From the mountains to the coast and back again: Ancient biogeography in a radiation of short-range endemic harvestmen from California

Abstract

The harvestmen genus Calicina is represented by 25 short-range endemic species occurring in the western Sierra Nevada, Transverse and Coast Ranges of California. Our principal aim was to reconstruct the temporal and spatial biogeographic history of this arachnid lineage. We inferred a time-calibrated species tree for 21 of 25 described Calicina species using multiple genes and multilocus coalescent-based methods. This species tree was used as a framework for algorithmic biogeographic and divergence time analyses, and a phylogenetic canonical correlation analysis (CCA) was used to examine the relationship between morphological evolution and environmental variables. Species tree and biogeographic analyses indicate that high-elevation Sierran taxa are early-diverging in Calicina, with subsequent biogeographic "criss-crossing" of lineages from the Sierra Nevada to the Coast Ranges, back to the Sierra Nevada, then back to Coast Ranges. In both the Sierra Nevada and Coast Ranges, distantly-related parapatric lineages essentially never occur in sympatry. CCA reveals that in both the Coast Ranges and the Sierra Nevada, distant phylogenetic relatives evolve convergent morphologies. Our evidence shows that Calicina is clearly dispersal-limited, with an ancient biogeographic history that provides unique insight into the complex geologic evolution of California since the mid-Paleogene.

New species in the Sitalcina sura species group (Opiliones, Laniatores, Phalangodidae), with evidence for a biogeographic link between California desert canyons and Arizona sky islands

“…First, the Papadopoulou et al (2010) rates result in date estimates that coincide with important biogeographic events in the region (see Discussion). Second, various temporal analyses conducted by Emata and Hedin (2016) for the California phalangodid genus Calicina also showed that the Papadopoulou et al (2010) rate provided biologically realistic dates for a California taxon, while slower rates suggested unrealistically old divergence dates. Finally, we note that recent studies of Sclerobunus using whole genome SNP data (Derkarabetian et al 2016) provide younger divergence ages than previously hypothesized in that system, suggesting that the Derkarabetian et al (2010) COI rate may have been underestimated.…”

“…With two newly described species, Sitalcina now includes a dozen species, and we expect future research to uncover additional undescribed taxa. Ultimately, we predict that Sitalcina diversity might approach that observed in the phalangodid genus Calicina , a taxon that includes over 25 short-range endemic species from central and northern California (Ubick and Briggs 1989, Emata and Hedin 2016). …”

“…material 1: Table S2. Primers for protein-coding nuclear genes targeted terminal exon plus associated 3’ untranslated regions (3’-UTRs), and were developed by comparing transcriptomes of Sitalcina lobata (Hedin et al 2012) to the phalangodid taxon Texella bifurcata (Briggs, 1968) (SRA numbers reported in Emata and Hedin 2016). Both transcriptomes were generated using Illumina short-read technology, and assembled using Trinity software (Grabherr et al 2011).…”

“…In California there are about 70 described phalangodid species, and this number has been growing with further sampling and use of SEM studies of morphology. Most of the described species have very small geographic distributions, and deserve more evolutionary, biogeographic, and conservation interest than currently afforded (Ubick and Briggs 2008, Emata and Hedin 2016). …”

“…Because of apparent limited dispersal abilities and microhabitat specificity, extreme population genetic structuring and divergence can be expected in Sitalcina , as is observed in other low vagility Laniatores (e.g., Thomas and Hedin 2008, Hedin and Thomas 2010, Derkarabetian et al 2011, Starrett et al 2016, Emata and Hedin 2016). As such, some currently described species with naturally fragmented distributions (e.g., Sitalcina peacheyi on isolated mountaintops and in caves) may actually comprise multiple cryptic species.…”