Session 1, Abstract 3


Nathan Hung Nghia Nguyen* (Matthew Cover), California State University Stanislaus, Dept. of Biological Sciences, One University Circle, Turlock, CA 95382.

Although the landscape genetics of a number of aquatic insect species have been investigated, little is known about the phylogeography of temporary stream specialists. Neohermes filicornis is a large aquatic insect in temporary streams of the California coast range, southern California, and Arizona; while a sister taxon, N. californicus, is distributed in the Sierra Nevada, north to Oregon. A third species, N. inexpectatus, was recently described and only known from one living population in northern California (Mendocino County). The objective of this study was to understand the phylogeography of Neohermes in the western USA as part of a larger study of the ecology and evolution of these taxa. We obtained Neohermes specimens, sequenced the DNA barcoding gene (mtDNA COI), and built phylogenetic trees using both distance matrix and Bayesian methods. We found that N. inexpectatus was sister to all other western populations of Neohermes. Distinct clades were identified based primarily on geographic separation; however, our data did not support the monophyly of N. filicornis and N. californicus. Rather, N. filicornis from the central California coast were more closely related to N. californicus specimens than to other populations of N. filicornis. Our preliminary results indicate that patterns in phylogeography using mtDNA do not support the delineation of species based on morphological characteristics (primarily male genitalia). Additionally, large differences (5%) among neighboring populations (e.g., Sonoma/Napa clade and Bay Area clade) suggest historical biogeographic barriers to gene flow. We aim to further test these findings using phylogenies based on nuclear genes.

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