Phylogeography and population structure of the imperiled redtail splitfin (Xenotoca eiseni): Implications for conservation.

摘要

The Mesa Central of Mexico is an area with a high degree of freshwater diversity, and is subsequently a focal point for many freshwater fish conservation studies. The livebearing subfamily Goodeinae (Teleostomi: Goodeidae) is a diverse group, endemic to this area, that is under threat from many anthropogenic factors. Xenotoca eiseni, commonly known as the redtail splitfin, is a member of this subfamily, and has a fragmented distribution in the Western basins of the Pacific Coast including the Rios Grande de Santiago, Compostela, Ayuquila, Coahuayana, and the endorheic Lago de Magdalena. Previous studies have noted high levels of genetic differentiation between the endorheic Lago de Magdalena basin and surrounding areas which may be indicative of more taxonomic diversity within Xenotoca eiseni than currently recognized. The objectives of this study were to use mitochondrial (cytochrome b) and nuclear (ITS-1) DNA sequences and microsatellite data to assess phylogeography, genetic differentiation, and population structure between and within populations of this species. Analysis of the data resulted in two deeply divergent clades, with a nucleotide difference of 2.51% within cytochrome b and 0.88% within ITS-1 between populations in the endorheic Lago de Magdalena basin and all other locations. These two monophyletic clades therefore may represent distinct species. Microsatellite data also found significant structuring within these two clades of Xenotoca eiseni, and identified five operational conservation units (OCUs). Because each of these units contains a proportion of the total variation within the species, they should each receive conservation attention and protection.;Key words: conservation, Goodeidae, Mexico, redtail splitfin, Xenotoca