidence support recognition of a new species of louse, Geomydoecus pricei. [ABSTRACT FROM AUTHOR]

Thomomys atrovarius is redescribed to include the smooth-toothed pocket gophers that inhabit dry, thornscrub vegetation along the Pacific versant of the Sierra Madre Occidental of Mexico from northern Sinaloa into western Durango, northwestern Jalisco, and western Nayarit. Molecular analyses of mitochondrial and nuclear DNA sequences (including historical samples from museum skins) show high levels of genetic differentiation between T. atrovarius and T. umbrinus of the Sierra Madre Occidental (15.4% cytochrome-b divergence) and Mexican Central Plateau (16.9% divergence). Roughly coincident morphometric and genetic gaps divide T. atrovarius into 2 subspecies, T. a. parviceps in the north and T. a. atrovarius in the south, with probable intergradation in between. Most specimens of T. atrovarius, especially those of the southern subspecies, are distinguished easily from specimens of T. bottae and T. umbrinus on the basis of fur texture, and an analysis of cranial morphometrics shows little overlap between T. atrovarius and other Thomomys clades in Mexico. An analysis of niche parameters shows significantly different climate envelopes for T. atrovarius compared with other species of Thomomys, and a biogeographical review suggests that T. atrovarius has ancestral affinities to the south of its current distribution. A synonymy of T. atrovarius and a key to the currently recognized species of Thomomys in mainland Mexico are provided. [ABSTRACT FROM AUTHOR]

Abstract: Although molecular-based phylogenetic studies of hosts and parasites are increasingly common in the literature, no study to date has examined two congeneric lineages of parasites that live in sympatry on the same lineage of hosts. This study examines phylogenetic relationships among chewing lice (Phthiraptera: Trichodectidae) of the Geomydoecus coronadoi and Geomydoecus mexicanus species complexes and compares these to phylogenetic patterns in their hosts (pocket gophers of the rodent family Geomyidae). Sympatry of congeneric lice provides a natural experiment to test the hypothesis that closely related lineages of parasites will respond similarly to the same host. Sequence data from the mitochondrial COI and the nuclear EF-1α genes confirm that the two louse complexes are reciprocally monophyletic and that individual clades within each species complex parasitize a different species of pocket gopher. Phylogenetic comparisons reveal that both louse complexes show a significant pattern of cophylogeny with their hosts. Comparisons of rates of nucleotide substitution at 4-fold degenerate sites in the COI gene indicate that both groups of lice have significantly higher basal mutation rates than their hosts. The two groups of lice have similar basal rates of mutation, but lice of the G. coronadoi complex show significantly elevated rates of nucleotide substitution at all sites. These rate differences are hypothesized to result from population-level phenomena, such as effective population size, founder effects, and drift, that influence rates of nucleotide substitution. [Copyright &y& Elsevier]

Tests cospeciation in the Geomys-Geomydoecus assemblage by comparing protein differentiation in the pocket gophers to that of their chewing lice. Comparison of genetic-distance matrices; Inconsistencies; Distribution of Geomydoecus ewingi; Allozyme analysis; Tree estimation and comparison.

Examines DNA sequence variation in species of pocket gophers and their chewing lice for cospeciation. Rates of molecular evolution in the host-parasite assemblage; Overall rate of nucleotide substitution; Difference in synonymous substitution rate between lice and gophers.