Variation and secondary sexual dimorphism of skeletal characters in Glossophaga morenoi and G. leachii from southwestern México (Chiroptera: Phyllostomidae)

Morphometric variation and secondary sexual dimorphism were evaluated and compared in 9 cranial and 23 postcranial characters of Glossophaga leachii and G. morenoi. Analysis of coefficients of variation (CV) showed that the degree of variation as well as its pattern are very similar for both species, with their CVs being lower than those found in birds and other mammals. Sexual dimorphism was tested using ANOVA and MANOVA. Results were significant for three cranial and three postcranial characters of G. leachii, as well as for nine postcranial traits of G. morenoi. Results of MANOVA on the same characters confirmed univariate results. Females are larger than males in most variables for both species, presumably as a result of higher energetic and physical demands of pregnant females and nursing mothers. Importance values in discriminating between sexes were calculated for each variable, importance profiles constructed, and significance of their correlations tested for cranial and postcranial characters separately to reassess the hypothesis that once differentiation occurs at the specific level, sexual dimorphism is no longer constrained in the same fashion as in the ancestral condition. Our results suggest that for cranial characters that is the case. For postcranial elements, however, importance profiles are highly correlated, suggesting that for characters with presumably higher fitness value, ancestral constraints remain after speciation has occurred.