Biologia reprodutiva e dieta de Ameerega picta (Tschudi, 1838) (Anura, Dendrobatidae) na borda oeste do Pantanal de Mato Grosso do Sul

Abstract

Limitations to survival, development and reproduction are directly linked to an individual's niche concept. Along with these characteristics, biotic interactions and habitat availability will define where populations occur throughout the species' distribution. Peripheral populations are likely to experience environmental and geographic limits. The present work aims to investigate the reproduction and diet of Ameerega picta, located on the western edge of the Pantanal. We carried out monthly collections between August 2019 and February 2020 through visual and auditory encounter techniques. We analyzed the relationship between the number of oocytes, snout-vent length (SVL) and body mass (BM) of females, reproductive effort (RE) relationships with possible predictors for both sexes. We investigated which prey make up the diet of A. picta and whether stomach volume (SV) is related to sex and SVL. We used linear models, represented by biological hypotheses, and then we selected models based on the Akaike criterion. The species showed sexual dimorphism, with females larger and heavier than males. The BM of the females was a good predictor for the number of oocytes, without influence of the SVL. The number of mature oocytes was the best predictor of female gonad mass. For RE of females, BM was the best predictor, whereas for males, two hypotheses were accepted: the first demonstrates that the RE is uniform in relation to the SVL, and the second indicates that males of intermediate sizes have higher RE values. The main prey found were ants, wasps, termites, mites and beetles, with ants having the highest relative importance index. The SV was not influenced by sex, but by SVL, demonstrating that larger anurans consume more prey. Ant consumption is recurrent for dendrobatids due to the sequestration of alkaloids stored in their skin. The presence of sexual dimorphism may be linked to the role of males in parental care during reproductive periods. It is concluded that the SV is influenced by the SVL, the number of oocytes is dependent on the BM, the gonad mass is associated with the number of mature oocytes and the RE of males is independent of the SVL or BM, with a second model showing males of intermediate sizes with extreme RE values.