The evolution of male-biased sexual size dimorphism is associated with increased body size plasticity in males

摘要: 1. Sexual size dimorphism (SSD) can vary drastically across environments, demonstrating pronounced sex-specific plasticity. In insects, females are usually the larger and more plastic sex. However, shortage of taxa with male-biased SSD hampers assessment whether greater plasticity in is driven by selection on or represents an effect female reproductive role. Here, we specifically address role body evolution reversals to disentangle sex effects. 2. We first investigate Sepsis punctum neocynipsea as two independent cases intraspecific sepsid flies. both species, directional variation between populations stronger sexual male size. Using controlled laboratory breeding, find evidence for increased condition dependence SSD, but not female-biased SSD. 3. To extend comparative scope, next estimate eight additional fly species that differ direction under conditions. all males be sex, while this was only rarely case thus suggesting a general trend Diptera. 4. examine generality pattern holometabolous combine our data from literature meta-analysis. Again, tends than when though now also generally larger. 5. Our findings indicate primarily size, rather per se, drives flies, possibly Diptera general, show clear asymmetry related likely strong males. Although further research controlling phylogenetic ecological confounding effects needed, congruent theory plays pivotal dimorphism.