Linking micro‐ and macroevolutionary perspectives to evaluate the role of Quaternary sea‐level oscillations in island diversification

Abstract

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.

Beyond the Last Glacial Maximum: Island endemism is best explained by long‐lasting archipelago configurations

“…Heaney et al, ). This agrees with a recent study on the Puerto Rico Bank where repeated connectedness and fragmentation impeded divergence and speciation of ground crickets (Papadopoulou & Knowles, ). Alternatively, elevated biotic interchange following climatic fluctuations and geographical rearrangements over the Pleistocene might have resulted in local extinctions (Vermeij, ).…”

Testing main Amazonian rivers as barriers across time and space within widespread taxa

“…Admittedly, with any genetic signature of this older history overridden by the divergence in allopatry that dates to a relative recent past (Table ), it is not clear why earlier dispersal events were not associated with long‐term isolation, especially considering the persistence of isolation over the tens to hundreds of thousands of years documented here in both species, and even longer in some cases within D. leucophyllatus . Given the analysed taxa are widespread and common where they occur, it is unlikely that local extinctions (at least at the geographic scale examined here; Figure ), are driving colonization dynamics (see Papadopoulou & Knowles, ). Instead, it is more likely that abiotic factors associated with shifting river physiography (e.g.…”

The comparative biogeography of Philippine geckos challenges predictions from a paradigm of climate‐driven vicariant diversification across an island archipelago

“…This model can be relevant to a diversity of structured environments, including deep ocean (Ricklefs and Bermingham ; Brown et al. ; Papadopoulou and Knowles ) and coastal (Papadopoulou and Knowles ; Senczuk et al. ) islands, and mountain tops (i.e., “sky” islands; Knowles , ; McCormack et al.…”