Species Delimitation and Phylogeography of Aphonopelma hentzi (Araneae, Mygalomorphae, Theraphosidae): Cryptic Diversity in North American Tarantulas

Abstract

BackgroundThe primary objective of this study is to reconstruct the phylogeny of the hentzi species group and sister species in the North American tarantula genus, Aphonopelma, using a set of mitochondrial DNA markers that include the animal “barcoding gene”. An mtDNA genealogy is used to consider questions regarding species boundary delimitation and to evaluate timing of divergence to infer historical biogeographic events that played a role in shaping the present-day diversity and distribution. We aimed to identify potential refugial locations, directionality of range expansion, and test whether A. hentzi post-glacial expansion fit a predicted time frame.Methods and FindingsA Bayesian phylogenetic approach was used to analyze a 2051 base pair (bp) mtDNA data matrix comprising aligned fragments of the gene regions CO1 (1165 bp) and ND1-16S (886 bp). Multiple species delimitation techniques (DNA tree-based methods, a “barcode gap” using percent of pairwise sequence divergence (uncorrected p-distances), and the GMYC method) consistently recognized a number of divergent and genealogically exclusive groups.ConclusionsThe use of numerous species delimitation methods, in concert, provide an effective approach to dissecting species boundaries in this spider group; as well they seem to provide strong evidence for a number of nominal, previously undiscovered, and cryptic species. Our data also indicate that Pleistocene habitat fragmentation and subsequent range expansion events may have shaped contemporary phylogeographic patterns of Aphonopelma diversity in the southwestern United States, particularly for the A. hentzi species group. These findings indicate that future species delimitation approaches need to be analyzed in context of a number of factors, such as the sampling distribution, loci used, biogeographic history, breadth of morphological variation, ecological factors, and behavioral data, to make truly integrative decisions about what constitutes an evolutionary lineage recognized as a “species”.

Species Delimitation and Morphological Divergence in the Scorpion Centruroides vittatus (Say, 1821): Insights from Phylogeography

“…As no clear geographic evidence exists to separate the scorpion populations into geographic regions and mountainous terrain appears to isolate them, we considered the regional groups based upon distinct networks created through the mitochondrial and nuclear haplotype network analyses as robust. In addition, other phylogeographic studies with species in the same geographic region also show similar population structure [53]–[55]. These analyses were conducted with scorpion populations to determine if any evidence of recent expansion and non-neutrality of DNA sequences existed in these regional groups.…”

Taxonomic revision and cladistic analysis of Avicularia Lamarck, 1818 (Araneae, Theraphosidae, Aviculariinae) with description of three new aviculariine genera

“…Thus, it is not a surprise when we note many new species of a previously morphologically analyzed taxon being detected when using molecular approaches (Hedin and Carlson 2011; Hendrixson and Bond 2005; Starret and Hedin 2007). A good example of a cryptic biodiversity discovery was by Hamilton et al (2011), when they studied Aphonopelma genus. It is a widespread and specious taxon that has received little attention and “has been largely reliant upon sparse and sometimes poorly defined morphological data” (Hamilton et al 2011).…”

“…A good example of a cryptic biodiversity discovery was by Hamilton et al (2011), when they studied Aphonopelma genus. It is a widespread and specious taxon that has received little attention and “has been largely reliant upon sparse and sometimes poorly defined morphological data” (Hamilton et al 2011). Avicularia seems to be exactly the same case.…”

“…An accurate assessment of species-level diversity is essential not only to specialists; it plays an important role in studies of ecology and biodiversity and consequently in conservation decisions and policy (Hendrixson and Bond 2005; Hamilton et al 2011) as well as in the suitable species’ exploration for developing new technologies, materials, and ideas to confront environmental, medical, and engineering challenges (Wheeler et al 2012). A more precise taxonomy and the proposal of a strongest phylogenetic hypothesis especially for theraphosid spiders are very urgent since constant habitat destruction and high rate of pet trade are pressing problems for spiders populations (Bond et al 2005; Hamilton et al 2011).…”

“…A more precise taxonomy and the proposal of a strongest phylogenetic hypothesis especially for theraphosid spiders are very urgent since constant habitat destruction and high rate of pet trade are pressing problems for spiders populations (Bond et al 2005; Hamilton et al 2011). …”