Martha M. Zarco-González

Cougar and jaguar habitat use and activity patterns in central Mexico

In this study the habitat use and activity patterns of the two of the largest cats of the Americas in central Mexico were studied. Three ways to detect felid presence were employed from August 2002 to May 2006: interviews, signs, and camera-traps. 478 records were obtained, from which 441 were from cougar and 37 from jaguar. These records included positive response in 118 of 140 interviews and 236 records of signs (mainly tracks and scats), and 124 photographs. Both felids preferred pine-oak forest habitats, with altitudes higher than 1800 m, distances between 3509 and 4377 m from roads, between 2329 and 4650 m from settlements, and distances to very steep slopes between 1048 and 2059 m, for jaguar, and for cougar lower than 1047 m. Jaguar activity was recorded mainly during nighttimes, between 0:00 and 6:00, whereas cougar was active between 4:00 and 6:00 and between 18:00 and 22:00 hours, avoiding the jaguars principal activity period.

Variation of abundance and density of Puma concolor in zones of high and low concentration of camera traps in Central Mexico

Little is known about the status of Puma concolor populations in Central and South America. Due to this reason, the present study contributes to the knowledge on puma populations providing information on abundance and density in Sierra Nanchititla, Mexico, as well as comparing recorded values against those obtained from zones of high and low concentration of camera traps. The sampling was carried out during a period of 30 months, which were divided into 3-month independent blocks. For the 8 first blocks, ten camera traps were set in an area where the separation among cameras was 1.6 km, and in the 2 last blocks 17 camera traps were set in an area where the separation was 4.6 km. The abundance was estimated between 2 and 5 individuals for the area with the highest concentration of cameras, lower than the abundance obtained in the area with the lowest concentration of cameras, i.e., 6 individuals. The density of the area with the highest camera concentration had a variation between 2.74 and 6.86 individuals/100 km2 in an effective survey area of 72.8 km2 and for the area of lowest concentration it was 1.21 individual/100 km2 in an effective survey area of 492.6 km2.

Genetic diversity and genetic structure of an endemic Mexican Dusky Rattlesnake (Crotalus triseriatus) in a highly modified agricultural landscape: implications for conservation

Abstract It is necessary to determine genetic diversity of fragmented populations in highly modified landscapes to understand how populations respond to land-use change. This information will help guide future conservation and management strategies. We conducted a population genetic study on an endemic Mexican Dusky Rattlesnake (Crotalus triseriatus) in a highly modified landscape near the Toluca metropolitan area, in order to provide crucial information for the conservation of this species. There was medium levels of genetic diversity, with a few alleles and genotypes. We identified three genetically differentiated clusters, likely as a result of different habitat cover type. We also found evidence of an ancestral genetic bottleneck and medium values of effective population size. Inbreeding coefficients were low and there was a moderate gene flow. Our results can be used as a basis for future research and C. triseriatus conservation efforts, particularly considering that the Trans-Mexican Volcanic Belt is heavily impacted by destructive land-use practices.

Microhabitat Types Promote the Genetic Structure of a Micro-Endemic and Critically Endangered Mole Salamander (Ambystoma leorae) of Central Mexico

The reduced immigration and emigration rates resulting from the lack of landscape connectivity of patches and the hospitality of the intervening matrix could favor the loss of alleles through genetic drift and an increased chance of inbreeding. In order for isolated populations to maintain sufficient levels of genetic diversity and adapt to environmental changes, one important conservation goal must be to preserve or reestablish connectivity among patches in a fragmented landscape. We studied the last known population of Ambystoma leorae, an endemic and critically threatened species. The aims of this study were: (1) to assess the demographic parameters of A. leorae and to distinguish and characterize the microhabitats in the river, (2) to determine the number of existing genetic groups or demes of A. leorae and to describe possible relationships between microhabitats types and demes, (3) to determine gene flow between demes, and (4) to search for geographic locations of genetic discontinuities that limit gene flow between demes. We found three types of microhabitats and three genetically differentiated subpopulations with a significant level of genetic structure. In addition, we found slight genetic barriers. Our results suggest that mole salamander’s species are very sensitive to microhabitat features and relatively narrow obstacles in their path. The estimates of bidirectional gene flow are consistent with the pattern of a stepping stone model between demes, where migration occurs between adjacent demes, but there is low gene flow between distant demes. We can also conclude that there is a positive correlation between microhabitats and genetic structure in this population.

Genetic structure and diversity in an isolated population of an endemic mole salamander (Ambystoma rivulare Taylor, 1940) of central Mexico

Human activities are affecting the distribution of species worldwide by causing fragmentation and isolation of populations. Isolation and fragmentation lead to populations with lower genetic variability and an increased chance of inbreeding and genetic drift, which results in a loss of biological fitness over time. Studies of the genetic structure of small and isolated populations are critically important for management and conservation decisions. Ambystoma rivulare is a micro-endemic Mexican mole salamander from central Mexico. It is found in the most ecologically disturbed region in Mexico, the Trans-Mexican Volcanic Belt. The goal of this study of the population genetics of the micro-endemic mole salamander was to provide information to be used as a basis for future research and conservation planning of this species and other species of the Ambystoma genus in Mexico. The structural analysis found two subpopulations, one for each river sampled, with no signs of admixture and very high levels of genetic differentiation. Medium to high levels of heterozygosity and few alleles and genotypes were observed. Evidence of an ancestral genetic bottleneck, low values of effective population size, small inbreeding coefficients, and low gene flow were also found.

Genetic variability and structure of an isolated population of Ambystoma altamirani, a mole salamander that lives in the mountains of one of the largest urban areas in the world

Amphibians are globally threatened by habitat loss and fragmentation; species within the order Ambystoma are not the exception, as there are 18 species of mole salamanders in México, of which 16 are endemic and all species are under some national or international status of protection. The mole salamander, Ambystoma altamirani is a microendemic species, which is distributed in central México, within the trans-Mexican volcanic belt, and is one of the most threatened species due to habitat destruction and the introduction of exotic species. Nine microsatellite markers were used to determine the genetic structure, genetic variability, effective population size, presence of bottlenecks and inbreeding coefficient of one population of A. altamirani to generate information which might help to protect and conserve this threatened species. We found two genetic subpopulations with significant level of genetic structure (

Nesting ecology of the American crocodile in La Encrucijada Biosphere Reserve, Mexico

F_{\mathrm{ST}}= 0.005

Uso tradicional de vertebrados silvestres en la Sierra Nanchititla, México

FST=0.005) and high levels of genetic variability (