Características reprodutivas das espécies explicam diferenças no investimento em tamanho dos armamentos presentes nos machos? Uma meta análise

Abstract

Sexually selected traits, such as male weapons, are highly variable in both shape and size among species. However, little is known about the mechanisms that may shape this variation. Since males with greater investment in weapon size tend to win more fights, but pay higher costs related to the development and maintenance of weapons, large weapons should be expected only in species in which victory in male-male fights generates reproductive benefits that offset the investment costs. Therefore, we hypothesize that the reproductive characteristics that favor the certainty of winners to access females or to increase paternity will favor the evolution of large weapons. To test this hypothesis, we conducted a meta-analysis in which we investigated whether variations in three reproductive characteristics related to the certainty of accessing females or of paternity with victories can predict investment in weapon size. We used arthropods as a study model and, to measure weapon investment, we gathered Pearson correlation coefficient values for the relationship between weapon size and body size. We found that none of the reproductive characteristics we investigated was related to male weapon size. Thus, it seems that greater certainty of accessing a female or fertilizing brood with a victory does not modulate the investment in male weapon size. Perhaps the cost-benefit relationship between weapon size investment and reproductive success is not the main factor driving the variation in investment in weapon size.