title: Genetic divergence is decoupled from ecological diversification in the Hawaiian Nesosydne planthoppers.
abstract: Adaptive radiation involves ecological shifts coupled with isolation of gene pools. However, we know little about what drives the initial stages of divergence. We study a system in which ecological diversification is found within a chronologically well-defined geological matrix to provide insight into this enigmatic phase of radiation. We tested the hypothesis that a period of geographic isolation precedes ecological specialization in an adaptive radiation of host-specialized Hawaiian planthoppers. We examined population structure and history using mitochondrial and multiple independent microsatellite loci in a species whose geographic distribution on the island of Hawaii enabled us to observe the chronology of divergence in its very earliest stages. We found that genetic divergence is associated with geographic features but not different plant hosts and that divergence times are very recent and on the same timescales as the dynamic geology of the island. Our results suggest an important role for geography in the dynamics of the early stages of divergence.
authors.affiliation: Department of Environmental Science, Policy and Management, 130 Mulford Hall, University of California, Berkeley, California 94720-3114, USA. krgoodman@berkeley.edu
authors.forename: Kari
authors.initials: K
authors.lastname: Roesch Goodman
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Welter
authors.forename: George K
authors.initials: GK
authors.lastname: Roderick
mesh_terms: D000220:Adaptation, Biological; D000818:Animals; D019659:Asteraceae; D017753:Ecosystem; D051456:Gene Flow; D050259:Genes, Mitochondrial; D049810:Genetic Speciation; D014644:Genetic Variation; D005843:Geography; D006254:Hawaii; D006430:Hemiptera / Q000235:genetics*; D018895:Microsatellite Repeats; D060047:Reproductive Isolation