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Allometry of behavior and niche differentiation among congeneric African antelopes

Citation

Pringle, Robert et al. (2022), Allometry of behavior and niche differentiation among congeneric African antelopes, Dryad, Dataset, https://doi.org/10.5061/dryad.9ghx3ffks

Abstract

Size-structured differences in resource use stabilize species' coexistence in animal communities, but what behavioral mechanisms underpin these niche differences? Behavior is constrained by morphological and physiological traits that scale allometrically with body size, yet the degree to which behaviors exhibit allometric scaling remains unclear; empirical datasets often encompass broad variation in environmental context and phylogenetic history, which complicates the detection and interpretation of scaling relationships between size and behavior. We studied the movement and foraging behaviors of three sympatric, congeneric spiral-horned antelope species (Tragelaphus spp.) that differ in body mass—bushbuck (Tragelaphus sylvaticus, 26–40 kg), nyala (Tragelaphus angasii, 57–83 kg), and greater kudu (Tragelaphus strepsiceros, 80–142 kg)—in an African savanna ecosystem where (i) food was patchily distributed due to ecosystem engineering by fungus-farming termites and (ii) predation risk was low due to the extirpation of several large carnivores. Because foraging behavior is directly linked to traits that scale allometrically with size (e.g., metabolic rate, locomotion), we hypothesized that habitat use and diet selection would likewise exhibit nonlinear scaling relationships. All three antelope species selected habitats near termitaria, hotspots of abundant, high-quality forage. Experimental removal of forage from termite mounds sharply reduced the use of those mounds by bushbuck, confirming that habitat selection was resource-driven. Strength of selection for termite mounds scaled negatively and nonlinearly with body mass, as did recursion (frequency with which individuals revisited locations), whereas home-range area and mean step length scaled positively and nonlinearly with body mass. All species disproportionately ate mound-associated plant taxa; nonetheless, forage selectivity and dietary composition, richness, and quality all differed among species, reflecting the partitioning of shared food resources. Dietary protein exhibited the theoretically predicted negative allometric relationship with body mass, whereas digestible-energy content scaled positively. Our results demonstrate cryptic size-based separation along spatial and dietary niche axes—despite superficial similarities among species—consistent with the idea that body-size differentiation is driven by selection for divergent resource-acquisition strategies, which in turn underpin coexistence. Foraging and space-use behaviors were nonlinearly related to body mass, supporting the hypothesis that behavior scales allometrically with size. However, explaining the variable functional forms of these relationships is a challenge for future research.

Methods

This dataset comprises multiple data types collected in Gorongosa National Park, Mozambique, from 2014-2016. These include metadata for each GPS-collared antelope and fecal sample; summary data on diet composition, diet quality, and food-plant availability; survey data on overstory plant canopy cover, basal area, and species identity; data on foliar nutrient content of plants growing on and off termite mounds; GPS data for each antelope and random locations used to assess habitat selection at landscape and home-range scales; termite mound coordinates digitized from LiDAR imagery; shapefiles with vegetation and lion-utilization layers; data from the forage-removal experiment; derived data on antelope home ranges, step lengths, site revisitation, and mound densities within home ranges, as used in analyses; Illumina data and unrarefied sequence count tables; and the local reference library used to identify fecal DNA sequences in DNA metabarcoding analyses.

Usage Notes

Please see ReadMe file for additional information on data interpretation and usage. 

Funding

National Science Foundation, Award: IOS-1656527

National Science Foundation, Award: IOS-1656642

National Science Foundation, Award: DEB-1501306

National Science Foundation, Award: DEB-1930820

National Science Foundation, Award: DEB-2026294

National Science Foundation, Award: OIA-2033823

High Meadows Environmental Institute, Princeton University

National Geographic Society, Award: 9291-13

Carr Foundation

Cameron Schrier Foundation

Porter Family Fund for Sustainability Science