Resumen:
The demographic characteristics of an amphibian population fluctuate independently over time, mainly in response to the temporal variation of environmental factors, especially precipitation and temperature. These temporal fluctuations may contribute to the size of an amphibian population and could be used to determine the current conservation status of a species. During a five year (2004–2008) period, we studied the relative abundance, sex ratio, and age-sex structure of a population of metamorphosed individuals of the endemic treefrog Hyla eximia in CentralMexico. We also studied the species’ relationship with climatic variables such as temperature and precipitation.We found an interannual constant abundance during the study period. However, interannual differences were observed in the population structure by age-sex category (males, females, or juveniles), with decreased abundance of males and juveniles during the rainy months (August–November). The annual abundance of H. eximia was positively correlated with rainfall, but negatively with monthly temperature.We found the sex ratio was male-biased (2:1), except for year 2008. Also, differences in snout-vent length (SVL) were found between years, suggesting changes in recruitment of new individuals.We conclude that variations in abundance, and frequencies by age-sex category, of H. eximia are related to seasonal variations in temperature and precipitation characteristics of temperate zones. However, this temporal stability may suggest that anurans have an unusual capacity to persist even in the face of human-induced habitat change.
Descripción:
Changes in abundance and distribution of the three H. eximia age-sex categories, are related to seasonal variations in temperature and precipitation during the year. The ability of H. eximia to persist is constrained by human-induced habitat alterations of the temperate forest habitat in the CentralMexican Plateau. Small frog species, such as H. eximia, may be strongly disadvantaged by habitat fragmentation. The CentralMexican Plateau contains a major metropolitan area and 44.7% of this area is used for agriculture (CONAPO, 2010). This presents the possibility of a reduction in the suitability of existing habitat patches (i.e., fragments) which may affect both local and landscape-level pond-breeding amphibian population dynamics. Only temperate forest habitat seems to be suitable for H. eximia, therefore, conservation efforts should be directed to areas where suitable ecological variables are present and especially where human encroachment affects tree microhabitat. Most of what we know about this endemic treefrog comes from occasional captures of active animals. New studies are needed to better understand how the stability of a population of frogs relates to areas that are degraded by human land-use. For example, mark–recapture studies can elucidate terrestrial habitat requirements for local populations, genetic approaches may be used to infer gene flow, and to estimate dispersal and immigration. These types of studies will provide crucial information about the relative impact of land use on effective population size and reproductive success of local populations
Excepto si se señala otra cosa, la licencia del ítem se describe cómo openAccess