The eternal frontier: an ecological history of north america and it's people

The eternal frontier: an ecological history of north america and it's people full#

found that there were 14 grass species and a forb species upon which these two competitors were niche differentiated, with 10 of these plant species mainly eaten by GrevyвЂ™s zebra and 5 mainly eaten by the plains zebra. For example, the plains zebra and GrevyвЂ™s zebra both mainly eat grass and thus would seem to be strong competitors. ( 4) suggests that the performance of a given herbivore species depends not on how much вЂњforageвЂќ a grassland or savanna may contain but on the actual abundances of those particular plant species on which that herbivore specializes. Why is this so important? The work of Kartzinel et al. ( 4) have provided the finest-resolution evidence to date demonstrating that each large African herbivore species consumes a suite of plant species different from the suite consumed by other cooccurring herbivore species. This dietary niche differentiation can explain the stable coexistence of these competing species.ДЄn earlier study that used carbon isotopes in feces was able to quantify abundances of two major groups of plants, grasses, and browse, and showed that many (but not all) herbivore species were separated along a gradient defined by the ratio of these two plant groups ( 5). They found surprisingly strong dietary differences among these herbivore species. DNA metabarcoding allowed them to quantify the relative dietary abundances of about 100 different plant species or genera, thus demonstrating the efficacy of this approach for coexisting mammals. To determine diets of each species, they obtained from 27 to 52 fecal samples per species during a single season. ( 4) extracted DNA from the feces of seven large African herbivores-the African elephant, impala, two species of zebra, buffalo, Boran cattle, and dik-dik-within a 150 km 2 portion of Kenyan savanna ( Fig.

The eternal frontier: an ecological history of north america and it's people full#

( 4) provide important insights into foodweb structure and coexistence in one of the few remaining terrestrial foodwebs that still has its full complement of large mammals. By using these high-throughput techniques on fecal samples from large African herbivore species to quantify their diets, Kartzinel et al.

The use of next-generation sequencing is emerging as a key tool for quantifying, with fine resolution, the diet composition of consumers ( 3). These issues have limited the ability of ecologists to understand how foodwebs are structured, how so many interacting species can coexist, and how the patterning and strengths of these linkages determine the stability of foodwebs ( 2). However, it has been difficult to determine consumer diets across seasons, individuals, and space, and especially hard to quantify the strengths of these linkages in all but the simplest foodwebs. These foodwebs contain hundreds to thousands of interacting species, each linked to other species either by feeding on them or by being fed on by them. In the 65 million years since a mass extinction led to the demise of dinosaurs, evolution has generated amazingly diverse and complex foodwebs on each continent ( 1).