Mammals In Mexico Research Articles

Helminth parasites of wild Mexican mammals: list of species, hosts and geographical distribution

In the present work, a total of 339 nominal taxa of helminths (53 trematodes, 46 cestodes, 12 acanthocephalans, 227 nem-atodes, and 1 hirudinean), associated with 136 taxa of wild mammals from Mexico, are listed. Information on hosts, hab-itat, distribution, and records is included; these data come from 242 localities, pertaining to 31 of the 32 Mexican states,and represent the current knowledge on helminth parasites of wild mammals in Mexico. Eighteen taxa of helminths are registered for the first time in Mexico, and 46 new locality records are presented.

DNA Barcoding of Mammals in Mexico: Implications for Biodiversity

The Mexican Barcode of Life (MEXBOL) project started as an initiative by researchers who wanted Mexico to join the international DNA barcoding (iBOL) collaboration to establish a genetic system of species identification and discovery. MEXBOL has three main nodes associated with different research institutions in the northern, central, and southern parts of the country. At the beginning of 2009, the laboratories of the three nodes began to operate with support from the University of Guelph in Canada where DNA barcoding began in 2003. By the end of 2011, the laboratories in Mexico will be completely equipped and fully operational. The project is funded by the Consejo Nacional de Ciencia y Tecnologia (CONACyT). In addition, the steering committee of MEXBOL supports the Comision Nacional para el Conocimiento y Uso de la Biodiversidad (CONABIO) initiative to offer grants to any university and research center for barcoding collections of Mexican specimens. We present preliminary results of projects dealing with barcoding Mexican mammals. The aims of these analyses are to evaluate the importance of the DNA barcoding (using cytochrome c oxidase subunit I gene; COI) for the identification of species, study of genetic diversity, and taxonomic review. Our preliminary data suggest that DNA barcodes can be used for the discovery of cryptic species and have important implications to the understanding of the mega-diversity of mammals in Mexico.

Serological evidence of Toxoplasma gondii infection in captive marine mammals in Mexico

Toxoplasma gondii infection in marine mammals is important because they are considered as a sentinel for contamination of seas with T. gondii oocysts, and toxoplasmosis causes mortality in these animals, particularly sea otters. Serological evidence of T. gondii infection was determined in 75 captive marine mammals from four facilities in southern and central geographical regions in Mexico using the modified agglutination test (MAT). Antibodies (MAT, 1:25 or higher) to T. gondii were found in 55 (87.3%) of 63 Atlantic bottlenose dolphins (Tursiops truncatus truncatus), 3 of 3 Pacific bottlenose dolphins (Tursiops truncatus gillii), 2 of 4 California sea lions (Zalophus californianus), but not in 3 West Indian manatees (Trichechus manatus), and 2 Patagonian sea lions (Otaria flavescens). Seropositive marine mammals were found in all 4 (100%) facilities sampled. All marine mammals were healthy and there has not been any case of clinical toxoplasmosis in the facilities sampled for at least the last 15 years. The seroprevalence of T. gondii infection in marine mammals of the same species did not vary significantly with respect to sex and age. This is the first report on the detection of antibodies to T. gondii in marine mammals in Mexico.

Dispersal limitation and geographical distributions of mammal species

AbstractAim To relate the dispersal limitation of endemic terrestrial mammals in Mexico to species life‐history traits and latitude.Location Mexico.Methods We modelled species ecological niches projected as potential distributions (P) using point occurrence data and 19 environmental variables for 89 endemic mammal species, and compared the areas covered by these ecological niche models with maps of species actual distributions (R) based on minimum convex polygons connecting marginal records based on museum specimens. We correlated body mass, food habits (herbivore, omnivore, insectivore, frugivore/granivore), volant and non‐volant (fossorial, arboreal, terrestrial) habits and mean latitude to the proportion of occupancy of species potential distributional areas (R/P).Results R and P were significantly positively correlated, with an overall average R/P ratio of 0.49. Less than half of the endemics (41 species) had a high occupancy (R/P values ranging from 0.50 to 0.90); a few (four species) showed full occupancy (> 0.90). Body mass and food habits were not correlated with R/P, but latitude showed significant correlations with R/P; volant mammals tended to show higher R/P values than non‐volant mammals.Main conclusions Few species filled most of the spatial extent of their ecological niches. Life‐history traits were generally poor predictors of proportional occupancy of species potential distributions. Endemics occurring at higher latitudes showed higher occupancy, suggesting that abiotic factors are likely to limit their distributions. Conversely, species at lower latitudes showed lower occupancy, suggesting that their distributions are limited by biotic factors and/or by geographical or historical barriers that prevent dispersal. The dispersal abilities of volant compared with non‐volant endemics can explain the higher occupancy in species potential distributions in the former group. These trends provide a baseline for exploring the importance of life‐history traits and abiotic versus biotic factors in limiting species distributions.

