Comparative phylogeography of two codistributed subgenera of cave crickets (Orthoptera: Rhaphidophoridae: Ceuthophilus spp.)

Abstract

Aim We compare the phylogeographical structure among caves for co‐occurring cave dwelling crickets (Ceuthophilus) in two subgenera Ceuthophilus (Ceuthophilus) (hereafter, called Ceuthophilus) and Ceuthophilus (Geotettix) (hereafter, called Geotettix). In our study area (central Texas), cave‐inhabiting members of the subgenus Ceuthophilus are trogloxenes, roosting in the caves but foraging above ground and occasionally moving between caves, whereas members of the subgenus Geotettix are near‐obligate cave dwellers, which forage inside the caves, and only rarely are found above ground. Differences in potential dispersal ability and ecology provide a framework for understanding their effects on the phylogeographical structure and isolation of populations of cave dwelling organisms. Location Edwards Plateau, Texas, USA. Methods We sequenced 1263 bp of two mitochondrial genes for a total of 309 individual rhaphidophorid cave crickets primarily in two subgenera of Ceuthophilus (Rhaphidophoridae). We reconstructed phylogenetic trees for each subgenus using Bayesian inference and then assessed whether their recent evolutionary history exhibited patterns of geographical structure. Results Both Ceuthophilus and Geotettix exhibited strong geographical structure. Rather than exhibiting the expected lower levels of divergence and genetic structure, the trogloxenes of the subgenus Ceuthophilus show deeper divergences than the more cave‐limited Geotettix taxa. Ceuthophilus has a higher proportion of unique haplotypes than does Geotettix. Mismatch distributions of Ceuthophilus and Geotettix differ, with Ceuthophilus exhibiting a multimodal mismatch distribution and Geotettix exhibiting a unimodal mismatch distribution. Main conclusions Both cave cricket subgenera display strong geographical structuring. However, their phylogenetic trees differed in their geographical orientation, which could be explained by timing of colonization, association with caves and underground connections, and above‐ground landscape or ecological barriers. For Ceuthophilus, the relatively high proportion of unique haplotypes and the multimodal mismatch distribution are consistent with relatively larger population size as compared to Geotettix.

At the confluence of vicariance and dispersal: Phylogeography of cavernicolous springtails (Collembola: Arrhopalitidae, Tomoceridae) codistributed across a geologically complex karst landscape in Illinois and Missouri

“…With cave organisms, the majority of research studies have been limited to single species (e.g., Dörge, Zaenker, Klussmann‐Kolb, & Weigand, ; Faille et al., ) or cryptic species complexes with allopatric distributions (e.g., Gómez et al., ; Rastorgueff, Chevaldonné, Arslan, Verna, & Lejeusne, ). Few studies have incorporated phylogeographic approaches that consider intrinsic differences among codistributed cave‐dwelling species (see Pérez‐Moreno, Balázs, Wilkins, Herczeg, & Bracken‐Grissom, ; Weckstein et al., ).…”

Influence of geomorphology and surface features on the genetic structure of an important trogloxene, the secret cave cricket (Ceuthophilus secretus)

“…Sampling over broader spatial scales, Weckstein et al (2016) found that populations of Ceuthophilus exhibit considerable divergence. Our results suggest that dispersal among C. secretus populations is at least partially tied to the contiguous cave and shelterbearing karst ridges of the region.…”

“…Since most populations of C. secretus on FHMR probably consist of hundreds, if not thousands of individuals, effective population sizes may be large enough, even in the absence of fairly robust levels of gene flow, to require many generations of drift for levels of differentiation to reflect recent isolation events (Whitlock and McCauley 1999). Mitochondrial DNA suggests that effective population sizes of Ceuthophilus might be large (Weckstein et al 2016). The observation that site 5 was more similar to eastern NFHR populations, that are separated by a large inlet of Belton Lake, than to populations co-located on NR, would seem to suggest that Belton Lake is too recent of a landscape feature to have erased pre-existing genetic patterns.…”

“…Weckstein et al (2016) found that genetic divergence was as high or higher among samples of Ceuthophilus, which were trogloxenes, than among Geotettix crickets, which are near-cave obligates. These observations bring into question the importance of surface movements in facilitating gene flow in trogloxenes and the degree to which individual cave populations are genetically isolated.…”

Applying species distribution models to caves and other subterranean habitats

“…During the process of adaptation to a subterranean medium, animals have indeed fine-tuned their physiological tolerance to the stable condition of their habitat, which hampers their dispersal ability via non-subterranean habitats. Accordingly, studies conducted so far have uncovered pronounced genetic structuring and low gene flow -if any -between cave populations (Caccone 1985, Bohonak 1999, Dixon and Zigler 2011, Mammola et al 2015, Weckstein et al 2016. For these reasons, a small calibration area can be approximated for most subterranean species.…”