One omnivory does not rule them all: the importance of dietary differentiation in the diversification of phyllostomid bats

Diet specialization in vertebrates can promote diversification while generalist diets may result in evolutionary dead ends, a phenomenon known as the macroevolutionary sink hypothesis. However, generalism or omnivory is often broadly defined and more complex than a single categorical definition, which can bias the effect of diet on diversification dynamics. Here, we developed a novel metric of diet classification and used diet-dependent diversification models to adequately test how diets relate to diversification in an ecologically and morphologically diverse clade of neotropical bats (Phyllostomidae). Using this diet classification based on 13,394 trophic interactions, we examined how dietary differentiation influenced speciation in 163 species of phyllostomids. We found partial support for the macroevolutionary sink hypothesis, such that fruit- and nectar-based diets result in higher speciation rates than omnivorous and animalivorous diets, but omnivory set the stage for the transition from predominantly animal-based diets to plant-specialized feeding consumption. We discovered that by expanding and subdividing their trophic niches, phyllostomid bats most likely diversified from an omnivorous-animalivorous diet. These results highlight omnivory as a key stage in the evolution of dietary specialization, challenging its traditional role as a macroevolutionary sink and underscoring its importance in the diversification of ecologically diverse lineages like phyllostomid bats.