Abstract

There has been a continous debate whether there are fundametal morphophysiological differences in the ingestive apparatus (head, teeth) and the digestive tract between browsing and grazing herbivores. A particular characteristic of this debate appears to be that while there is a wealth of publications on such potential differences, the supposed undelying differences between browse and grass have rarely been analysed quantitatively. In this chapter, we first review the actual state of knowledge on those properties of browse and grass that appear relevant for the ingestive and digestive process, and then deduct hypotheses as to how one would assume that browsers and grazers differ due to these characteristics. We address the methodological issues involved in actually testing these hypotheses, with emphasis on the influence of body mass and phylogenetic descent. Finally, we present a literature compilation of statistical tests of differences between the feeding-types. Although in general, the published tests support many hypothesized differences, there is still both a lack of comparative data, and a lack of analyses with phylogenetic control, on different taxonomic levels. However, the published material appears to indicate that convergent evolutionary adaptations of browsing and grazing herbivores to their diet represent a rewarding area of research.