Ancient vicariance and recent dispersal of springsnails (Hydrobiidae: Pyrgulopsis) in the Death Valley system, California-Nevada

Abstract

The Death Valley system (southeastern California and southwestern Nevada) contains a locally endemic aquatic biota that has long been the subject of compelling biogeographic speculation, yet it remains little studied phylogenetically. Springsnails (Hydrobiidae: Pyrgulopsis) are one of the most diverse elements of this fauna, and they are thought to have evolved in association with late Tertiary rearrangements of landscape and drainage. We assembled a molecular phylogeny for this fauna to investigate its evolutionary development in relation to regional geological history. Sequences for two mitochondrial genes were obtained from 80 populations representing 13 of the 14 Death Valley system springsnail species, and 31 extralimital congeners. Combined analyses of the 1188 base-pair data set consistently depicted the Death Valley system fauna as a polyphyletic assemblage of eight or nine lineages. Based on a molecular clock, the six lineages endemic to the Death Valley system were estimated to be minimally Pliocene in age, which is concordant with inception of regional topographic closure during this time period. The single endemic lineage with a well-resolved sister relationship was closest to a species from the upper Gila River basin, which also suggests an old divergence event. Three other lineages shared a pattern of shallow structuring (divergence events younger than 0.7 Ma) across multiple drainage basins, some of which have long been isolated. This suggests that, contrary to previous thought, regional springsnail biogeography has been shaped in part by geologically recent (Pleistocene) dispersal, and, in some places, it has occurred by means other than spread through continuous reaches of aquatic habitat.

Two new Truncatelloidea species from Melissotrypa Cave in Greece (Caenogastropoda)

“…The genetic distance between Daphniola magdalenae and Daphniola exigua is p = 0.1325. Based on mtCOI clock calibrations of 1.83% per million years for European Hydrobiidae (Wilke 2003) and 1.62% per million years for Pyrgulopsis (Hershler and Liu 2008), the estimated divergence times of the two species ranged from 7.24 to 8.20 mya, thus the very beginning of the Messinian or even upper Tortonian in the Miocene.…”

Phylogeography of an endangered Western North American springsnail

“…2b) Table 1 Collections used for molecular analysis, with population sample numbers (used in Fig. 1), locality details (temperatures given for the P. bruneauensis localities), sample sizes (n), and GenBank accession numbers Hershler and Liu (2008) b Hershler and Liu (2004) c Hershler et al (2003) in the Bayesian tree; the sister taxon of this lineage was not resolved. One of the haplotype groups delineated by TCS (group A) formed a well supported clade in the Bayesian tree while the other (group B) was paraphyletic.…”

“…A molecular clock hypothesis for the Bayesian topology (52 sequences) was tested using Tajima's (1993) non-parametric relative rate test in MEGA5 (Tamura et al in press). A molecular clock rate of 1.62% COI divergence per million years, based on the geology-calibrated divergence of a Pyrgulopsis sister species pair (Hershler and Liu 2008), was used to estimate divergence times. Intra-population diversity and structuring of genetic variation among populations was assessed using Arlequin 3.5 (Excoffier and Lischer 2010).…”

Systematics of a widely distributed western North American springsnail, Pyrgulopsis micrococcus (Caenogastropoda, Hydrobiidae), with descriptions of three new congeners

“…Sequences were determined for both strands and then edited and aligned using Sequencherä version 5.0.1. The 51 newly sequenced specimens were analyzed together with our previously published Pyrgulopsis micrococcus dataset (Liu et al 2003, Hershler and Liu 2008). The new haplotypes from each sampling locality were deposited in GenBank (accession numbers KF559184-KF559202).…”

“…This species was subsequently revised to include additional populations scattered within large portions of the Mojave Desert (southeastern California and southwestern Nevada) that resembled specimens from the type locality area in having a globose to ovate-conic shell and distally lobate penis with a terminal gland (sometimes reduced or absent) on the ventral surface (Hershler and Sada 1987, Hershler 1989, Hershler and Pratt 1990). A recent phylogenetic analysis resolved mtDNA sequences from 29 populations of Pyrgulopsis micrococcus into five deeply divergent, allopatric clades–one of which also included morphologically similar and geographically proximate Pyrgulopsis turbatrix Hershler, 1998–which were postulated to be distinct species (Liu et al 2003, also see Hershler and Liu 2008). In this paper we detail previously unrecognized shell and penial differences supporting recognition of three of these lineages as new species which we describe herein while also clarifying the limits of Pyrgulopsis micrococcus and Pyrgulopsis turbatrix .…”