Meeting Abstract
Selection, both natural and sexual, has the ability to produce morphologies that increase performance of individuals. While many studies examining this ability have focused on the effects of shape, for many paired structures the degree of symmetry has also been shown to impact performance. As a result, the morphology of traits vital for locomotion (e.g., legs or wings) or reproduction (e.g., sexually-selected ornaments or weapons) may rely more heavily on overall symmetry to remain functional than other non-vital structures, and therefore may be more developmentally constrained. Fluctuating asymmetry (FA) refers to deviations from perfect symmetry in bilateral structures and may serve as a useful tool in evaluating the strength of selection acting on individuals. In the sand cricket (Gryllus firmus), two distinct morphs with unique life histories exist: Short-wing (SW) morphs are incapable of flight, but have high reproductive potential as early adults; long-wing (LW) morphs have enlarged wings for dispersal, but produce fewer offspring and do so later in life. Early reproduction in SW morphs places stronger selective pressures on reproductive structures, while dispersal in LW morphs places stronger selective pressures on locomotor structures. Because the two morphs rely on different body structures to maximize their fitness, and because many structures used by males for courtship and fighting do not serve the same function for females, we expect to see predictable differences in FA both between morphs and sexes.
