The radiation of red colobus monkeys (Primates,Colobinae): morphological evolution in a clade of endangered African primates

Red colobus monkeys are a group of African monkeys that include some of the most endangered primate populations. Despite urgently needing to understand the importance of particular populations for preserving the biodiversity of this lineage, their evolutionary relationships remain poorly understood, and their taxonomy is unstable, and often enigmatic. Data on behaviour, ecology, genetics, and morphology are thus strongly needed to address taxonomic issues that are not only relevant for primatologists, but also for conservation biologists. In this study, we investigated the morphological diversity and evolution of red colobus by examining the cranial variation of 369 individuals from most living populations. Crania were measured using a set of 64 anatomical landmarks, and were analysed using geometric morphometric methods for the study of three‐dimensional landmark coordinates. We found significant differences among most of the populations traditionally described on the basis of pelage colour and geographic distribution. However, differences tended to be smaller within biogeographic assemblages, which might be related to mountain refugia during periods of forest contraction in the Pleistocene.We also found a tendency towards large taxonomic distances, which suggested that populations might have originated earlier than has been traditionally thought, a result congruent with a recent molecular phylogenetic analysis. However, the distinctive forms of East African relict populations might be related to an acceleration of morphological evolution in small peripheral isolates, under strong selective pressures. This indicates that small and isolated populations, which are also the most endangered ones, might indeed be unique representatives of the red colobus radiation, and hence contribute to its biodiversity significantly. However, in‐ depth morphological studies of red colobus, particularly those in peripheral populations that tend to be rare in the wild, as well as in museum collections, is hampered by a paucity of data. In these cases, populations might be extinct before primatologists and conservationsts can even appreciate what was lost.     

Primates create seedling growth hotspots through pattern of dung deposition

Primates play important roles in tropical forests through seed dispersal and herbivory. They comprise a large part of the biomass of forest communities and tend to have clumped patterns of defecations (i.e. at favoured food trees or sleeping sites). Therefore, they may also play important roles in accelerating ecosystem nutrient cycling. Here we conduct a controlled growth experiment to quantify the effect of the addition of primate dung on the growth of both light‐demanding and shade‐tolerant seedlings over 1 year in Kibale National Park, Uganda. A mixed model analysis revealed that light‐demanding species were affected by the natural dung treatment and plants with small initial size had accelerated growth, whereas there was no effect on plant growth for shade‐tolerant species. The long‐term implications of increased dung deposition on the local tree community are unclear as shade‐tolerant species may only show an effect over the long‐term and light‐demanding species may only be able to take advantage of the increased growth if subsequently exposed to high light conditions, such as a treefall gap.