Scale‐dependent effects of niche specialisation: The disconnect between individual and species ranges

Abstract

One of the most general expectations of species range dynamics is that widespread species tend to have broader niches. However, it remains unclear how this relationship is expressed at different levels of biological organisation, which involve potentially distinctive processes operating at different spatial and temporal scales. Here, we show that range sizes of terrestrial non‐volant mammals at the individual and species level show contrasting relationships with two ecological niche dimensions: diet and habitat breadth. While average individual home range size appears to be mainly shaped by the interplay of diet niche breadth and body mass, species geographical range size is primarily related to habitat niche breadth but not to diet niche breadth. Our findings suggest that individual home range size is shaped by the trade‐off between energetic requirements, movement capacity and trophic specialisation, whereas species geographical range size is related to the ability to persist under various environmental conditions.

The Impact of Environmental Factors On The Evolution of Brain Size In Carnivorans

“…A brain that requires less energy would therefore allow carnivorans to settle more easily and sustainably in new environments. Our hypothesis also echoes a recent study which demonstrates that home range size in terrestrial mammals is the result of a trade-off between the ecological specialization of a species and its ability to move, while the geographic distribution is linked to the ability of a species to resist to various environments [97] . Like Huang et al [97] , our result re ects a potential impact of natural selection at two different evolutionary scales: the use of the surrounding environnement by individuals, and the dispersal of species within different habitats and localities.…”

“…This scenario is also supported by studies which show that the risk of extinction is higher in mammals with relatively larger brains [98] . Finally, it is possible that populations with a large geographic distribution may also display higher intra-speci c variability of their EQ [97] . Our analyses do not allow us to speci cally test this phenomenon, but we acknowledge the importance of investigating intra-speci c brain size differences in the future to better understand the evolution of encephalization at different scales and test the strength of our hypothesis.…”

Energetic dissociation of individual and species ranges

“…These patterns are particularly true for small-sized mammals, although results remained unchanged when including all species. We also showed that, as predicted by theoretical work [8,20,22,53,54], the variance in ranges sometimes assigned to body mass [9] was accounted for by metabolic traits, when both mass and metabolic traits are considered explicitly.…”

“…For instance, while competition is an important driver of species distributions at the local scale, it presumably has a limited effect at the global scale ( [4], but see [5]). That has led to fine-and large-scale ecological phenomena being scrutinized either separately [6][7][8] or, when considered together, using disparate explanatory variables with loose connections [9]. A clear example is the question of what underpins organisms' distribution ranges ( [4], but see [10]).…”

“…in reserves) [27,32,33]. The difference between individual and species scales for the energetic limitation suggests a trade-off operating on maintenance costs, resulting in the apparent weak correlation between individual and species range sizes [9]. However, energetic limitations to both ranges have never been considered simultaneously [9].…”