Influence of past archipelago configuration on present-day insular biodiversity patterns

Abstract: Aim: To quantify the influence of past archipelago configuration on present-day insular biodiversity patterns, and to compare the role of long-lasting archipelago configurations over the Pleistocene to configurations of short duration such as at the Last Glacial Maximum (LGM) and the present-day. Location: 53 volcanic oceanic islands from 12 archipelagos worldwide - Azores, Canary Islands, Cook Islands, Galápagos, Gulf of Guinea, Hawaii, Madeira, Mascarenes, Pitcairn, Revillagigedo, Samoan Islands, and Tristan da Cunha. Time period: The last 800 Kyr, representing the nine most recent glacial-interglacial cycles. Major taxa studied: Land snails and angiosperms. Methods: Species richness data for land snails and angiosperms were compiled from existing literature and species checklists. We reconstructed archipelago configurations at the following sea-levels: the present-day high interglacial sea-level, the intermediate sea-levels that are representative of the Pleistocene, and the low sea-levels of the LGM. We fitted two alternative linear mixed models for each archipelago configuration on the number of single-island endemic, multiple-island endemic, and native non-endemic species. Model performance was assessed based on the goodness-of-fit of the full model, the variance explained by archipelago configuration, and model parsimony. Results: Single-island endemic richness in both taxonomic groups was best explained by intermediate palaeo-configuration (positively by area change, and negatively by palaeo-connectedness), whereas non-endemic native species richness was poorly explained by palaeo-configuration. Single-island endemic richness was better explained by intermediate archipelago configurations than by the archipelago configurations of the LGM or present-day. Main conclusions: Archipelago configurations at intermediate sea-levels - which are representative of the Pleistocene - have left a stronger imprint on single-island endemic richness patterns on volcanic oceanic islands than extreme archipelago configurations that persisted for only a few thousand years (such as the LGM). In understanding ecological and evolutionary dynamics of insular biota it is essential to consider longer-lasting environmental conditions, rather than extreme situations alone. Category: geoscientificInformation Source: Supplement to: Norder, Sietze Johannes; Proios, Kostas V; Whittaker, Robert J; Alonso, María R; Borges, Paulo A V; Borregaard, Michael K; Cowie, Robert H; Florens, F B Vincent; de Frias Martins, António M; Ibáñez, Miguel; Kissling, W Daniel; de Nascimento, Lea; Otto, Rüdiger; Parent, Christine E; Rigal, François; Warren, Ben H; Fernández-Palacios, José María; van Loon, E Emiel; Triantis, Kostas A; Rijsdijk, Kenneth F (2018): Beyond the Last Glacial Maximum: Island endemism is best explained by long-lasting archipelago configurations. Global Ecology and Biogeography, https://doi.org/10.1111/geb.12835 Supplemental Information: Not Availble Coverage: Not Available