How do diet and body mass drive reproductive strategies in mammals?

Larger body size tends to lead to lower reproductive rates in mammals, but we do not understand how diet impacts this relationship. Reproductive strategies vary from K-selected (producing few offspring with extensive parental care) to r-selected (producing many offspring with little parental care). Here, we investigate how diet and body size impact the reproductive strategies of mammals within a phylogenetic framework using an index for reproductive strategy. For all diet categories we find larger mammals to be more K-selected. This relationship is significant for herbivores and omnivores, but not for carnivores, although the relationship for carnivores is comparable to that of herbivores and omnivores. The relationship is non-linear in carnivores and may be a consequence of differences between insect and vertebrate predators. Ultimately, the trend of more K-selected strategies with larger body size holds true for herbivores and omnivores, but different trajectories exist for carnivores depending on diet.