Trophic ecology of large herbivores in a reassembling African ecosystem

Abstract

1. Megafauna assemblages have declined or disappeared throughout much of the world, and many efforts are underway to restore them. Understanding the trophic ecology of such reassembling systems is necessary for predicting recovery dynamics, guiding management, and testing general theory. Yet, there are few studies of recovering large-mammal communities, and fewer still that have characterized food-web structure with high taxonomic resolution.2. In Gorongosa National Park, large herbivores have rebounded from near-extirpation following the Mozambican Civil War (1977)(1978)(1979)(1980)(1981)(1982)(1983)(1984)(1985)(1986)(1987)(1988)(1989)(1990)(1991)(1992). However, contemporary community structure differs radically from the prewar baseline: medium-sized ungulates now outnumber larger bodied species, and several apex carnivores remain locally extinct.3. We used DNA metabarcoding to quantify diet composition of Gorongosa's 14 most abundant large-mammal populations. We tested five hypotheses: (i) the most abundant populations exhibit greatest individual-level dietary variability; (ii) these populations also have the greatest total niche width (dietary diversity); (iii) interspecific niche overlap is high, with the diets of less-abundant species nested within those of more-abundant species; (iv) partitioning of forage species is stronger in more structurally heterogeneous habitats; and (v) selectivity for plant taxa converges within guilds and digestive types, but diverges across them. Abundant (and narrow-mouthed) populations exhibited higher among-individualdietary variation, but not necessarily the greatest dietary diversity. Interspecific dietary overlap was high, especially among grazers and in structurally homogenous habitat, whereas niche separation was more pronounced among browsers and in heterogeneous habitat. Patterns of selectivity were similar for ruminantsgrazers and browsers alike-but differed between ruminants and non-ruminants. 5.Synthesis. The structure of this recovering food web was consistent with several hypotheses predicated on competition, habitat complexity, and herbivore traits, but it differed from patterns observed in more intact assemblages. We propose that intraspecific competition in the fastest-recovering populations has promoted individual variation and a more nested food web, wherein rare species use subsets of foods eaten by abundant species, and that this scenario is reinforced by weak 1356 | Journal of Ecology PANSU et Al.

Metabarcoding reveals diet diversity in an ungulate community in Thailand

“…However, wild pig and muntjac were poorly sampled in this study and any definitive conclusion about their diet is not possible. Our data do support herbivore community studies that indicate feeding mode, and not body size or phylogeny determine niche breadth (Bagchi et al, ; Kartzinel et al, ; Lintulawkso & Kovarovic, ; Pansu et al, ).…”

“…Multiple studies in African systems have demonstrated the complexity of foraging strategies among ungulate communities, with species arrayed along a continuum that reflects differences in body size (Cummings & Cummings, ; Fritz & Loison, ; Hopcraft et al, ), morphology (Pansu et al, ) phylogeny (Pérez‐Barbería, Gordon, & Nores, ), and behavior (Owen‐Smith, ). Kartzinel et al () found body size a coarse indicator of grass versus woody species consumption, but pairs of similar body‐size species differed in the specific plant species consumed.…”

Determinants of elephant foraging behaviour in a coupled human‐natural system: Is brown the new green?

“…To test the prediction that digestible energy and protein content would be significantly higher in cultivated crop plants than in natural‐forage species consumed by elephants within the Park (P3), we first quantified diet composition of elephants using DNA metabarcoding (Kartzinel et al., ; Pansu et al., ) of 21 fresh faecal samples collected inside GNP during the dry season (June–August) of 2016. We collected samples during immobilizations and also opportunistically after observing elephants defecating and then waiting for them to leave the area.…”

“…Sample collection and processing followed protocols described by Pansu et al. (), and a detailed description of the metabarcoding protocol and analyses is provided in Supporting information Appendix C.…”

DNA metabarcoding in diet studies: Unveiling ecological aspects in aquatic and terrestrial ecosystems

“…Importantly, the results obtained so far provide substantial knowledge toward effective conservation planning and management, by identifying the impacts of introduced species, both revealing competition with native fauna (Brown et al, ; Egeter, Bishop, & Robertson, ; Robeson II et al, ; Zarzoso‐Lacoste et al, ) and uncovering the importance of introduced plant species to the diet of endangered species (Ando et al, ). There have also been some studies focusing on the diets of reintroduced or recovering populations (Kowalczyk et al, ; Pansu et al, ; Pinho et al, ) and on the effects of hunting in niche partitioning between both herbivores (Pansu et al, ) and carnivores (Smith et al, ). Additionally, the effects of pollution have been addressed twice, with light pollution having species‐specific effects on bats' feeding habits (Cravens et al, ) and trace metal pollution modulating food preferences of the wood mouse Apodemus sylvaticus (Ozaki et al, ).…”