Can we use a functional trait to construct a generalized model for ungulate populations?

Ecologists have long desired predictive models that allow inference on population dynamics, where detailed demographic data are unavailable. Integral projection (IPMs) both and phenotypic outcomes at the level of to be predicted from distribution a functional trait, like body mass. In species mass markedly influences rates, as is rule among mammals, then IPMs provide not only opportunity assess responses given environment, but also improve our understanding complex interplay between traits outcomes. Here, we develop body-mass-based approach constructing generalized, for ungulates covering broad range size (25–400 kg). Despite best efforts, found reliable general, functional, trait-based model was unattainable even after accounting among-species variation in age first reproduction litter size. We attribute this diversity reproductive tactics similar-sized ungulates, density-dependent environmental factors shape parameters independent local scale. These processes thus drive dynamics cannot ignored. Environmental context generally matters ecology, study shows may case vertebrate populations.