Intermittent migration can induce pulses of speciation in a two-island system.

This article investigates how intermittent migration driven by sea-level fluctuations influences speciation and species richness in a neutral two-island model. Using individual-based simulations with cyclic isolation and connection phases modulated by seabed depth and migration probability, the study finds that pulsed migration can induce speciation pulses and transient increases in species richness that do not occur under strict isolation or continuous migration. Results highlight complex, dynamic patterns of diversification dependent on the timing and intensity of migration, supporting hypotheses such as the taxon pulse and species pump, and emphasize the role of neutral microevolutionary processes in out-of-equilibrium populations. The findings underscore the importance of considering temporal variability in migration and dynamic geographic barriers when studying biodiversity patterns, particularly in regions affected by sea-level changes.