Abstract
Ecologists have long desired predictive models that allow inference on population dynamics, where detailed demographic data are unavailable. Integral projection models (IPMs) allow both demographic and phenotypic outcomes at the level of the population to be predicted from the distribution of a functional trait, like body mass. In species where body mass markedly influences demographic rates, as is the rule among mammals, then IPMs provide not only opportunity to assess the population responses to a given environment, but also improve our understanding of the complex interplay between traits and demographic outcomes. Here, we develop a body-mass-based approach to constructing generalized, predictive IPMs for species of ungulates covering a broad range of body size (25-400kg). Despite our best efforts, we found that a reliable and general, functional, trait-based model for ungulates was unattainable even after accounting for among-species variation in both age at first reproduction and litter size. We attribute this to the diversity of reproductive tactics among similar-sized species of ungulates, and to the interplay between density-dependent and environmental factors that shape demographic parameters independent of mass at the local scale. These processes thus drive population dynamics and cannot be ignored. Environmental context generally matters in population ecology, and our study shows this may be the case for functional traits in vertebrate populations.
Highlights
Given the paucity of adequate demographic data for many vertebrates in the wild (Conde et al 2019), there has long been an interest among ecologists for models that allow simulation of population-level outcomes but only require a minimal amount of data
The failure to provide a robust model based on one functional trait, even as structuring population dynamics as body mass in ungulates and for a relatively wellstudied taxonomic group, has some consequences
Much of the recent literature about insight provided through functional traits has pertained to plants, and our work indicates that the use of a functional trait frequently measured in vertebrates may not be generalized
Summary
Given the paucity of adequate demographic data for many vertebrates in the wild (Conde et al 2019), there has long been an interest among ecologists for models that allow simulation of population-level outcomes but only require a minimal amount of data. Population biologists, in particular those working with models structured with age or stage classes, have for some time recognized the possibility of this, and several studies have looked for assessing from minimal demographic data a metric of population growth commonly used in ecology, the r-max value (Pianka 1972, Slade et al 1998). Manuscript received 26 January 2020; revised 18 August 2020; accepted 12 November 2020.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