Deforestation affects biogeographical regionalization: a case study contrasting potential and extant distributions of Mexican terrestrial mammals

We used ecological niche modelling projected as species' potential (based on the original vegetation map) and extant (based on the 2000 land use and vegetation map) distributions to analyse changes on patterns of endemism of terrestrial mammals occurring in Mexico. Based on the biogeographic method of Parsimony Analysis of Endemicity, we obtained cladograms under scenarios of species' potential distribution (t1) and extant distributions (t2). We found that the resolution of consensus cladogram in t2 was poorer, while there were more geographic synapomorphies in t1, and more autapomorphies in t2 due to a reduction of species' distributions as a consequence of deforestation. We defined a hierarchical regionalization with two regions with the cladogram of t1; a transitional zone, two subregions, five dominions, and 15 provinces. Conversely, the consensus cladogram of t2 had a basal trichotomy, and the position of the Sierra Madre Occidental changed compared with t1. In t1 and t2, the Yucatán Peninsula+Chiapas+Isthmus of Tehuantepec clade was maintained, although in t2 it was separated from the remaining areas of the country. The impact of deforestation on species distributions strongly affected the biogeographic regionalization of terrestrial mammals in Mexico.

CONSERVATION PRIORITIES FOR MAMMALS IN MEGADIVERSE MEXICO: THE EFFICIENCY OF RESERVE NETWORKS

A major goal of conservation biologists is to identify critical areas for the conservation of biological diversity and then strategically include them in an efficient system of reserves. In general, however, reserve networks have been selected for different objectives, and most countries lack an evaluation of their reserves' ability to represent a percentage of the national diversity. This paper evaluates the effectiveness of a network of reserves to represent the species of mammals in Mexico. The focus of the analyses is on species and site level, evaluating the representation of all terrestrial mammals in the 30 most important reserves. The representation of all species, endemic species, endangered species, and species with restricted distributions in the reserves was assessed and compared. Endemic or endangered species with restricted distributions were expected to be less represented in reserves than were widespread species. The most important reserves for the conservation of mammals were determined with the use of complementarity analyses. Priority sites for the representation of all the species currently absent from the reserve network were then selected. The results have broad applications for conservation. First, 82% of the mammal species from Mexico were represented in the reserve network, which covers a small portion (3.8%) of the country. Second, this percentage is certainly larger as several reserves were not evaluated due to a lack of data. A priority for a national conservation strategy could be to conduct biological surveys in those reserves lacking inventories to evaluate their contribution to conservation. Third, in spite of its demonstrated value, Mexico's reserve network can be improved by designating complementary areas. Additional priority sites, where reserves are required to represent most gap species in the network, were identified. Finally, it is clear that this reserve network has limitations for maintaining biodiversity and ecosystem services at regional scales. A comprehensive conservation strategy has, therefore, to incorporate mechanisms that enhance the value of human-dominated landscapes for the maintenance of biodiversity.

The cost of postponing biodiversity conservation in Mexico

Though Neotropical countries are the most species rich in the world, their biodiversity is threatened by the loss of native vegetation. Land conversion in Mexico during the last 30 years has been extensive and is representative of that of other developing countries. However, the effects of land use change on the required size and configuration of an adequate biological conservation area network are largely unknown. It is shown here that endemic mammals in Mexico could have been protected considerably more economically if a conservation plan had been implemented in 1970 than is possible today due to extensive conversion of primary habitats. Analysis of the distributions of 86 endemic mammal species in 1970, 1976, 1993, and 2000 indicates that the distributions of 90% of the species shrank during this 30-year period. At each time step, optimal conservation area networks were selected to represent all species. 90% more land must be protected after 2000 to protect adequate mammal habitat than would have been required in 1970. In addition, under a realistic conservation budget, 79% fewer species can be represented adequately in a conservation area network after 2000 compared to 1970. This provides an incentive for rapid conservation action in Mexico and other biodiversity hotspots with comparable deforestation rates, including Burma, Ecuador, Indonesia, the Philippines, and Sri Lanka. Due to ongoing habitat degradation, the efficiency of a conservation plan decreases with delays in its implementation.

Nested areas of endemism analysis

AbstractAim To develop and evaluate a nested clade approach to aid in the determination of areas of endemism (AoE) in biogeographical studies.Methods We adapted the nested clade analysis (NCA) to studies of areas of endemism. For this purpose we adapted several of the programs currently in use. Two data sets were examined using this approach – one involvingSciobiusin southern Africa and the other involving terrestrial mammals in Mexico.Results Nested clade analysis as applied to areas of endemism produced results similar to those of previous analyses ofSciobusin southern Africa. An analysis of terrestrial mammals in Mexico supports the designation of some biogeographical provinces as areas of endemism while suggesting that other provinces may comprise composite distributions that should be subdivided.Main conclusions The nested clade analysis approach utilized primarily in genetic analysis of phylogeographical patterns in population biology studies can be adapted to understanding AoE in the realm of biogeography. This approach offers a statistical paradigm to evaluate AoE suggested by parsimony analysis of endemicity (PAE) trees.

