Repeated feeding guild evolution: the impact of competition on diversification

Abstract

Adaptive zones are defined as ecological opportunities for lineages to diversify. Cucujoid beetles provide a unique system to investigate adaptive zones, specifically the interplay between factors that may predict diversity and mechanisms such as competition that may limit diversification. Using a taxon-rich, time -calibrated phylogeny of cucujoid beetles, we report clade ages in conjunction with estimated ages for major shifts in feeding ecology within this group. With these ages, we calculate the delay in time-to-colonization of food resources compared with the extant diversity of each group. We uncovered a pattern of increased lineage diversity specifically with shifts to novel food resources likely devoid of competition from other cucujoid beetles. Neither diversity of the food resource, age of the food resource, or age of the beetle lineage were able to predict species diversity of these groups. Our results provide evidence that shifting to a resource first is a strong predictor of extant diversity.