LANDSCAPE INFLUENCES ON SPECIES ASSEMBLAGE PATTERNS OF ICTHYOFAUNA IN TEXAS, NEW MEXICO, AND OKLAHOMA
Sparks, Levi L
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With the influx of GIS in recent years, there has been an enormous increase in biogeographic analyses. However, many studies still focus on small areas with limited environmental components and rarely cross political boundaries. These inadequecies are extremely apparent in the fisheries world. My study looked at the species of fishes found in the states of Texas, New Mexico, and Oklahoma, because of how closely intertwined these river systems are and the wide diversity of habitats and environmental variables found in these states. Using numerous sources, I compiled a comprehensive list of fish species within the 3 states and then reduced that total number to the 249 species that had the most records, resulting in a total of 172,214 individual, mappable locations which were then imported into a GIS. I then used 8-digit Hydrolaugic Unit Classifications to relate landscape, geographic, basin characteristic, and climate variables to fish distribution using a Canonical Correspondence Analysis. The CCA revealed 4 different communities within the study area. These communites were labeled as a coastal community, a eastern and generalist community, a western community, and a Pecos/Devil’s River community. The relationships between these communities and the variables allowed strong conclusions as to the biology and the evolution of these fish species. While 3 of the communities incorporated large amounts of the study area, it is interesting to note that the Pecos/Devil’s River community of fish arose from our study which, in the terms of the other communities, is an extremely small area, pointing either to the fact that these species are much more dependent on landscape variables for their evolution or that the species of fish found within these river systems are very distinct from any other communities of fish found within the rest of the 3 states. The overall patterns lead me to suggest that the western species of fish from this study area evolved on a more landscape scale while the eastern communites of fish are much more dependent of microhabitat scaling.