Data from: A shift in the host web occupancy of dew‐drop spiders associated with genetic divergence in the Southwest Pacific

Aim We assessed the population genetic structure of the kleptoparasitic
spider Argyrodes bonadea across the Southwestern Pacific
islands. Our aim is to evaluate the impact of overseas distances and, in
particular, the Kerama gap, as potential drivers of genetic
differentiation. If no relationship exists, then we assume dispersal
following adaptive change as alternative non-vicariant mechanism that
generates divergence. Location Southwestern Pacific Islands. Taxon
Argyrodes bonadea. Methods We used mitochondrial Cytochrome Oxidase 1
(CO1) gene sequences and Restriction Site-associated DNA Sequencing
(RAD-seq) for our analyses. Results Two strongly supported lineages, an
Amami-Okinawa Lineage (AOL) and an Austral-Asia Lineage (AAL), correspond
to two separate clades, roughly divided by the Kerama Gap, in phylogenetic
trees estimated here. However, species delimitation led to the
interpretation of only a single species present. The AOL exhibits complex,
geographically structured host web spider species specificity, wherein the
Amami population utilizes Cyrtophora, but AOL samples in Okinawa
associate exclusively with Nephila—and yet all broadly
distributed AAL populations show no evidence of host web spider species
specificity. Main Conclusion The population boundary between AOL and AAL
likely results from local adaptation to novel hosts—instead of isolation
by the Kerama Gap—following long-distance dispersal and range expansion.
Our results suggest kleptoparasitic spiders have the capacity to overcome
permanent deep-sea barriers and colonize distant landmasses. Whereas
peripheral populations (AOL) demonstrate the capacity for specialization
to a single host, which may have contributed to genetic differentiation
and isolation, the broadly distributed AAL persists and has successfully
expanded its geographical range as a host generalist, which may contribute
to ongoing gene flow inferred in this study.