Biodiversity of Grasslands

Grasslands can be surprisingly diverse and contain many charismatic flora and fauna. Plant species are often combined into functional groups. Three major conceptual models: competitors-stress tolerants-ruderals (CSR); the leaf traits, plant height, seed mass (LHS); and R*, used to classify grassland species are described by the author. There are three distinct groups of mammalian herbivores based on the ways that herbivores harbor cellulose degrading microbes: hindgut fermentation, foregut fermentation, and foregut fermentation with rumination. Grasslands have a smaller number of bird species than forested systems, and the bird species that are endemic to grasslands tend to be specialized to open habitat (e.g., large flightless birds). Abundant insects can gathered into feeding groups. Single-celled organisms are important in grassland nutrient cycling and as mutualists and pathogens and are extremely abundant in soil. Soil pH is a strong predictor of bacterial diversity (as in plants), with diversity higher in neutral than in acidic soils.

The Karyotype of the Hoatzin (Opisthocomus hoazin) - A Phylogenetic Enigma of the Neornithes

The hoatzin (Opisthocomus hoazin Müller, 1776) is a folivorous bird, endemic to the Amazonian region. It presents some unique characteristics, including wing claws and foregut fermentation, which make its phylogenetic relationship to other birds difficult to determine. There have been various attempts to place it among the Galliformes, Gruiformes, Musophagiformes, Cuculiformes, and Charadriiformes, but phylogenetic analyses always show low supporting values. Nowadays, the hoatzin is included in the monotypic order Opisthocomiformes, but the relationship of this order to other groups of birds is still unclear. Although its karyotype resembles the typical avian model, fissions of the syntenic groups corresponding to chicken chromosomes 1 and 2 and 2 fusions were found. The presence of 18S rDNA clusters in 2 pairs of microchromosomes is another derived character. Hence, different rearrangements were detected in the karyotype of the hoatzin, indicating it has been derived from the putative ancestral karyotype by the occurrence of fissions and fusions. However, as these rearrangements are not exclusive to O. hoazin, they do not clarify the phylogenetic position of this enigmatic species.

The role of ecological opportunity in shaping disparate diversification trajectories in a bicontinental primate radiation

Exceptional species and phenotypic diversity commonly are attributed to ecological opportunity (EO). The conventional EO model predicts that rates of lineage diversification and phenotypic evolution are elevated early in a radiation only to decline later in response to niche availability. Foregut fermentation is hypothesized to be a key innovation that allowed colobine monkeys (subfamily Colobinae), the only primates with this trait, to successfully colonize folivore adaptive zones unavailable to other herbivorous species. Therefore, diversification rates also are expected to be strongly linked with the evolution of traits related to folivory in these monkeys. Using dated molecular phylogenies and a dataset of feeding morphology, I test predictions of the EO model to evaluate the role of EO conferred by foregut fermentation in shaping the African and Asian colobine radiations. Findings from diversification methods coupled with colobine biogeographic history provide compelling evidence that decreasing availability of new adaptive zones during colonization of Asia together with constraints presented by dietary specialization underlie temporal changes in diversification in the Asian but not African clade. Additionally, departures from the EO model likely reflect iterative diversification events in Asia.

Regurgitation and remastication in the foregut-fermenting proboscis monkey ( Nasalis larvatus )

Although foregut fermentation is often equated with rumination in the literature, functional ruminants (ruminants, camelids) differ fundamentally from non-ruminant foregut fermenters (e.g. macropods, hippos, peccaries). They combine foregut fermentation with a sorting mechanism that allows them to remasticate large particles and clear their foregut quickly of digested particles; thus, they do not only achieve high degrees of particle size reduction but also comparatively high food intakes. Regurgitation and remastication of stomach contents have been described sporadically in several non-ruminant, non-primate herbivores. However, this so-called ‘merycism’ apparently does not occur as consistently as in ruminants. Here, to our knowledge we report, for the first time, regurgitation and remastication in 23 free-ranging individuals of a primate species, the foregut-fermenting proboscis monkey ( Nasalis larvatus ). In one male that was observed continuously during 169 days, the behaviour was observed on 11 different days occurring mostly in the morning, and was associated with significantly higher proportions of daily feeding time than on days when it was not observed. This observation is consistent with the concept that intensified mastication allows higher food intake without compromising digestive efficiency, and represents an expansion of the known physiological primate repertoire that converges with a strategy usually associated with ruminants only.

Comparative protein and fibre degradation measured in situ in the caecum of ponies and in the rumen of steers

Previous work has shown that equids generally have lower apparent digestibilities in vivo compared to ruminants. This observation may be due to either; (1) higher rates of passage through the digestive tract of equids compared to ruminants; (2) less opportunity for absorption of microbial digestion end products following hindgut fermentation in equids compared to foregut fermentation in ruminants; or (3) to caecal and colonic micro-organisms in equids being less efficient at feed constituent degradation compared to ruminal micro-organisms. To test this latter possibility, this experiment examines the hypothesis that feed constituents will be degraded to a similar extent when exposed to either an equid hindgut or a ruminal foregut microflora for the same time periods.