People and mammals in Mexico: conservation conflicts at a national scale

Contrary to much supposition, recent studies, typically at global and continent-wide scales, have documented a positive relationship between spatial variations in human density and species richness of selected groups of vertebrates. How widely this pattern generalises remains unknown, and particularly how well it extends to analyses at the extent of a country and at reasonably fine spatial resolution, and to regions with well-developed mechanised agricultural infrastructure. Here, we demonstrate that there is a positive relationship between human density and mammal species richness across Mexico, and that this appears to follow from similar patterns between spatial environmental variation (particularly net primary productivity, precipitation and temperature) and both human density and mammal species richness. These results have some potentially important implications for conservation planning in the region, particularly given that optimal complementary sets of areas to represent all mammal species in Mexico tend to lie in areas of disproportionately high human density.

Mites and ticks associated with some small mammals in mexico

This paper reports mites and ticks of small mammals in the states of Baja California Sur, Chiapas, Jalisco, Michoacán, Oaxaca, Puebla, San Luis Potosí and Veracruz in México. Genera of small mammals sampled were: Balantiopteris, Chaetodipus, Cryptotis, Habromys, Heteromys, Liomys, Marmosa, Megadontomys, Microtus, Nyctomys, Oryzomys, Osgoodomys, Peromyscus, Reithrodontomys, Sigmodon and Sorex. The recorded mites belonged to 15 families but Glycyphagidae, Laelapidae, Listrophoridae and Trombiculidae included most species.

105 años de investigación mastozoológica en México (1890-1995): Una revisión de sus enfoques y tendencias

Se revisaron y analizaron las publicaciones (artículos de revistas científicas, la serie Mammalian Species, capítulos de libros y libros) sobre investigaciones de los mamíferos de México publicados entre 1890 y 1995. Los trabajos de investigación se agruparon dentro de 11 temas generales con subdivisiones más específicas y fueron organizados en una base de datos. Se registraron un total de 2129 referencias, de los cuales 1826 son artículos en publicaciones periódicas, 206 fascículos monográficos dentro de la serie Mammalian Species, 40 capítulos de libro y 45 libros. El número de artículos publicados en revistas periódicas mostró un incremento notable a partir de la década de los 1950’s, debido al reclutamiento de un mayor número de científicos e instituciones con interés profesional en la Mastozoología. El estado de Veracruz ha sido el más estudiado, con un 22% del total de trabajos y, el de Tlaxcala el menos estudiado, con apenas el 1% del total de trabajos. El 79% de los trabajos fueron de autores extranjeros, en tanto, se publicaron el 82% en revistas extranjeras, sobresaliendo el Journal of Mammalogy, con el 21% de las publicaciones. El 40% de los trabajos se refirieron a taxonomía y filogenia y el 36% a la distribución geográfica de las especies. En las restantes categorías, los autores extranjeros publicaron más que los mexicanos, excepto en los capítulos de libros, los cuales a su vez, han sido editados en mayor cantidad por editoriales extranjeras. Sin embargo, los libros han sido editados con más frecuencia en México. Esta tendencia demuestra que los investigadores extranjeros (particularmente estadounidenses) y, recientemente los nacionales, han jugado un papel preponderante en el estudio de los mamíferos de México. Se propone la necesidad de establecer un proyecto nacional que promueva e impulse los estudios enfocados a las disciplinas históricamente poco abordadas, además de las comúnmente tratadas, para garantizar un conocimiento adecuado de las mastofauna nacional.

Geographic Patterns of Body-Mass Diversity in Mexican Mammals

At the geographic scale, body mass has been analysed as a correlate of local abundance and area of range, or in terms of latitudinal variations in body mass, both intra- and interspecifically. One productive approach has been the analysis of the frequency distribution of body mass in animal assemblages at different spatial scales. In this paper we use such an approach to describe the geographic patterns of body-mass diversity in the Mexican mammalian fauna. We found contrasting patterns for bats and non-volant species: Non-volant mammals in Mexico followed the already described pattern of a right-skewed distribution of body size at large scales and a more even distribution at smaller scales; bats, in contrast, showed skewed distributions at all scales. Statistical tests based on null models demonstrated that most assemblages of non-volant mammals present higher diversity of body mass than expected by chance, whereas chiropteran assemblages show the variation in body size that would be expected from randomly sampling the whole fauna of the country. Although we found an effect of latitude on body-mass diversity, we also demonstrated that topographic features (peninsulas and mountain ranges) have a strong influence on the patterns of body mass at small scales. Using SHE analysis, a method to decompose the elements of diversity, we studied the scaling of body-mass diversity in south-eastern Mexico and documented subtle patterns that had not been observed in comparisons between biomes and local communities. In particular, we found that at intermediate scales the evenness of the distribution of body mass values remains constant, so diversity is determined chiefly by changes in the number of size classes found in the assemblages. In contrast, at the national level, diversity is comparatively low, despite the presence of all size classes, because of the low evenness, reflected in the highly skewed frequency distribution of body-mass values. Our results show that the body-mass structure of mammalian assemblages is determined by a complex interplay of local and regional processes that act at different spatial and temporal scales.