SEQUENTIAL RADIATIONS AND PATTERNS OF SPECIATION IN THE HAWAIIAN CRICKET GENUS LAUPALA INFERRED FROM DNA SEQUENCES

The tremendous diversity of endemic Hawaiian crickets is thought to have originated primarily through intraisland radiations, in contrast to an interisland mode of diversification in the native Hawaiian Drosophila. The Hawaiian cricket genus Laupala (family Gryllidae) is one of several native genera of flightless crickets found in rain-forest habitat across the Hawaiian archipelago. I examined the phylogenetic relationships among mitochondrial DNA (mtDNA) sequences sampled from 17 species of Laupala, including the 12S ribosomal RNA (rRNA), transfer RNA (RNA)^val and 16S rRNA regions. The distribution of mtDNA variants suggests that species within Laupala are endemic to single islands. The phylogenetic estimate produced from both maximum likelihood and maximum parsimony supports the hypothesis that speciation in Laupala occurred mainly within islands. The inferred biogeographical history suggests that diversification in Laupala began on Kauai, the oldest rain-forested Hawaiian island. Subsequently, colonization to younger islands in the archipelago resulted in a radiation of considerable phylogenetic diversity. Phylogenetic patterns in mtDNA are not congruent with prior systematic or taxonomic hypotheses. Hypotheses that may explain the conflict between the phylogenetic patterns of mtDNA variation and the species taxonomy are discussed.