RUI: DIVERSIFICATION AND RADIATION OF THE SPLITFINS (TELEOSTOMI: GOODEIDAE)

Southeastern Louisiana University, Hammond LA

Investigators

Abstract

The Cyprinodontiformes, commonly known as splitfins, are a diverse order of teleost fishes consisting of 10 families, and more than 800 globally distributed species. The group includes killifishes, guppies, and swordtails, and is well known among aquarium hobbyists, toxicologists, and as a model organism in cancer research. Goodeids are an imperiled group of freshwater fishes that occur in Mexico and the Southwestern United States and consist of two main lines of diversification; a depauperate group of egg laying species, and a speciose group that bear live offspring. Many groups in the order, including the viviparous (live birthing) species, are understudied from an ecological and evolutionary perspective.The evolutionary relationships of groups within the order are unclear and the relationships of the species and genera within the Goodeidae family have not been adequately studied. The lack of a robust family tree has impeded both basic and applied research on the splitfins. Resolving the evolutionary relationships within the Cyprinodontiformes, as well as within the Goodeidae species, will advance our understanding of life-history evolution, morphological diversification, taxonomy, and conservation. The researchers will write a handbook for aquarists and conservation biologists containing recommendations for maintenance and breeding guidelines for maintaining genetic and phenotypic diversity of goodeids in captivity. The researchers will work with the Goodeid Working Group to update the Goodeidae conservation status and trends information as well as contribute to aquarist-oriented publications and conventions to promote appropriate captive Goodeidae rearing. These efforts will enhance conservation efforts of these fishes which are critical to resource managers especially considering the ongoing environmental changes in the areas occupied by the Goodeidae. This integrative project will involve multiple graduate and undergraduate students, international and United States collaborators, and citizen scientists. Specimens will be collected in the United States and Latin America and the vouchered tissue samples, which are important for future studies, will be deposited in research collections in the United States and Mexico. Citizen scientists will provide pedigreed larval specimens of all species of Goodeidae. These are historically difficult to obtain and will be used for scanning electron microscopic examination of trophotaeniae, a poorly understudied larval taxonomic character that is critical to the unusual live births in this group. This study will result in the construction of phylogenetic trees for the Cyprinodontiformes and the Goodeidae based on traditional (10 loci, and >7,000bp sequence data) and next generation sequencing approaches (anchored phylogenomics), offering the most comprehensive tests of previous phylogenetic hypotheses for these groups. The incorporation of geometric morphometric and trophotaenial data, fossil calibrations, and phylogenetic comparative methods will allow for a better understanding of the timing of diversification and the factors that have played a role in radiation of this interesting group of fishes. Finally, the research will assess changes in Goodeidae abundance and distribution, based on museum records and field sampling.