title: Predicting Where a Radiation Will Occur: Acoustic and Molecular Surveys Reveal Overlooked Diversity in Indian Ocean Island Crickets (Mogoplistinae: Ornebius).
abstract: Recent theory suggests that the geographic location of island radiations (local accumulation of species diversity due to cladogenesis) can be predicted based on island area and isolation. Crickets are a suitable group for testing these predictions, as they show both the ability to reach some of the most isolated islands in the world, and to speciate at small spatial scales. Despite substantial song variation between closely related species in many island cricket lineages worldwide, to date this characteristic has not received attention in the western Indian Ocean islands; existing species descriptions are based on morphology alone. Here we use a combination of acoustics and DNA sequencing to survey these islands for Ornebius crickets. We uncover a small but previously unknown radiation in the Mascarenes, constituting a three-fold increase in the Ornebius species diversity of this archipelago (from two to six species). A further new species is detected in the Comoros. Although double archipelago colonisation is the best explanation for species diversity in the Seychelles, in situ cladogenesis is the best explanation for the six species in the Mascarenes and two species of the Comoros. Whether the radiation of Mascarene Ornebius results from intra- or purely inter- island speciation cannot be determined on the basis of the phylogenetic data alone. However, the existence of genetic, song and ecological divergence at the intra-island scale is suggestive of an intra-island speciation scenario in which ecological and mating traits diverge hand-in-hand. Our results suggest that the geographic location of Ornebius radiations is partially but not fully explained by island area and isolation. A notable anomaly is Madagascar, where our surveys are consistent with existing accounts in finding no Ornebius species present. Possible explanations are discussed, invoking ecological differences between species and differences in environmental history between islands.
authors.affiliation: Université de La Réunion, UMR PVBMT, 7 chemin de l'IRAT, Ligne Paradis, 97410 Saint Pierre, Réunion, France.|Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, 8008, Zurich, Switzerland.
authors.forename: Ben H
authors.initials: BH
authors.lastname: Warren
authors.affiliation: Université de La Réunion, UMR PVBMT, 7 chemin de l'IRAT, Ligne Paradis, 97410 Saint Pierre, Réunion, France.
authors.forename: Rémy
authors.initials: R
authors.lastname: Baudin
authors.affiliation: Cirad, UMR PVBMT, 7 chemin de l'IRAT, Ligne Paradis, 97410 Saint Pierre, Réunion, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Franck
authors.affiliation: UPR 3212 CNRS, Université de Strasbourg, 5 rue Blaise Pascal, 67084 Strasbourg, cedex 3, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Hugel
authors.affiliation: Université de La Réunion, UMR PVBMT, 7 chemin de l'IRAT, Ligne Paradis, 97410 Saint Pierre, Réunion, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Strasberg
mesh_terms: D000819:Animal Communication; D063147:Animal Distribution; D000818:Animals; D005260:Female; D017344:Genes, Insect; D050259:Genes, Mitochondrial; D049810:Genetic Speciation; D014644:Genetic Variation; D006135:Gryllidae / Q000502:physiology*; D019156:Indian Ocean; D007195:Indian Ocean Islands; D008297:Male; D058885:Multilocus Sequence Typing; D010802:Phylogeny