Quantifying Differences Between Native and Introduced Species

Introduced species have historically been presumed to be evolutionarily novel and 'different' from native species. Recent studies question these assumptions, however, as the traits and factors promoting successful introduced and native species can be similar. We advocate a novel statistical framework utilizing quantifiable metrics of evolutionary and ecological differences among species to test whether different forces govern the success of native versus introduced species. In two case studies, we show that native and introduced species appear to follow the same 'rules' for becoming abundant. We propose that incorporating quantitative differences in traits and evolutionary history among species might largely account for many perceived effects of geographic origin, leading to more rigorous and general tests of the factors promoting organism success.