Temporal stability in color patterns and body size variation in a six-year monitored population of the aposematic toad (Melanophryniscus rubriventris)

LUCÍA VALERIA SOMMARO; JUAN JOSÉ MARTÍNEZ

EVOLUTIONARY ECOLOGY

SPRINGER

Lugar: Berlin; Año: 2023 vol. 2 p. 1 - 13

0269-7653

Color polymorphisms in poison frogs have intrigued evolutionary ecologists, as understandingthe mechanisms that sustain them is of great interest. Temporal variation in selectionis considered crucial for maintaining color polymorphism, and monitoring aposematicsignals provides valuable insights into such temporal dynamics. We conducted a six-yearstudy on red-belly toads, Melanophryniscus rubriventris, analyzing color patterns andbody size variation across five reproductive seasons. Our findings show stable color morphratios over time, with no discernible differences between sexes and no interdependencebetween dorsal and ventral patterns. Notably, darker morphs, mostly melanic, comprisedonly about 25% of the population, contrasting with the higher frequency of conspicuousaposematic combinations. Intermediate morphs were more prevalent, while the mostextreme conspicuous dorsal pattern was rare. Regarding body size, females were significantlylarger and in better body condition than males. We observed a significant decreasein snout-vent length for males between 2021 and 2022, while females showed a significantincrease between 2020 and 2022. Interestingly, there was a phenotypic associationbetween color patterns and body size, with males exhibiting black bellies having smallersnout-vent lengths compared to those with other ventral patterns, particularly red bellies.Our study suggests that dorsal and ventral color patterns may respond differently to selection.The stability of color patterns within the population could be upheld through complexinteractions involving stabilizing and sexual selection. We emphasize the importance oflong-term studies and recommend that future research considers reproductive ecology andindividual behavioral decisions in this polymorphic aposematic species. By incorporatingthese aspects, we can gain a more comprehensive understanding of the mechanisms drivingphenotypic variation