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

Abstract

Aim Phylogeographical 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. Location Society Islands, French Polynesia (Pacific Ocean). Methods We 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? Results Most 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 conclusions Much 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.

Evolutionary biogeography of the terrestrial biota of the Marquesas Islands, one of the world's remotest archipelagos

“…Although most examined Marquesas lineages are ultimately of Old World origin, there are New World origin lineages as well ( Bidens , Knope, Morden, Funk, & Fukami, ; shrubs and herbs in the genus Plakothira , Weigend, Gottschling, Hoot, & Ackermann, ; Habronattus jumping spiders, Arnedo & Gillespie, ; Misumenops crab spiders; Garb & Gillespie, ). In this regard, the Marquesas biota is similar to that of the Societies in that most endemic lineages appear to be of Old World origin and most closely related to relatives elsewhere in the tropical Pacific (Hembry & Balukjian, ). The Marquesas appear to have a greater fraction of Old World lineages and a smaller fraction of New World lineages in their biota than does Hawaii (Baldwin & Wagner, ; Cowie & Holland, ).…”

“…Here, I compiled 36 studies examining the phylogenetic relationships of 33 Marquesan taxa (Supporting Information Appendix S1, Figures and ; including Barrabé et al., ; Cibois, Thibault, McCormack, & Pasquet, ; Clarkson, Kelly, Leitch, Knapp, & Chase, ; Ganders, Berbee, & Pirseyedi, ; Howarth, Gustafsson, Baum, & Motley, ; Meyer, Boisselier, Taputuarai, & Florence, ; Wright, Yong, Wichman, Dawson, & Gardner, ), with the aim of determining the distributions of their closest relatives outside the archipelago. I followed the methods of Hembry and Balukjian () and ascertained the “closest relatives” of Marquesan taxa as either those which, together with Marquesan relatives, form a monophyletic group, or the closest sister group to a Marquesas‐endemic clade. In cases where node support values and phylogenetic relationships are unambiguous and useful, I also note the biogeographical distribution of the sister group to the larger clade containing Marquesan taxa and their closest relatives (Supporting Information Appendix S1).…”

“…There is limited evidence for the Marquesas serving as a source area for other archipelagos, but some plant taxa show patterns that may be consistent with this, particularly Metrosideros collina (with regards to Hawaii; Percy et al., ) and Coprosma (with regards to Hawaii and Rapa; Cantley et al., ). In these respects, the evolution of the Marquesas biota is more similar to that of Hawaii, where many endemic radiations are monophyletic and there is limited evidence for Hawaii as a source for other regions (e.g., Wagner & Funk, ; Cowie & Holland, ; but see Appelhans et al., ), compared to the Society Islands, where most endemic “radiations” examined are in fact paraphyletic or polyphyletic (Hembry & Balukjian, ).…”

“…Finally, the sister‐group relationships of the Hawaiian and Society Islands biotas differ. Whereas both archipelagos have frequently been colonized from other tropical Pacific archipelagos (Cowie & Holland, ; Hembry & Balukjian, ; Wagner & Funk, ), Hawaii has also often been colonized from North America or East Asia directly (Baldwin & Wagner, ; Cowie & Holland, ).…”

Full Issue

“…Lee & Holyoak (2017) appear to dispute the different biogeographical histories of the western Leeward Islands and eastern Windward Islands. While it is difficult to draw firm conclusions from an impoverished biological class like birds, Hembry & Balukjian (2016) analysed a wide range of taxa. Their conclusion, that 'the most common phylogeographical division seen in Societies taxa is between the Windward and Leeward Society Islands', supports our assumptions based on a small number of bird species.…”