Global climate change and accuracy of prediction of species’ geographical ranges: establishment success of introduced ladybirds (Coccinellidae, Chilocorus spp.) worldwide
AimPredictions of how the geographical ranges of species change implicitly assume that range can be determined without invoking climate change. The aim here was to determine how accurate predictions of range change might be before entertaining global climatic change.
MethodsAll the documented global biological control translocations of ladybirds (Coccinellidae: Chilocorus spp.) were analysed with the ecoclimatic program, CLIMEX. This program determines species distributions in relation to climate, and can be used to express the favourableness of different localities for a species. CLIMEX is also a useful exploratory tool for determining the likelihood of establishment of species introduced from one area to another.
ResultsPredictive models were developed based on the likelihood of establishment of fifteen Chilocorus spp. relative to their physiological characteristics and climatic tolerances. This likelihood was compared with actual establishment with a resultant range of 0% accuracy to 100% accuracy. Only four (26.7%) species climatic tolerances could the predicted with 100% certainty. The general lack of accurate prediction was because climate is not always the overriding feature determining whether a species will establish or not. Other determinants, such as localized response to microclimate, phenology, host type and availability, presence of natural enemies and hibernation sites play a varying role over and above climate in determining whether a species will establish at a new locality.
Main conclusionsThis study shows that even in the absence of climate change, range cannot always be determined, which means that most predictions of range change with climate change are likely to be wrong.
Document Type: Research Article
Affiliations: Invertebrate Conservation Research Centre, University of Natal, P/Bag X01, Scottsville 3209, South Africa
Publication date: July 1, 1999