Data from: Linking micro- and macroevolutionary perspectives to evaluate the role of Quaternary sea-level oscillations in island diversification

With shifts in island area, isolation, and cycles of island
fusion-fission, the role of Quaternary sea-level oscillations as drivers
of diversification is complex and not well understood. Here we conduct
parallel comparisons of population and species divergence between two
island areas of equivalent size that have been affected differently by
sea-level oscillations, with the aim to understand the micro- and
macroevolutionary dynamics associated with sea-level change. Using
genome-wide datasets for a clade of seven Amphiacusta ground cricket
species endemic to the Puerto Rico Bank (PRB), we found consistently
deeper interspecific divergences and higher population differentiation
across the unfragmented Western PRB, in comparison to the currently
fragmented Eastern PRB that has experienced extreme changes in island area
and connectivity during the Quaternary. We evaluate alternative hypotheses
related to the microevolutionary processes (population splitting,
extinction and merging) that regulate the frequency of completed
speciation across the PRB. Our results suggest that under certain
combinations of archipelago characteristics and taxon traits the repeated
changes in island area and connectivity may create an opposite effect to
the hypothesized “species pump” action of oscillating sea levels. Our
study highlights how a microevolutionary perspective can complement
current macroecological work on the Quaternary dynamics of island
biodiversity.