Data from: Ring species dynamics in California mygalomorph spiders (Nemesiidae, Calisoga)

Idealized ring species, with approximately continuous gene flow around a
geographic barrier but singular reproductive isolation at a ring terminus,
are rare in nature. A broken ring species model preserves the geographic
setting and fundamental features of an idealized model but accommodates
varying degrees of gene flow restriction over complex landscapes through
evolutionary time. Here we examine broken ring species dynamics in
Calisoga spiders, which like classic Ensatina salamanders, are distributed
around the Central Valley of California. Using nuclear and mitogenomic
data we test key predictions of common ancestry, ring-like biogeography,
biogeographic timing, population connectivity and terminal overlap. We
show that a ring complex of populations shares a single common ancestor,
and from an ancestral area in the Sierra Nevada mountains, two
distributional and phylogenomic arms encircle the Central Valley.
Isolation by distance occurs along these distributional arms, although
gene flow restriction is also evident. Where divergent lineages meet in
the South Coast Ranges we find rare lineage sympatry, without evidence for
nuclear gene flow, and with clear evidence for morphological and
ecological divergence. We discuss general insights provided by broken ring
species, and how such a model could be explored and extended in other
systems and future studies.