Biometric and sexual dimorphism variation of <em>Hydromedusa tectifera</em> in Brazil

Abstract

Body size has a strong influence on the ecology and evolution of organisms’ life history. Turtle species can exhibit variation in body size and shape between populations of conspecifics through usually broad geographical scales. This prediction is timely to be tested in this study with the species Hydromedusa tectifera. We aimed to evaluate the variation in body size between and sexual dimorphism within populations of H. tectifera in two areas in Brazil. Sampling occurred in Minas Gerais and Rio Grande do Sul states in order to obtain morphometric measures of carapace and plastron of the individuals. We observed sexual dimorphism within populations. In Rio Grande do Sul state, females were larger than males in most of the carapace and plastron measures. In Minas Gerais state, males were larger than females regarding maximum carapace width. Overall, individuals from Rio Grande do Sul state were larger than those from Minas Gerais state. We discuss possible factors that might cause variation in morphology within and between populations of conspecifics. Research on morphology is encouraged to facilitate comparisons among populations in geographically broad areas.

Ecology of Phrynops geoffroanus and Mesoclemmys tuberculata (Testudines: Chelidae) in Climatically Distinct Areas of the Semi-Arid Caatinga and Atlantic Forest in Northeast Brazil

“…Variations in ecological aspects, such as morphological characteristics, often result from different seasonal regimes and have been described for several vertebrates (Leclair and Laurin 1996;Bitto and Egbunike 2006), including reptiles (Clavijo-Baquet et al 2010;Lucas et al 2020). With regard to turtles, seasonal differences can drive different ecological pressures that affect their size (Clavijo-Baquet et al 2010;Litzgus and Smith 2010;Lucas and Bager 2017).…”

“…Species that occupy large areas with significant environmental variation may vary significantly in their autoecology (Clavijo-Baquet et al 2010; Litzgus and Smith 2010). Morphological variation is commonly observed in turtle populations (Lucas et al 2020). However, it is difficult to quantify and identify the evolutionary processes that have shaped such variation due to the complex interactions between the phenotype and the behavior of these animals (Delmas et al 2007; Litzgus and Smith 2010).…”