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This topic ranges from the description of the digestive anatomy and physiology and the feeding regime of various species in captivity, over the identification of convergent adaptations in feeding or digestion types, to the interpretation of evolutionary adaptation and niche diversification due to the digestive strategy. Especially because of the evolutionary aspect, studies are not limited to extant (living) animals but also include fossil organisms.
We developed in particular feeding guidelines for giraffes, other wild ruminants, elephants, rhinoceroses, tapirs, and hippopotamus. Additionally, other species such as viscachas (a large rodent) or anteaters are investigated. It is our aim to continually increase the range of species covered. In order to increase the scope of our studies, we have recently included life history parameters (average species longevity) as a measure of husbandry and feeding success.
Whenever an opportunity arises, we document the digestive anatomy of wild animals by the use of dissections, photography, and basic measurements. Our catalogue is continually increasing and is used for teaching as well as – when a certain sample size has reached a critical size – for scientific comparative evaluations.
Using experimental research we generate quantitative data that characterise the digestive physiology of various species, such as food intake, digestibility, ingesta retention time, ingesta particle size, the proportion of bacterial matter in the faeces, the amount of methane produced, etc. These data serve as a precise characterisation of a particular species as well as the basis for comparative evaluations.
Based on comparative evaluations of datasets on the comparative digestive anatomy and physiology the different digestive strategies are compared, their costs and benefits are elucidated, so that they are finally interpreted with respect to their adaptive value. Examples are the comparisons of herbivores along the botanical browser-grazer distinction, the comparison of foregut and hindgut fermenters, that of coprophageous and non-coprophageous hindgut fermenters, that of ruminating and non-ruminating foregut fermenters. In the long run, we aim to step back from the assessment of individual sets of groups or opposites („the ruminants“) to a comprehensive treatment of digestive adaptation. Therefore, birds, reptiles, and even remote vertebrate groups such as the dinosaurs are used as model animals. Apart from our own data, we systematically draw upon the existing scientific literature as a resource.
In this final step, the knowledge gained under Digestive Strategies are linked to current understanding of evolutionary history, to describe the historical sequence and coexistence of species and explain the potential competition between the different digestive strategies.
