The effects of archipelago spatial structure on island diversity and endemism: predictions from a spatially-structured neutral model.
Islands are particularly suited to testing hypotheses about the ecological and evolutionary mechanisms underpinning community assembly. Yet the complex spatial arrangements of real island systems have received little attention from both empirical studies and theoretical models. Here, we investigate the extent to which the spatial structure of archipelagos affects species diversity and endemism. We start by proposing a new spatially structured neutral model that explicitly considers archipelago structure, and then investigate its predictions under a diversity of scenarios. Our results suggest that considering the spatial structure of archipelagos is crucial to understanding their diversity and endemism, with structured island systems acting both as "museums" and "cradles" of biodiversity. These dynamics of diversification may change the traditionally expected pattern of decrease in species richness with distance from the mainland, even potentially leading to increasing patterns for taxa with high speciation rates in archipelagos off species-poor continental areas. Our results also predict that, within spatially structured archipelagos, metapopulation dynamics and evolutionary processes can generate higher diversity on islands more centrally placed than at the periphery. We derive from our results a set of theoretical predictions, potentially testable with empirical data.
Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175, Montpellier, France. fanny.gascuel@college-de-france.fr.|Center for Interdisciplinary Research in Biology, CNRS UMR 7241, Collège de France, Paris, France. fanny.gascuel@college-de-france.fr.|Sorbonne Universités, UPMC Univ Paris 06, CNRS UMR 7625, Paris, France. fanny.gascuel@college-de-france.fr.|Institut de Biologie de l'Ecole Normale Supérieure, CNRS UMR 8197, Ecole Normale Supérieure, Paris, France. fanny.gascuel@college-de-france.fr.
Fanny
F
Gascuel
Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175, Montpellier, France.|AgroParistech ENGREF, Paris, France.|Irstea, UR EFNO, F-45290 Nogent-sur-Vernisson, France.
Fabien
F
Laroche
Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175, Montpellier, France.|Department of Zoology, University of Cambridge, Cambridge, United Kingdom.
Anne-Sophie
AS
Bonnet-Lebrun
Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175, Montpellier, France.
Ana S L
AS
Rodrigues
D000818:Animals; D044822:Biodiversity; D049810:Genetic Speciation; D055593:Geological Phenomena; D062312:Islands; D008957:Models, Genetic; D011153:Population / Q000235:genetics; D060047:Reproductive Isolation
Biodiversity; biogeography; neutral model; protracted speciation; spatially explicit model; species richness