# Pleistocene island connectivity did not enhance dispersal or impact population size change in Galápagos geckos

## TL;DR

The study found that Pleistocene sea-level changes did not significantly influence the diversification or population size of geckos in the Galápagos Islands.

## Contribution

The study provides new genomic evidence that challenges the hypothesis that Pleistocene island connectivity influenced gecko diversification and population dynamics.

## Key findings

- Galápagos Phyllodactylus diversity stems from three independent dispersal events.
- No correspondence was found between lineage divergence and island connectivity during the Pleistocene.
- Demographic expansions were asynchronous and not linked to island age or species.

## Abstract

Patterns of biodiversity on remote archipelagos are largely shaped by intra-archipelago colonization followed by in situ diversification. Pleistocene sea-level fluctuations purportedly enhanced gene flow among terrestrial organisms by increasing connectivity during periods of lower sea level. Furthermore, changes in sea-level are hypothesized to impact population sizes as a result of fluctuations in island sizes. Here, we used genomic data to test the role of Pleistocene island connectivity on the diversification and demographics of leaf-toed geckos (Phyllodactylus) endemic to the Galápagos. Consistent with previous studies, we found that present diversity of Galápagos Phyllodactylus stems from three independent dispersal events. Contrary to the hypothesis of Pleistocene-driven diversification, we found no correspondence between lineage divergence and island connectivity. Furthermore, we found no evidence of introgression; demographic modelling indicated that all species increased rapidly in effective population size in the period 20–150 ka, and these inferred demographic expansions were largely asynchronous and apparently unassociated with species or island age. Collectively, these results indicate that more complex abiotic and/or biotic factors may better explain the recent demographic history of Phyllodactylus and underscore the need for additional population genomic studies of terrestrial taxa to understand the impact of past climate cycles on Galápagos island communities.