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bioRxiv · 10.1101/2024.11.19.624291

Body Size Variation And Sexual Dimorphism In Eleven Species Of Venezuelan Anurans

Canizales, I.
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Abstract

This study investigates intra- and interspecific variation in snout-vent length (SVL) and abdominal width (AW) across 11 anuran species in Venezuela, revealing significant patterns of sexual size dimorphism (SSD) in seven species. Females exhibited larger SVL than males in most species (e.g., Atelopus cruciger, Leptodactylus fuscus, and Phyllomedusa trinitatis), with mean SVL differences ranging from 4 to 15 mm (p < 0.05). This study provides the first reference AW values for these species, contributing novel data for morphometric studies. Four species (Boana punctata, Leptodactylus fuscus, Rhinella marina, and Scinax rostratus) showed no significant differences in SVL or AW (p > 0.05), indicating limited SSD or monomorphism. Statistical analyses highlighted geographic variation in SVL, with female-biased SSD more pronounced in arboreal species and male-biased SSD associated with territorial, burrow-digging behaviors in terrestrial species (p < 0.05). These findings support Renschs rule, where SSD scales with body size: SSD decreases with increasing female size and increases with male-biased size. In L. fuscus, for instance, SVL values (males: 54.5 mm; females: 61.56 mm) exceeded reported ranges but lacked statistical significance (p = 0.595), highlighting substantial geographic and ecological influences. Directional asymmetry was evident in arboreal species, linked to their ecological adaptations for locomotion. Conversely, terrestrial species displayed larger size variation associated with competition and reproductive strategies. Statistical tests demonstrated the role of ecological traits, activity patterns, and reproductive pressures in shaping SSD (e.g., p < 0.01 for differences in tree vs. ground-dwelling species). This study underscores the complexity of SSD, influenced by ecological, behavioral, and geographic factors. Morphometric indices validated here offer practical tools for future studies, requiring careful application across species, populations, and developmental stages. The results emphasize the ecological and evolutionary importance of body size variation and provide critical data for conservation efforts in Venezuelan anurans.

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Canizales, I.. 2024-11-20. Body Size Variation And Sexual Dimorphism In Eleven Species Of Venezuelan Anurans. https://doi.org/10.1101/2024.11.19.624291

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