Meeting Abstract
The predicted drastic changes in global precipitation levels and distribution will lead to drought like conditions in previously abundantly wet areas. Poecilia spp. are livebearers and are ubiquitously distributed across the Americas. In this study we employ them as a model to elucidate which traits are evident in the dry populations, in an attempt to understand the processes governing adaptations in shifts from wet to dry environments. A hierarchical sampling scheme was employed where eight species of Poecilia were collected across wet Central and dry northern South America. Specimens were analyzed for various reproductive parameters, muscle tissue analyzed for carbon and nitrogen stable isotopes, and geometric morphometrics performed. A significant effect of precipitation regime was observed between environments (perMANCOVA: Pseudo-F = 30.08, d.f. = 1, 729, P < 0.001). PerANCOVAs (mean ± SE) showed that Poecilia in the wet environment were more massive (0.56±0.36 vs. 0.29±0.01 g dry mass), produced significantly more massive eggs (2.8±0.58 vs. 2.1±0.25 mg dry mass), and neonates (2.1±0.48 vs. 1.6±0.051 mg dry mass). However, fewer eggs (22±1.0 vs. 28±1.4 eggs) and lower reproductive allotment (12±4.0% vs. 17±8.3%) were observed in the wet environment. Species in the dry environment invested less heavily in reproduction, but produced disproportionately fewer but larger neonates, suggesting that a greater abundance of offspring (albeit smaller) are required to persist in drier environments. Additionally, reproductive biology will be discussed in light of trophic ecology (Carbon and Nitrogen stable isotopes) and ecomorphology (linking trophic ecology with geometric morphometrics).
