Miocene extensional tectonics explain ancient patterns of diversification among turret‐building tarantulas (Aphonopelma mojave group) in the Mojave and Sonoran deserts

Abstract

Aim Phylogeographical studies in the Mojave and Sonoran deserts often find genetic discontinuities that pre-date the Pleistocene. A recent synthesis of phylogeographical data, called the Mojave Assembly Model, provides a hypothesis for the historical assembly of these desert biotas but does not adequately capture the complexity of pre-Pleistocene vicariance events. We tested this model and assessed pre-Pleistocene divergences by exploring the phylogeography of the Aphonopelma mojave group, which is composed of turret-building tarantula species from the Mojave and Sonoran deserts.Location Mojave and Sonoran deserts, south-western USA.Methods We augmented the sampling from a previous study by sequencing mitochondrial DNA (COI) from new material of the A. mojave group. We used phylogenetic and network analyses to identify clades and a molecular clock and lineages-through-time plots (LTT plots) to explore the timing and tempo of diversification. We tested for demographic expansion using neutrality tests and mismatch distributions. Species distribution models (SDMs) were constructed to compare current suitable habitat to that at the Last Glacial Maximum (LGM).Results Phylogenetic, network and molecular-clock analyses identified six major clades that probably diverged during the late Miocene. The rate of diversification appears to have slowed during the Pliocene. Most clades exhibit signals of recent demographic expansion. SDMs predicted that suitable habitat shifted south and to lower elevations during the LGM.Main conclusions Phylogeographical analyses suggest that the A. mojave group experienced a burst of diversification in the late Miocene, followed by population expansions during the Pleistocene. Six major clades with origins in the late Miocene cannot be adequately explained by the Mojave Assembly Model. We propose the novel hypothesis that Miocene extensional tectonics caused populations to diverge in allopatry by producing low-elevation habitat barriers. Geological models, such as kinematic reconstructions, provide an ideal but underutilized framework for testing biogeographical hypotheses in these deserts and the wider Basin and Range Province.

Pre‐Pleistocene geological events shaping diversification and distribution of primitively segmented spiders on East Asian margins

“…While using only maternally inherited mtDNA for population genetic analyses may have potential shortcomings (Edwards & Bensch, ), the lineages evaluated here are phylogenetically strongly supported by multilocus data (Xu et al ., ). MtDNA is also widely used in phylogeographical studies of other spiders with lifestyles comparable to liphistiids (Hamilton et al ., ; Graham et al ., , ).…”

A legacy of geo‐climatic complexity and genetic divergence along the lower Colorado River: Insights from the geological record and 33 desert‐adapted animals

“…Geographically, species vary in the amount of genetic divergence that occurs at the river. There is complete differentiation observed for the turret‐building tarantula ( Aphonopelma prenticei ; Graham, Hendrixson, Hamilton, & Bond, ), round‐tailed ground squirrel ( Xerospermophilus tereticaudus ; Bell, Hafner, Leitner, & Matocq, ) and leopard frogs ( Lithobates onca & L. yavapaiensis ; Oláh‐Hemmings et al, ). In contrast, there is little river‐based differentiation in the desert pocket mouse ( Chaetodipus penicillatus ; Jezkova, Jaeger, Marshall, & Riddle, ), Arizona hairy scorpion ( Hadrurus arizonensis ; Graham, Jaeger, Prendini, & Riddle, ), and bighorn sheep ( Ovis canadensis , Nelson; Buchalski et al, ), among others.…”

“…Many species exhibit divergence associated with the ecological boundary dividing the Mojave and Sonoran deserts (Mojave‐Sonoran “ecotone”). Of studies referencing ecotone divergence (Inman et al, ; Wood, Fisher, & Vandergast, ), most attribute this to the vegetation transition (Devitt, ; Graham et al, ; Jezkova et al, ; Mulcahy, Spaulding, Mendelson, & Brodie, ; Wood et al, ) despite the likelihood of an underlying abiotic control (a proximate mechanism) on the change in plant composition. The Mojave Desert has higher average elevation, a wider range of annual temperatures, and lower annual precipitation compared to the Sonoran Desert (Norris, ).…”

“…Temporally, genetic divergence falls into two diffuse periods (Figure , Table S2). Many studies find late Miocene or Pliocene‐aged divergence attributed to flooding of the Gulf of California and northern marine embayments (Devitt, ; Graham et al, , ), or tectonic activity that generated topography of the Basin and Range province and/or the Colorado Plateau (Douglas, Douglas, Schuett, & Porras, ; Graham et al, ; Jaeger, Riddle, & Bradford, ). Other studies show divergence during Pleistocene or Holocene time attributed to climatic (glacial‐interglacial) processes (Douglas et al, ; Gottscho et al, ; Graham et al, ; Graham, Jaeger, Prendini, & Riddle, ; Jezkova et al, ).…”

Multilocus sequence data reveal dozens of putative cryptic species in a radiation of endemic Californian mygalomorph spiders (Araneae, Mygalomorphae, Nemesiidae)

“…68 In addition to improving our understanding of deeper phyloge-69 netic relationships, DNA sequence data have played a crucial role 70 in uncovering and recognizing species-level diversity in mygalo-71 morphs. Recent genetic studies have revealed ancient but morpho-72 logically cryptic species diversity in various mygalomorph groups 73 (Starrett and Hedin, 2007;Stockman and Bond, 2007;Hedin and 74 Carlson, 2011; Graham et al, 2015). Thus far, most genetic studies 75 have relied principally on one or two fragments of mitochondrial 76 DNA.…”