Meeting Abstract
Hybridization is a driving force for the loss of biodiversity worldwide, and is of particular concern for freshwater fishes. Reproductive isolating mechanisms play a role in hindering hybridization, but for closely related allopatric species, reproductive isolating mechanisms can break down when the species come into secondary contact with each other. Pre-mating isolating mechanisms include those related to sexual selection. Typically, sexual selection includes female mate choice and male-male competition. This may not only occur within a species but also between species. To identify any break down in reproductive isolation that may facilitate hybridization, experimental studies of female preferences and male competition were conducted on two Cyprinodon species. Cyprinodon rubrofluviatilis is a common species in the Red and Brazos river watersheds, but the introduction of C. variegatus poses a threat to the status of C. rubrofluviatilis. Cyprinodon variegatus has been introduced to habitats of other Cyprinodon in the southwest United States, where hybridization and introgression has been extensive. Female preference trials quantifying association time were used to identify if either species prefer conspecific males to heterospecific males. Male-male competition trials replicated secondary contact and quantified aggressive behaviors. Males of many Cyprinodon spp. defend territories to attract females, therefore if one species is more aggressive, they may control more or higher quality territories at spawning sites. Understanding behavioral interactions that may promote heterospecific matings is critical to management strategies in systems threatened by hybridization.
