OFFICE OF FELLOWSHIPS AND GRANTS SCHOLARLY STUDIES PROGRAM Proposal Cover Sheet Name: S.I. Address & Phone: Principal Investigator: Robert Hershler Department of Invertebrate Zoology National Museum of Natural History NHB E-518 (202) 786-2077 Co-Principal Investigator(s). Hsiu-Ping Liu Biology Department Montclair State University Upper Montclair, NJ 07043 Collaborator(s): None Proposal Title: Phylogeny of Pyrgulopsis Springsnails, a Major Component of North American Aquatic Biodiversity: Implications for Systematics. Biogeography, and Conservation Start Date and Duration of Project: September 1, 1998,. two years Budget Request: Year 1 $28,970 Year 2 $33,536 Total $62,506 P.I.'s Unit Organization Code: 3380 Signatures: Date: Principal Investigator 3/23/98 Co-Principal Investigator 3/23/98 NON-SPECIALIST SUMMARY We request funding to continue and expand a multidisciplinary and collaborative research program on the evolution and biogeography of western American springsnails of the family Hydrobiidae. Although the West provides an outstanding theater for such studies because of its complex and historically dynamic landscape, previous work focused on a single group, fishes. Hydrobiids are an equally suitable study group and also offer distinct advantages over fishes as a consequence of the small size and limited dispersal abilities of these snails. Prior funding from the Scholarly Studies Program enabled us to construct a robust phylogenetic hypothesis for a component of this fauna (genus Tryonia, 21 species) based on mitochondrial DNA sequences (mtCOI gene), thus removing the major "roadblock" that had prevented full utilization of hydrobiid snails in evolutionary and biogeographic studies. (The morphological characters provided by these snails have thus far proved insufficient in this respect.) Our study was also encouraging as patterns of snail distribution and evolution were partly congruent with those documented for pupfish (Cyprinodon) and provided evidence that an important regional drainage, the Amargosa River basin, is not only a biotic, but also a geologic composite, in congruence with the complex tectonic history of the Death Valley region. Based on the successful and exciting results of the Tryonia project, we propose a similar phylogenetic analysis, but much more comprehensive biogeographic analysis of another western hydrobiid, Pyrgulopsis, the largest genus of nonmarine snails in North America (123 extant species). Our study will determine whether this anatomically heterogeneous and confusing group represents a clade (a group of species that includes an ancestral species and all of its descendants), delineate evolutionary structure within the group, provide needed taxonomic stability, and evaluate whether morphological characters are congruent with a molecular-based phylogeny of these snails. We anticipate that the few broadly ranging congeners will be revealed as large species complexes - we will document these discoveries by publishing formal taxonomic descriptions and share relevant information with regulatory agencies seeking to conserve and manage aquatic ecosystems in the West. Finally, we will use our phylogenetic hypothesis as the basis for an analysis of historical relationships of areas inhabited by these snails (vicariance biogeography), which will be evaluated for congruence with relevant geologic history and contrasted with previous such studies of other regional organisms. We will conduct fieldwork to obtain fresh material for DNA analysis. We will sample most of the diversity in this group, including various undescribed congeners which can provide biogeographic resolution of otherwise unrepresented geographic areas. The fossil record suggests a minimally Miocene age for both Pyrgulopsis and Tryonia, and thus we assume that the mtCOI gene will be similarly informative for this study. We tested this by analyzing a small sub-set of Pyrgulopsis and related groups, the results of which confirmed the resolving power of this gene and indicated encouraging congruence with morphological-based hypotheses concerning snail relationships. As a large number of characters will be necessary to well resolve the phylogeny of this huge group, we will sequence this entire gene, as well as a second gene (probably mtC0II). This project benefits from the complementary skills of the participants. Hershler has been been conducting field surveys and studying the systematics and morphology of western hydrobiids for 20 years while Liu is expert in molecular analyses and is interested in applying these techniques to evolutionary processes of mollusks. ii INTRODUCTION. This requests funding to continue and expand research on the evolution and biogeography of western American springsnails of the family Hydrobiidae. The