Biodiversity, Biogeography, & Conservation of North American Desert Fishes I: Areas of Endemism

Authors: Christopher Hoagstrom, Derek Houston, Norman Mercado-Silva

Year: 2018

Abstract

A literature review of phylogenetic diversity indicates that North America hosts 333 lineages of fishes restricted to the desert region (i.e., the region with <0.65 aridity index). These ‘desert endemics’ have diverse distributions from large river basins to small springs. A comparison of endemic-lineage distributions with modern and prehistoric drainage boundaries reveals 30 distinct areas of endemism, with endemic lineages per area ranging from 1 to 43 (mean = 15 ± 11 SD). Faunal composition in each area is unique. Although some ‘widespread’ endemics occupy multiple areas of endemism that have a history of interconnection, 82% of endemics are restricted to single areas, and no endemics occupy more than five areas. A major biogeographic boundary subdivides the region into Northern Great Basin-Colorado Plateau (13 areas) and Southern Desert-Eastern Steppes (17 areas). Only 3% of desert-endemics span this boundary. These either dispersed between the upper & lower Colorado River basin following the formation of the Grand Canyon or crossed between the Lahontan and Mojave areas of endemism via Mono Lake. Thus, desert-fish conservation should target all areas of endemism individually and collectively to ensure preservation of native biodiversity.