Diego F. García-Mendoza

Bats of Northwestern Durango, Mexico: Species Richness at the Interface of Two Biogeographic Regions

Abstract An updated list of the bats of northwestern Durango, based on recent collections and literature records, is presented. A total of 43 species were recorded, five for the first time in the state (Balantiopteryx plicata, Artibeus hirsutus, Artibeus intermedius, Chiroderma salvini, and Myotis carteri). Comparisons with other intensively sampled localities across Mexico indicate that species richness in the Sierra Madre Occidental of northwestern Durango is comparable to that of Mexican rainforests, resulting from high diversity of habitats in relatively small areas. Species composition in this region is dominated by vespertilionid and molossid bats, whereas phyllostomids dominate tropical rainforests; thus, species assemblages are considerably different. Moreover, anthropogenic pressure is comparatively lower than in most of the humid tropics of Mexico. Nonetheless, no protected area exists that includes the complete spectrum of habitats of the region. An immediate conservation strategy is urgently needed if this largely unknown region of Mexico is to be preserved.

A checklist of the mammals (Mammalia) of Chihuahua, Mexico

An updated list of the mammals of Chihuahua state, Mexico was assembled from the literature and from museum specimens. We documented 133 species (15 endemic to Mexico and 11 new for Chihuahua), representing 25 families, 75 genera, and 27.4% of the Mexican terrestrial mammalian fauna. Four species are probably extirpated from the state. Four major ecoregions have been defined for Chihuahua: Arid, Valleys, Sierra, and Quebradas. Species richness was the highest in Valleys, and consisted mostly of species with Nearctic affinities. In contrast, Quebradas were the least species-rich, but included mostly Neotropical species that occur only in this ecoregion of Chihuahua. Despite the fact that Chihuahua harbors considerable biodiversity and unique Mexican biomes, conservation efforts are insufficient. The current rate of anthropogenic modification in the state requires a comprehensive strategy if Chihuahua’s biodiversity is to be preserved.

Morphologic characterization of Peromyscus schmidlyi (Rodentia: Cricetidae), an endemic of the Sierra Madre Occidental, Mexico

Abstract Based on examination of 705 museum specimens, including the holotype and individuals identified using molecular attributes, we characterized Schmidlys deer mouse (Peromyscus schmidlyi) using a set of morphometric and morphological characteristics. Discriminant function analysis was performed on 14 cranial attributes to find those most useful to separate species. Factorial analysis of variance and multivariate analysis of variance were used to test for significant differences due to species, sex, age, and geographic location. We compared and contrasted P. schmidlyi with P. boylii rowleyi and P. spicilegus, morphologically similar and partially sympatric species, and reevaluated the distribution of the 3 species in the Sierra Madre Occidental (SMO) of Mexico. P. schmidlyi is a medium-sized Peromyscus distinguishable by a set of characters including overall size intermediate between P. spicilegus and P. boylii rowleyi, relatively wider braincase and zygoma, hourglass-shaped interorbital constriction, large auditory bullae, and strongly bicolored, tufted tail. Morphometric characterization is possible only when age and geographic location are taken into consideration. Several specimens previously identified as P. boylii rowleyi were reidentified as P. schmidlyi. Records available showed that P. schmidlyi is distributed in forested highlands of the SMO, from northern Chihuahua to northern Jalisco, between 1,550 (on the western versant) and 3,000 m of elevation. The species is sympatric with P. boylii rowleyi between 2,100 and 2,400 m along the eastern versant of the SMO and with P. spicilegus along a narrower band (1,550–2,000 m) on the steeper western slope. Distribution of these species closely reflects the most recent ecological regionalization of the SMO. Resumen Se examinaron 705 ejemplares de museo incluyendo el holotipo e individuos identificados usando citocromo-b mitocondrial, para caracterizar Peromyscus schmidlyi desde el punto de vista morfológico y morfométrico. Se midieron 14 variables craneales y se realizó un análisis de funciones discriminantes para encontrar aquellas más útiles para separar especies. Se utilizaron análisis de varianza univariados (ANOVA) y multivariados (MANOVA) factoriales para evaluar diferencias entre especies, sexos y distribución geográfica. P. schmidlyi se comparó con P. boylii rowleyi y P. spicilegus, especies morfológicamente similares y parcialmente simpátricas con P. schmidlyi. Finalmente, se reevaluó la distribución de las 3 especies en la Sierra Madre Occidental (SMO). P. schmidlyi es de tamaño mediano, distinguible por un conjunto de caracteres incluyendo: tamaño general intermedio entre P. spicilegus y P. boylii rowleyi, caja craneana y arco cigomático relativamente anchos, región interorbital en forma de reloj de arena, bulas auditivas grandes, y cola marcadamente bicolor con un pincel en la punta. La caracterización morfológica de P. schmidlyi requiere tomar en cuenta la edad relativa y localidad de los ejemplares. Individuos previamente identificados como P. boylii rowleyi fueron reidentificados como P. schmidlyi. Como resultado, se puede concluir que P. schmidlyi se distribuye en los bosques de coníferas y pino–encino de la SMO, del norte de Chihuahua al norte de Jalisco, entre 1,550 (en la vertiente occidental) y 3,000 m sobre el nivel del mar. Es simpátrica con P. boylii rowleyi entre 2,100 y 2,400 m a lo largo de la vertiente oriental, y con P. spicilegus sobre una angosta banda (1,550–2,000 m) en la abrupta cara occidental. La distribución de estas especies sigue muy de cerca la ecoregionalización más reciente de la SMO.

