Meeting Abstract

P2-157    They’re still alive?! Morphological variation across replicate, 16-year-old, self-sustaining, quasi-natural, mosquitofish mesocosms Hoover, RC*; Curtis, PM; Leberg, PL; Kane, EA; University of Louisiana at Lafayette; University of Pittsburgh; University of Louisiana at Lafayette; University of Louisiana at Lafayette richard.hoover1@louisiana.edu

Mosquitofish ( Gambusia affinis ) have become a model system for examining ecomorphological patterns and show consistent phenotypic trends when exposed to environmental pressures such as fish predation, salinity, and flow regime. These patterns have been described by observing variation in natural populations and experimentally testing common garden crosses in controlled environments. However, we have access to replicate, 16-year-old, self-sustaining, quasi-natural, mosquitofish mesocosms. The mesocosms were established to test salinity tolerance in mosquitofish from freshwater and brackish sources across two drainages in Louisiana. We examine linear morphometric traits of fish from mesocosm and natural sites to describe how mesocosm fish have adapted to their current conditions. A preliminary principal component analysis of 8 measurements shows wide variation across samples, but that diversification in some head size and body height traits may be apparent between natural and mesocosm sites, as well as across mesocosms. These unique fish allow us to gain insight into adaptation to a novel, human-influenced environment that is potentially divergent from contemporary natural systems.