Environmental factors associated with the distribution and range limits of the malaria vector *Anopheles farauti* in Australia

Abstract

Ecological factors associated with the narrow coastal distribution of Anopheles farauti Laveran s.s. were investigated using decision tree software and a recently developed software tool that permits analysis of environmental gradients across distributional boundaries. SigniÞcant variables identiÞed by these procedures were then used to develop ecological niche models that permitted detailedÑand improvedÑpredictions of the speciesÕ overall distribution. These methods identiÞed seven climatic factors (four of temperature factors and three atmospheric moisture factors) from among 40 environmental variables related to the range of this species. In addition, the gradient-analysis tool identiÞed elevation as being particularly important. The distributional hypothesis predicted using ecological niche modeling of these factors included all of the record sites from which An. farauti s.s. was collected in northern Australia and successfully reconstructed its narrow limitation to coastal areas. Omission of elevation from analyses resulted in unrealistic predictions of potential distributional areas 100 km inland, where the species has not been found.