Beyond the Last Glacial Maximum: Island endemism is best explained by long‐lasting archipelago configurations

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 using the number of single‐island endemic, multiple‐island endemic and (non‐endemic) native species as a response. 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.

Oscillayers: A dataset for the study of climatic oscillations over Plio‐Pleistocene time‐scales at high spatial‐temporal resolution

“…Other potential applications include, for example, the generation of PalaeoENMs via georeferenced fossils (Myers et al, ); the testing of biodiversity‐related hypotheses about palaeo‐climatic stability in the tropics (e.g. Couvreur et al, ; Kissling et al, ; Rakotoarinivo et al, ); the testing of predictions of the glacial‐sensitive model of island biogeography (Fernández‐Palacios et al, ; Norder et al, ) or the facilitation of landscape connectivity (dispersal corridor) analyses over time in a conservation context (Eberle, Rödder, Beckett, & Ahrens, ; Yu et al, ).…”

Pleistocene extinctions as drivers of biogeographical patterns on the easternmost Canary Islands

“…Although the Plio-Pleistocene transition (c. 2.6 Ma) is formally recognized as the onset of the glacial period, there is general agreement that the "mid-Pleistocene transition" (MPT), starting at around 0.8 Ma, established a new stage of abrupt climatic shifts, with the strengthening and lengthening of the glacial-interglacial cycles (Loulergue et al, 2008;Lowe & Walker, 2015). Pleistocene cycles are thought to have had a profound impact on species distributions and survival rates across islands worldwide (Fernández-Palacios et al, 2016;Norder et al, 2019;Weigelt et al, 2016), and islands close to continental masses, as climatically marginal areas, might have experienced stronger impacts than more isolated climatically milder islands (Hardie & Hutchings, 2010).…”

“…In addition, the levels of genetic and species diversity found within insular lineages (Condamine, Leslie, & Antonelli, 2017;García-Verdugo et al, 2013;Kier et al, 2009) suggest that diversification greatly exceeded extinction over geological time. However, recent studies indicate that Pleistocene climatic oscillations may have locally impacted on the biota of subtropical archipelagos (Norder et al, 2019;Prebble et al, 2016;Weigelt, Steinbauer, Sarmento Cabral, & Kreft, 2016). Thus, it is plausible that background extinction on islands could be related to recent climatic events, in addition to abrupt geological episodes (e.g.…”

Deep segregation in the open ocean: Macaronesia as an evolutionary hotspot for low dispersal marine invertebrates

“…Moreover, Macaronesian islands experience a wide range of climatic conditions and possess a highly diverse marine biota that has experienced dynamic geological and climatic changes over relatively long periods (e.g. Pleistocene glaciations; Fernández‐Palacios, ; Fernández‐Palacios et al, ; Norder et al, ). Because Macaronesian archipelagos have never been connected to the mainland, their biota is the result of dispersal from distant geographic sources and in situ diversification (Fernández‐Palacios et al, ).…”