Extreme population subdivision throughout a continuous range: phylogeography of Batrachoseps attenuatus (Caudata: Plethodontidae) in western North America

Abstract

Low-vagility species with deep evolutionary histories are key to our understanding of the biogeographical history of geologically complex areas, such as the west coast of North America. We present a detailed study of the phylogeography of the salamander Batrachoseps attenuatus (Caudata: Plethodontidae) using sequences of the mitochondrial gene cob from 178 individuals sampled from throughout the species' range. Sequences of three other mitochondrial genes (16S, cox1, nad4) and a nuclear gene (RAG-1) were used to investigate the deeper evolutionary history of the species. We found high levels of genetic diversity and deep divergences within a mostly continuous distribution, with five genetically well-differentiated and geographically structured mitochondrial DNA clades. Significant association between geographical and genetic distances within these clades suggests demographic stability, whereas Fu's FS tests suggest demographic expansions in three of them. Mantel tests identify two biogeographical barriers, the San Andreas Fault and the Sacramento-San Joaquin Delta, as important in the diversification of lineages. The timing of the main splitting events between intraspecific lineages was estimated by applying relaxed molecular clock methods combining several mutation rates and a fossil calibration. The earliest splitting events are old (Pliocene/Miocene), with more recent (Pleistocene) subdivisions in some clades. Disjunct populations distributed along the western foothills of the Sierra Nevada colonized this area relatively recently from a single refugium east of San Francisco Bay. The combination of fine-scale, comprehensive sampling with phylogenetic, historical demographic and hypothesis-based tests allowed delineation of a complex biogeographical scenario with general implications for the study of codistributed taxa.

Mitochondrial DNA Data Unveil Highly Divergent Populations within the Genus Hynobius (Caudata: Hynobiidae) in South Korea

“…As a consequence, genetic studies are essential for revealing potential cryptic species (Fu et al, 2003;Martínez-Solano et al, 2007). In the present study, using mtDNA cyt-b gene and 12S rRNA, we successfully determined species identification and phylogenetic relationships among Hynobius species in South Korea.…”

“…This allopatrical distribution could have been affected through geographic isolation and/or behavior characteristic. Salamanders are known as having low vagility and physical barriers such as mountains, deserts, and rivers can prevent their dispersal (Martínez-Solano et al, 2007;Zhang et al, 2006). Beside, the Korean peninsular consists of many mountains and rivers , which might have caused so diverged Hynobius subclades in South Korea.…”

Cryptic diversity and biogeographical patterns within the black salamander (Aneides flavipunctatus) complex

“…Endemism in the California floristic province is high, with 71 of the 584 (12 %) vertebrates in the region being endemics [5]. Phylogeographic studies of individual species in this region have often revealed high levels of phylogeographic structure [6][7][8][9] and the presence of cryptic species [10][11][12][13], which suggests that there are even greater levels of biodiversity in the region than previously recognized.…”

“…4a) and climatic conditions connecting the two regions may have been more suitable at that time. The pattern of a trans-valley leak from the Coast Ranges to the central Sierra Nevada across the Central Valley has been observed in many other species including Batrachoseps attenuatus [7], Ensatina eschscholtzii xanthoptica [6], Contia tenuis [10], Lampropeltis zonata [47], and California Turret Spiders [66].…”

Persistent Plethodontid Themes: Species, Phylogenies, and Biogeography

“…For example, Highton (2014) reanalyzed the data from a fragment of the cytochrome b gene published by Martínez-Solano et al (2007) and, ignoring their nuclear data, concluded that Batrachoseps attenuatus was a multispecies complex of ''at least 39 species'' (Highton 2014: 140). This is certainly the extreme in taxonomic splitting to date, and I know of no one else who is willing to delimit species on the basis of small amounts of mtDNA alone.…”