Abstract
Identifying factors regulating variation in numbers of individuals among populations across a species' distribution is a fundamental goal in ecology. A common prediction, often referred to as the abundant-centre hypothesis, suggests that abundance is highest near the centre of a species' range. However, because of the primary focus on the geographical position of a population, this framework provides little insight into the environmental factors regulating local abundance. While range-wide variation in population abundance associated with environmental conditions has been investigated in terrestrial species, the relationship between climate and local abundance in freshwater taxa across species' distributions is not well understood. We used GIS-based temperature and precipitation data to determine the relationships between climatic conditions and range-wide variation in local abundance for 19 species of North American freshwater fishes. Climate predicted a portion of the variation in local abundance among populations for 18 species. In addition, the relationship between climatic conditions and local abundance varied among species, which is expected as lineages partition the environment across geographical space. The influence of local habitat quality on species persistence is well documented; however, our results also indicate the importance of climate in regulating population sizes across a species geographical range, even in aquatic taxa.
Highlights
Identification of the contemporary factors regulating local population abundance is a fundamental goal in ecology
Whittaker [1,2] provided formative evidence that variation in abundance within and among species is due to differential responses across habitat gradients, supporting the concept that species respond to environmental conditions based on tolerances to those conditions [3]
Based on principal component scores and loadings, temperature is positively correlated with local abundance in Cyprinella analostoma, L. osseus, L. oculatus, Campostoma oligolepis, Cy. venusta and Etheostoma caeruleum, and negatively correlated with local abundance in E. blennioides, E. olmstedi and Moxostoma erythrurum
Summary
Identification of the contemporary factors regulating local population abundance is a fundamental goal in ecology. Whittaker [1,2] provided formative evidence that variation in abundance within and among species is due to differential responses across habitat gradients, supporting the concept that species respond to environmental conditions based on tolerances to those conditions [3]. Studies of variation in population abundance have generally focused on documenting patterns across the geographical ranges of species A common prediction, often referred to as the abundant-centre.
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