The species numbers of the naturally occurring insect faunas of the Hawaiian Islands were examined by regression analyses. Extremely significant positive results were found for regressions of number of species per island against island area and elevation. These probably reflect the increasing heterogeneity (habitat diversity) on larger islands. The number of genera against area also supports this ecological explanation, through reducing the influence of speciation. Analyses of number of species against age were confounded by the reduced area and habitat diversity on the older (eroded) islands. Area is the best predictor of species diversity in the Hawaiian Islands. The number of single-island endemic species, and the species/genus ratio against island age, area, and elevation suggest that speciation is fostered by habitat diversity, speciation opportunity, and complex topography (acting as physical isolating mechanisms). These results support the observation that rates of speciation are explosive on younger islands because these harbor more products of genetic differentiation because of more habitat heterogeneity-diversity acting in concert with relaxed competition and reduced natural selection.

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Annals of the Entomological Society of America
Department of Biology

Peck, S, Wigfull, P. (Patrick), & Nishida, G. (Gordon). (1999). Physical correlates of insular species diversity: The insects of the Hawaiian Islands. Annals of the Entomological Society of America, 92(4), 529–536. doi:10.1093/aesa/92.4.529