A checklist of the mammals (Mammalia) from Durango, western Mexico

An updated list of the mammals of Durango state, Mexico was built from literature records and Museum specimens. A total of 139 species have been recorded, representing 28.3 % of the Mexican terrestrial mammals, and 25.1 % species more compared to the previous account. Two species have been extirpated from the state, 23 are endemic to Mexico. Four major ecoregions have been previously defined for the state, Arid, Valleys, Sierra, and Quebradas. Species richness is highest at the Quebradas, a tropical ecorregion, whereas the aridlands are the least species-rich. The Sierra has the highest number of endemic species (11) followed by Quebradas (7), Valleys and Arid (3). Despite the fact that Durango harbors one of the largest diversities of mammals of the country, conservation efforts are minimal, and the current protected areas do not include the most species-rich regions. The current rate of anthropogenic modification in the state makes urgent to put in practice already existing plans to protect Durango’s unique biodiversity.

Phylogeography of Peromyscus schmidlyi: an endemic of the Sierra Madre Occidental, Mexico

Abstract Peromyscus schmidlyi is an endemic rodent from the forested highlands of the Sierra Madre Occidental (SMO) in Mexico. Using 2 genetic markers (cytochrome-b and D-loop) we explored the possible relationship between a recently proposed division of pine–oak forests of the SMO into specific regional communities and patterns of genetic and morphometric variation in P. schmidlyi. We found no genetic structure or significant relationships between either marker and ecological or morphometric variation. Phylogenetic and haplotypic network analyses revealed no geographically structured clusters; phylogenetic trees were shallow and networks were star-shaped. No signal of selection was detected for either marker at the local level. All available evidence suggests that the current distribution of P. schmidlyi is the result of dispersal into the SMO followed by rapid population expansion throughout the area in the late Pleistocene, following the glacial cooling of the SMO highlands. Resumen Peromyscus schmidlyi es un roedor endémico de los bosques de pino–encino de las partes altas de La Sierra Madre Occidental (SMO), México. Utilizando dos marcadores moleculares (Citocromo B y D-loop), se evaluaron las posibles relaciones entre la variación genética y morfométrica de las poblaciones de P. schmidlyi y la recientemente propuesta regionalización de las comunidades vegetales de las partes altas de la sierra. No encontramos estructura genética, ni relaciones significativas entre la variación genética de ningún marcador y la variación ecológica o morfométrica. El análisis de filogenias y redes haplotípicas no reveló grupos significativos geográficamente estructurados, más bien, lo que se obtuvo fueron árboles con poca profundidad y redes en forma de estrella. Asimismo, las pruebas de neutralidad por localidad fueron no significativas y no se encontró evidencia de selección en ninguno de los marcadores. La evidencia disponible sugiere que la distribución actual de P. schmidlyi es resultado de dispersión seguida de una rápida explosión de la población sobre las partes altas de la SMO a finales del Pleistoceno, como resultado del enfriamiento glacial de las mismas.

Mammals of the San Pedro-Mezquital River Basin, Durango-Nayarit, Mexico

The San Pedro–Mezquital River Basin is located in the southern Sierra Madre Occidental, at the Nearctic– Neotropical transition. The river traverses the Sierra through a canyon that reaches over 1000 m in depth. Based on examination of museum specimens, literature records, and our own collections, we documented the occurrence of 120 species (24.6% of the Mexican terrestrial mammals), 24 endemic to Mexico. Richness was comparable with other megadiverse areas of Mexico, and higher than any other Nearctic–Neotropical transition area, moreover species richness is likely to rise as survey continues. Contrary to expectation, distribution of mammals across the basin not only reflected the Nearctic–Neotropical divide, but a third fauna that is a mixture of tropical, temperate and desert species was identifiable at the canyon. Anthropogenic threats including damming of the river, uncontrolled cattle grazing, and pollution from domestic sources, call for effective management strategies to preserve one of the most biodiverse areas of Mexico.

Geographic cranial variation in Peromyscus melanotis (Rodentia: Cricetidae) is related to primary productivity

The black-eared mouse Peromyscus melanotis is distributed in conifer forests and highland prairies throughout the Trans-Mexican Volcanic Belt, Eastern Sierra Madre and Western Sierra Madre in Mexico, and isolated mountain ranges in Arizona, United States. We examined geographic variation in cranial measurements throughout the distribution of the species in Mexico. Because populations of these major ranges are isolated, we expected discontinuities in variation consistent with geographic gaps. Instead, we found no differences between the Sierras and significant differences between them and the Trans-Mexican Volcanic Belt. Moreover, a north-to-south trend of size increase was detected. By relating size to 6 environmental variables, we evaluated 4 hypotheses previously proposed to explain the observed pattern of variation: 1) seasonality, 2) body heat conservation or Bergmanns rule, 3) primary productivity, and 4) body heat dispersion. Significant positive correlations with elevation, productivity, and humidity, and negative correlations with annual mean temperature, temperature seasonality, and latitude led us to conclude that the observed pattern of variation in size is not related to body heat conservation or loss, but driven by primary productivity, a positive correlate of resource availability.