Life history and ecological trait relationships with imperilment and invasiveness in crayfish

Species’ traits may be useful in understanding patterns of imperilment and invasiveness. Crayfish are both a highly imperiled taxa as well as one that has produced many invasive species. We performed a trait analysis for 77 crayfish from two southeastern U.S.A. states to understand which traits make crayfish prone to imperilment or invasiveness, as well as anticipate which species may face extinction or become invasive in the future. Eight life history and ecological traits were evaluated using principal coordinate analysis (PCoA), with potential interactions and synergisms among traits further examined by classification and regression trees (CART). Generally, invasive and imperiled species grouped together in multivariate space in the PCoA, with invasive crayfish large, high fecundity, habitat generalists found across wide distributions, while imperiled crayfishes were small, low fecundity, habitat specialists with small distributions. CART successfully isolated invasive from non-invasive crayfish through a combination of fecundity (>288 eggs per female) and size (>95 mm maximum size) and identified potential invasive crayfish through misclassification. Imperilment was more difficult to correctly classify, although small range sizes, narrow habitat preferences, and small body size characterized imperiled crayfish. These results should prove useful in the management and conservation of this important freshwater taxa.