Molecular phylogeography of the Society Islands (Tahiti; South Pacific) reveals departures from hotspot archipelago models

Abstract

AbstractAimPhylogeographical and modelling studies have suggested that the biotas of oceanic hotspot archipelagos (such as the Hawaiian, Canary and Galápagos islands) diversify in parallel with the formation of the islands on which they live. Here, we review the phylogeography of the native terrestrial biota of the Society Islands, an archipelago formed < 4.6 Ma, to test this model.LocationSociety Islands, French Polynesia (Pacific Ocean).MethodsWe reviewed 49 phylogenetic and phylogeographical studies incorporating Society Island terrestrial animal and plant taxa. We ask: (1) Where are the sister groups of Societies lineages distributed? (2) Are Societies‐endemic ‘radiations’ monophyletic or polyphyletic? (3) What between‐island barriers are seen in the phylogeography of Societies taxa? (4) What within‐island barriers are seen in the phylogeography of Societies taxa? (5) How old is the Societies biota?ResultsMost Societies lineages are closely related to those in other tropical Pacific archipelagos, particularly the Cook, Austral and Marquesas Islands (< 2000 km distant). More genera show strong evidence for polyphyly (13 genera) than for monophyly (4 genera) in the Society Islands. The most common within‐archipelago phylogeographical barrier corresponds to the straits (150 km) between the Windward Society and Leeward Society Islands. Only a few groups, primarily species‐rich invertebrate radiations, show divergence among or within islands. Published divergence time estimates suggest that much of the Societies biota may be much younger than the age of the archipelago.Main conclusionsMuch of the Societies biota does not appear to have diversified in parallel with the formation of the archipelago, differing from ‘progression rule’ and general dynamic models for the diversification of oceanic archipelago biotas. Rather, many Societies ‘radiations’ may have been assembled via repeated, independent colonizations, which may have entailed extensive macroevolutionary turnover of colonizing lineages. These patterns have implications for the biogeography of other Pacific hotspot archipelagos.