Diel niche variation in mammals associated with expanded trait space

D T C Cox,A S Gardner,K J Gaston

doi:10.1038/s41467-021-22023-4

Abstract

Mammalian life shows huge diversity, but most groups remain nocturnal in their activity pattern. A key unresolved question is whether mammal species that have diversified into different diel niches occupy unique regions of functional trait space. For 5,104 extant mammals we show here that daytime-active species (cathemeral or diurnal) evolved trait combinations along different gradients from those of nocturnal and crepuscular species. Hypervolumes of five major functional traits (body mass, litter size, diet, foraging strata, habitat breadth) reveal that 30% of diurnal trait space is unique, compared to 55% of nocturnal trait space. Almost half of trait space (44%) of species with apparently obligate diel niches is shared with those that can switch, suggesting that more species than currently realised may be somewhat flexible in their activity patterns. Increasingly, conservation measures have focused on protecting functionally unique species; for mammals, protecting functional distinctiveness requires a focus across diel niches.

Highlights

We examined whether mammals that displayed diel flexibility in when they are active occupied a distinct region of trait space, or whether flexibility in activity patterns occurred across a broad range of functional trait combinations
Our results and conclusions were qualitatively similar (1) with and without imputed data (Supplementary Tables 1b, 2b, 5; Supplementary Figs. 3–5), (2) when including the first or the first and second principal components from the diet PCoA (Supplementary Fig. 2), and (3) were robust with respect to the identity of the traits (Supplementary Tables 7 and 8), and (4) when including activity pattern as a sixth trait in the ecological strategy surface. Information on these analyses is provided in Supplementary Methods 3
The position of these gradients is influenced by aerial foraging insectivorous bats, which make up almost a quarter of nocturnal and crepuscular species

Summary

Introduction

3–5), (2) when including the first or the first and second principal components from the diet PCoA (Supplementary Fig. 2), and (3) were robust with respect to the identity of the traits (Supplementary Tables 7 and 8), and (4) when including activity pattern as a sixth trait in the ecological strategy surface. Our results and conclusions were qualitatively similar (1) with and without imputed data Information on these analyses is provided in Supplementary Methods

Methods

Results

Conclusion