Can neutral genetic differentiation explain geographical variation in body size of the natterjack toad, Epidalea calamita?

MARANGONI, F.

Ciudad Autonoma de Buenos Aires

Congreso; XXIII Congreso Argentino de Herpetología; 2023

Asociación Civil Herpetológica Argentina

Population genetic studies are crucial for evolutionary biologists because the population is the basic substrate on which evolution is forged. However little empirical evidence has been able to demonstrate the role that isolation and gene flow play in maintaining differentiation in populations at short geographic scales. Epidalea calamitaexhibits a steep variation in body size and reproductive traits in southwestern Spain, associated with changes in thegeological substrate. This implies a decrease of 70.9% of body mass and 28.5% in snout-vent length, on a micro-geographic scale of only 110 km. Previous results from both metamorphic and juvenile common garden experimentsshowed that genetic differentiation may be a causal determinant of geographic variation in adult. This study testedwhether neutral genetic differentiation can explain the geographical variation in the body size observed in E. calamita.It was addressed analyzing the level of genetic structuring and gene flow among populations along the cline, comparing the genetic diversity between and within populations, as well as between ecological environments. The studyshowed that the geographic variation in body size observed in E. calamita has evolved in absence of geographic isolation, with moderate gene flow connecting the populations. Thus, neutral genetic differentiation cannot explain thegeographical variation observed. Future studies are needed on the interaction between the genetic component withthe environmental factors and will be necessary to analyze the contribution of the maternal effects in the origin andevolution of the geographical variation in the body size observed in E. calamita from southern Spain