title: Determinants of bird species richness, endemism, and island network roles in Wallacea and the West Indies: is geography sufficient or does current and historical climate matter?
abstract: Island biogeography has greatly contributed to our understanding of the processes determining species' distributions. Previous research has focused on the effects of island geography (i.e., island area, elevation, and isolation) and current climate as drivers of island species richness and endemism. Here, we evaluate the potential additional effects of historical climate on breeding land bird richness and endemism in Wallacea and the West Indies. Furthermore, on the basis of species distributions, we identify island biogeographical network roles and examine their association with geography, current and historical climate, and bird richness/endemism. We found that island geography, especially island area but also isolation and elevation, largely explained the variation in island species richness and endemism. Current and historical climate only added marginally to our understanding of the distribution of species on islands, and this was idiosyncratic to each archipelago. In the West Indies, endemic richness was slightly reduced on islands with historically unstable climates; weak support for the opposite was found in Wallacea. In both archipelagos, large islands with many endemics and situated far from other large islands had high importance for the linkage within modules, indicating that these islands potentially act as speciation pumps and source islands for surrounding smaller islands within the module and, thus, define the biogeographical modules. Large islands situated far from the mainland and/or with a high number of nonendemics acted as links between modules. Additionally, in Wallacea, but not in the West Indies, climatically unstable islands tended to interlink biogeographical modules. The weak and idiosyncratic effect of historical climate on island richness, endemism, and network roles indicates that historical climate had little effects on extinction-immigration dynamics. This is in contrast to the strong effect of historical climate observed on the mainland, possibly because surrounding oceans buffer against strong climate oscillations and because geography is a strong determinant of island richness, endemism and network roles.
authors.affiliation: Center for Macroecology, Evolution and Climate, Natural History Museum of Denmark, University of Copenhagen Universitetsparken 15, DK-2100, Copenhagen Ø, Denmark ; Conservation Science Group, Department of Zoology, University of Cambridge Downing Street, Cambridge, CB2 3EJ, UK.
authors.forename: Bo
authors.initials: B
authors.lastname: Dalsgaard
authors.affiliation: Department of Biological Sciences, Aarhus University Ny Munkegade 114, DK-8000, Aarhus C, Denmark ; Plant Phenology and Seed Dispersal Group, Departamento de Botânica, Instituto de Biociências, Universidade Estadual Paulista (UNESP) Avenida 24-A n° 1515, Rio Claro, SP, 13506-900, Brazil.
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Carstensen
authors.affiliation: Center for Macroecology, Evolution and Climate, Natural History Museum of Denmark, University of Copenhagen Universitetsparken 15, DK-2100, Copenhagen Ø, Denmark.
authors.forename: Jon
authors.initials: J
authors.lastname: Fjeldså
authors.affiliation: Center for Macroecology, Evolution and Climate, Natural History Museum of Denmark, University of Copenhagen Universitetsparken 15, DK-2100, Copenhagen Ø, Denmark ; Programa de Pós-Graduacão em Ecologia, Universidade Estadual de Campinas (UNICAMP) Cx. Postal 6109, Campinas, SP, 13083-865, Brazil.
authors.forename: Pietro K
authors.initials: PK
authors.lastname: Maruyama
authors.affiliation: Center for Macroecology, Evolution and Climate, Natural History Museum of Denmark, University of Copenhagen Universitetsparken 15, DK-2100, Copenhagen Ø, Denmark.
authors.forename: Carsten
authors.initials: C
authors.lastname: Rahbek
authors.affiliation: Department of Biological Sciences, Aarhus University Ny Munkegade 114, DK-8000, Aarhus C, Denmark.
authors.forename: Brody
authors.initials: B
authors.lastname: Sandel
authors.affiliation: Center for Macroecology, Evolution and Climate, Natural History Museum of Denmark, University of Copenhagen Universitetsparken 15, DK-2100, Copenhagen Ø, Denmark.
authors.forename: Jesper
authors.initials: J
authors.lastname: Sonne
authors.affiliation: Department of Biological Sciences, Aarhus University Ny Munkegade 114, DK-8000, Aarhus C, Denmark.
authors.forename: Jens-Christian
authors.initials: JC
authors.lastname: Svenning
authors.affiliation: Center for Macroecology, Evolution and Climate, Natural History Museum of Denmark, University of Copenhagen Universitetsparken 15, DK-2100, Copenhagen Ø, Denmark.
authors.forename: Zhiheng
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Conservation Science Group, Department of Zoology, University of Cambridge Downing Street, Cambridge, CB2 3EJ, UK.
authors.forename: William J
authors.initials: WJ
authors.lastname: Sutherland
keywords: Birds; Caribbean; Wallacea; West Indies; current climate; endemism; historical climate; island biogeography; modularity; species richness