"Rise of the continent of the monkeys": an integrated genomic and fossil-based analysis of the adaptive radiation of New World primates

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New World primates live in the tropical regions of Central and South America, and include such well-known and charismatic species as spider monkeys, howler monkeys, marmosets and capuchins. Today, there are more than 170 species known in five families, which collectively exhibit a broad range of different body sizes, diets and activity. Remarkably, all this diversity originated from a single common ancestor that reached South America from Africa 35-45 million years ago, probably by being transported over sea on a raft of vegetation. Why and how did this ancestor give rise to all the varied species that make up modern New World primate radiation? What were the drivers leading to the diversification of the different families? Were abiotic factors like changes in climate, the uplift of the Andes mountains, and the development of the Amazon river, or were biotic factors (competition with other mammals) more important in driving diversification? Can we identify when and why there were changes in body size, diet and activity pattern in different New World primate groups? Our proposed project will attempt to answer these questions. To do so, we will combine two very different, but complementary, types of data: genomic data, which provides detailed information on living species, and fossil data, which provides (often very incomplete) information on past diversity. Previous studies have usually used either genomic data or fossil data, but ours will combine the two, to take advantage of their different strengths and to compensate for each other's weaknesses. Firstly, we will examine the genomes of different New World primate species to see if we can identify genes relating to traits like diet, body size and activity pattern. By doing so, we will be able to infer how these traits have changed through time in the different New World primate groups. Secondly we will produce a new evolutionary tree (phylogeny) of all the living New World primate species, using large amounts of genomic data and sophisticated methods to produce the most complete and accurate phylogeny of the group, and we will use "molecular clocks" to infer divergence times for when different lineages split from one another. With our new phylogeny and divergence times, we will examine how the rate of diversification has varied through time, and whether very high or low rates of diversification coincide with periods of environmental change. We will also identify previously unrecognised species and reassess the taxonomy of all known species. This information will be key to conservation efforts, by helping identify the species most in need of protection to conserve maximum biodiversity. Thirdly, we will use data from the fossil record to model how living and extinct lineages of New World primates have diversified through time. This data can be compared with the pattern of diversification indicated by the phylogeny of living New World primates, to see if they are broadly similar. If they show major differences, this suggests that extinction has played a key role in New World primate evolution. We will also use the fossil record to test the hypothesis that New World primates outcompeted superficially "primate-like" mammals (actually, relatives of modern marsupials) that were already present in South America when the New World primate ancestor arrived from Africa. Our project will massively increase our understanding of New World primate evolution, shed new light on diversification and evolutionary processes in general, and help identify those New World primates most vulnerable to extinction. In doing so our findings will be of interest to a wide range of scientists, including evolutionary biologists, genomicists, ecologists and palaeontologists. Because our project, by rigorously clarifying NWP species numbers and boundaries, our results will also have broader practical utility for conservation practitioners and policy makers in governmental and non-governmental agencies.