Inferring Species Trees from Gene Trees in a Radiation of California Trapdoor Spiders (Araneae, Antrodiaetidae, Aliatypus)

Abstract

BackgroundThe California Floristic Province is a biodiversity hotspot, reflecting a complex geologic history, strong selective gradients, and a heterogeneous landscape. These factors have led to high endemic diversity across many lifeforms within this region, including the richest diversity of mygalomorph spiders (tarantulas, trapdoor spiders, and kin) in North America. The trapdoor spider genus Aliatypus encompasses twelve described species, eleven of which are endemic to California. Several Aliatypus species show disjunct distributional patterns in California (some are found on both sides of the vast Central Valley), and the genus as a whole occupies an impressive variety of habitats.Methodology/Principal FindingsWe collected specimens from 89 populations representing all described species. DNA sequence data were collected from seven gene regions, including two newly developed for spider systematics. Bayesian inference (in individual gene tree and species tree approaches) recovered a general “3 clade” structure for the genus (A. gulosus, californicus group, erebus group), with three other phylogenetically isolated species differing slightly in position across different phylogenetic analyses. Because of extremely high intraspecific divergences in mitochondrial COI sequences, the relatively slowly evolving 28S rRNA gene was found to be more useful than mitochondrial data for identification of morphologically indistinguishable immatures. For multiple species spanning the Central Valley, explicit hypothesis testing suggests a lack of monophyly for regional populations (e.g., western Coast Range populations). Phylogenetic evidence clearly shows that syntopy is restricted to distant phylogenetic relatives, consistent with ecological niche conservatism.Conclusions/SignificanceThis study provides fundamental insight into a radiation of trapdoor spiders found in the biodiversity hotspot of California. Species relationships are clarified and undescribed lineages are discovered, with more geographic sampling likely to lead to additional species diversity. These dispersal-limited taxa provide novel insight into the biogeography and Earth history processes of California.

Crossing the uncrossable: novel trans‐valley biogeographic patterns revealed in the genetic history of low‐dispersal mygalomorph spiders (Antrodiaetidae,Antrodiaetus) from California

“…These include trapdoor spiders ( Aliatypus janus ; Satler et al . ), kingsnakes (Rodriguez‐Robles et al . ) and Emys turtles (Spinks et al .…”

“…Beyond revealing biogeographic patterns, these studies have provided general lessons in evolutionary biology, for example regarding species delimitation (Bond & Stockman ; Wake ), speciation (Pereira & Wake ; Satler et al . ) and the conservation of evolutionary processes (Bond et al . ; Davis et al .…”

Three new species in the harvestmen genus Acuclavella (Opiliones, Dyspnoi, Ischyropsalidoidea), including description of male Acuclavella quattuor Shear, 1986

“…EF-1α has been shown to have phylogenetic utility at two levels (Hedin et al 2010); in the region amplified for Acuclavella , more slowly evolving exons bracket a relatively rapidly evolving intron. The Wnt2 gene region has been used to reconstruct spider phylogenies (e.g., Blackledge et al 2009, Satler et al 2011), but is used here for the first time in Opiliones. PCR primer and amplification conditions are available as a supplementary file (Appendix II - PCR Primer Information).…”

A new species of Illacme Cook & Loomis, 1928 from Sequoia National Park, California, with a world catalog of the Siphonorhinidae (Diplopoda, Siphonophorida)

“…The phylogenetic studies of salamanders indicate a west-to-east pattern, relatively recent in the mid-late Pleistocene. In contrast, the studies of mygalomorphs and diplopods recover an east-to-west directionality of diversification (Satler et al 2011, Marek and Moore 2015). Several of these taxa (e.g., Calicina and Batrachoseps ) have occurred in California since the Eocene, with a “trans-valley” split occurring in the harvestman Calicina during mid-late Miocene (Emata and Hedin 2016).…”