West is extremely fertile ground for such studies because aquatic elements are profoundly isolated by inhospitable deserts and mountain ranges, live in extremely restricted and/or harsh environments, and provide distributional and phylogenetic patterns which have been molded by the extremely complex and dynamic Cenozoic history of the region (Minckley et al. 1986). Whereas early biogeographic treatments of fishes (e.g., Hubbs and Miller 1948; Hubbs et al. 1974) focused on dispersal opportunities provided by a highly integrated late Pleistocene ("pluvial") regional drainage, Minckley et al. (1986) accepted great antiquity (Oligocene- Miocene) of this fauna and consequently emphasized the complex role of geological events in effecting vicariance. In this seminal work they provided a model for historical relationships of western areas (Minckley et al. 1986:figs. 15.4, 15.5) and set the stage for a new era in the study of regional biogeography, yet few pertinent phylogenetic hypotheses have since been generated and these have focused almost exclusively on fishes (e.g., Echelle and Dowling 1992; Smith 1993; but also see Hendrickson 1986). Hydrobiid snails, the most diverse family of freshwater snails in North America (Turgeon et al. 1998), share many attractive features for evolutionary and biogeographic studies with fishes, as well as providing distinct advantages over them. The regional age of both groups is minimally Paleogene (Taylor 1985; Minckley et al. 1986), and thus these organisms are suitable for evaluation of old biogeographic relationships. Hydrobiids are obligate to water and disperse slowly, features which link them tightly with drainage history (Taylor and Bright 1987) and make them ideal tools for evaluating biotic response to vicariance. Hydrobiids exhibit a much greater degree of local endemism than fishes, and they sometimes comprise "species flocks," 1 including several spectacular faunas in spring systems (Taylor 1966b). These tiny snails often persist in poorly watered basins devoid of ichthyofauna and do not appear to be subject to introgression, which commonly occurs in the more mobile fishes (Smith 1992), and thus they can provide a more comprehensive and a clearer biogeographic signal than their vertebrate counterparts. Despite the unique and compelling features of western hydrobiids, an absence of rigorously proposed phylogenetic hypotheses has limited the use of these animals in evolutionary and biogeographic studies, although they have figured prominently in development of provocative, albeit non-phylogenetic scenarios for western drainage history (Taylor 1985, 1987; Taylor and Bright 1987). The few, morphology-based phylogenetic studies of hydrobiids resulted in poorly resolved trees and indicated that most characters are homoplasic (e.g., Ponder et al. 1993; Hershler 1994), and although results may be improved by more finely discriminating characters and their states (Hershler and Ponder 1998), there is a need for infusion of additional data sets. As a first step toward removing this "roadblock," we obtained funding from the Scholarly Studies Program in 1994 to examine monophyly and phylogenetic structure within one of the larger western genera, Tryonia, using allozymes and, ultimately, mitochondrial DNA sequences, and have produced extremely promising results (Hershler, Mulvey and Liu 1998; Hershler, Liu and Mulvey 1998). Partial sequences from the mitochondrial cytochrome-c- oxidase subunit I (mtC0I) gene suggested the presence of cryptic species and permitted generation of well-resolved trees which indicated that the genus, as currently constituted, is polyphyletic. Subsequent anatomical studies of these taxa (which had never been monographed) revealed congruent heterogeneity in female genitalic groundplan (RH, unpublished), suggesting that molecular analyses can have an important predictive function in such cases. Phylogenetic 2 structure within the clade composed of "true" Tryonia (16 species) generally corresponded with timing of pertinent vicariant events beginning in the late Tertiary and exhibited some commonality with biogeographic pattern described for pupfish (Cyprinodon; Minckley et al. 1986; Echelle and Dowling 1992). Based on this analysis, the Amargosa River basin (whose lower segment is Death Valley) was identified as a biotic and geologic composite (fide Platnick and Nelson 1984), in congruence with the complex tectonic history of the area. PROPOSAL. We propose to continue this research program in the form of a collaborative, multidisciplinary study of the evolution and biogeography of Pyrgulopsis, the most diverse genus of nonmarine mollusks in North America (131 Recent species, 123 of which are extant; Hershler 1994, 1995, 1998; Thompson 1995), which is broadly