Untitled

Abstract

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 effective size of an amphibian population and could be used to inform the current conservation status of a species. During a five year (2004)(2005)(2006)(2007)(2008) period, we studied the relative abundance, sex ratio, and size-age structure of a population of metamorphosed individuals of the endemic treefrog Hyla eximia in Central Mexico. We also studied the species' relationship with climatic variables such as temperatura 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 increased abundance of juveniles during the rainy months (AugustNovember). 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 Temporal stability of an endemic Mexican treefrog2 The demographic characteristics of an amphibian population fluctuate independently over time, 3 mainly in response to the temporal variation of environmental factors, especially precipitation 4 and temperature. These temporal fluctuations may contribute to the effective size of an 5 amphibian population and could be used to inform the current conservation status of a species. 6 During a five year (2004)(2005)(2006)(2007)(2008) period, we studied the relative abundance, sex ratio, and size-age 7 structure of a population of metamorphosed individuals of the endemic treefrog Hyla eximia in 8 Central Mexico. We also studied the species' relationship with climatic variables such as 9 temperature and precipitation. We found an interannual constant abundance during the study 10 period. However, interannual differences were observed in the population structure by age-sex 11 category (males, females, or juveniles), with increased abundance of juveniles during the rainy 12 months (August-November). The annual abundance of H. eximia was positively correlated with 13 rainfall, but negatively with monthly temperature. We found the sex ratio was male-biased (2:1) 14 except for year 2008. Also, differences in snout-vent length (SVL) were found between years, 15 suggesting changes in recruitment of new individuals. We conclude that variations in abundance, 16 and frequencies by age-sex category, of H. eximia are related...