Repeated feeding guild evolution: the impact of competition on diversification in cucujoid beetles

Adaptive-zones can be formed by shifts in feeding behavior that provide ecological opportunities for a lineage and lead to diversification. These shifts also likely result in additional pressures such as predation, competition, novel resource defense mechanisms, etc. Cucujoid beetles provide a unique system to investigate the interplay between the increases in diversity resulting from adaptive-zones and potential decreases from negative mechanisms. Using a taxon-rich, time calibrated phylogeny of Cucujoidea, with all major lineages and feeding behaviors included, we are able to report clade ages, estimate ages for major shifts in feeding ecology, and calculate the delay in time to colonization of food resources. With these age estimates we were also able to compare the extant diversity of each group and uncover a pattern of increased diversity, not with every feeding shift, but specifically with shifts to food resources devoid of competition. We provide evidence that shifting to a resource first is a strong predictor of extant diversity and that 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.