Phylogenetic effects on functional traits and life history strategies of Australian freshwater fish

Abstract

Understanding the biogeographic and phylogenetic basis to interspecific differences in species' functional traits is a central goal of evolutionary biology and community ecology. We quantify the extent of phylogenetic influence on functional traits and life-history strategies of Australian freshwater fish to highlight intercontinental differences as a result of Australia's unique biogeographic and evolutionary history. We assembled data on life history, morphological and ecological traits from published sources for 194 Australian freshwater species. Interspecific variation among species could be described by a specialist-generalist gradient of variation in life-history strategies associated with spawning frequency, fecundity and spawning migration. In general, Australian fish showed an affinity for life-history strategies that maximise fitness in hydrologically unpredictable environments. We also observed differences in trait lability between and within life history, morphological and ecological traits where in general morphological and ecological traits were more labile. Our results showed that life-history strategies are relatively evolutionarily labile and species have potentially evolved or colonised in freshwaters frequently and independently allowing them to maximise population performance in a range of environments. In addition, reproductive guild membership showed strong phylogenetic constraint indicating that evolutionary history is an important component influencing the range and distribution of reproductive strategies in extant species assemblages. For Australian freshwater fish, biogeographic and phylogenetic history contribute to broad taxonomic differences in species functional traits, while finer scale ecological processes contribute to interspecific differences in smaller taxonomic units. These results suggest that the lability or phylogenetic relatedness of different functional traits affects their suitability for testing hypothesis surrounding community level responses to environmental change.