Extinction order affects community composition under strong competition and asymmetric species interactions

Abstract

Extinction is a fundamental process impacting how community compositions change though time. Despite this, relatively few studies have examined how the order of species loss in multispecies extinction sequences can differentially impact the composition of the resulting disassembled community, known as an inverse priority effect. Here, we investigate the prevalence and predictors of inverse priority effects across a range of ecological contexts. First, we extend previous theory by deriving all possible cases of inverse priority effects in three-species Lotka-Volterra systems of coexisting competitors with equal intrinsic growth rates. We show that communities with strong, asymmetric competitive interactions are more likely to exhibit inverse priority effects. We then use a random matrix approach to demonstrate that inverse priority effects become more prevalent in more speciose communities and vary with the length of the extinction sequence. Furthermore, in speciose communities, inverse priority effects become increasingly likely with less facilitative or more competitive average interspecific interactions. Together, our results suggest that inverse priority effects are likely common in species-rich communities, particularly those with strong competition and asymmetric species interactions, warranting further theoretical and empirical investigation.