Phylogenetic relationships of the new world titi monkeys-Callicebus

Reassessment of current taxonomy and conservation status.

Proposal by Jean P Boubli, School of Environment & Life Sciences 

The last decade has witnessed an unprecedented boom in taxonomical and biogeographical discoveries at levels comparable to those of the mid-18th to late 19th century. Such discoveries include not only small and cryptic species but also large and conspicuous ones such as many large mammals, including primates, elephants, and even a whale to name but a few. This has led some to refer to the present as the ‘New Age’ of discoveries 1. Although part of this increase in species descriptions is the result of greater scrutiny in taxonomical studies and increased use of molecular techniques, the bulk of the discoveries and certainly the most surprising ones have come from an increased number of scientific expeditions to unexplored regions of the world 2. This has been the case of New World primates; nearly one new species has been described per year over the last 20 years. A good proportion of these were found in remote interfluvial areas of the Amazon 3, 4. Ranking highest in numbers of new species discovered is the genus Callicebus with 7 new taxa described since 1990. Callicebus or titis are small (1kg) pair-bonding primates widely distributed throughout the Amazon and Atlantic Rainforest Biomes of South America 5. Current taxonomic arrangement recognizes as many as 30 taxa making titis the most diverse primate group in the New World 5-7. This arrangement however, is still rather unsettled; in particular since most species descriptions have been based solely on external morphological characters. Phylogenetic relationships, times of divergence, phylogeography and the role of different geographical barriers in the speciation process are simply not known. At a time when conservation of endangered species has become public policy in habitat countries like Brazil, a robust taxonomical arrangement and a deeper understanding of the ages and distribution of different lineages is paramount. Thus, the main objective of this project is to test current taxonomic hypothesis for the genus Callicebus and to plot the geographical distribution of the various lineages thus providing solid new data to inform next global conservation assessment for this genus.

The fact that titis are widely distributed throughout the Amazon, with a large number of species replacing each other over the landscape, makes them great models to test hypothesis on mechanism of origins of speciation in the Amazon. In particular the riverine hypothesis 8-10 . Wallace 9 was the first to propose that rivers act as barrier isolating species populations on opposite banks of rivers promoting speciation through vicariance and thus, contributing to the genesis of high species diversity in the tropics. Thus, a second objective of this project is to shed light on the controversial issue of the origins of high species diversity in the Amazon 11.

As a result of two ongoing projects, we have been able to collect tissue samples for genetic analysis from a large number of titi species from across the Amazon. Complementary samples will need to be obtained in museums or genebank. Funding is available for fieldwork through an ongoing NSF grant. Tissue samples for genetic analysis are available as a result of an ongoing project.

In summary, the main objectives of this project are to test current taxonomical and phylogeographical hypothesis of primates of the Genus Callicebus and to test the riverine hypothesis as a possible mechanism for speciation in this primate group. Our results will contribute to our understanding of Amazonia biogeography 11 and we will be able to resolve taxonomical and distributional uncertainties that will better define management units of conservation for these poorly understood species.

References:

• Ceballos, G. & Ehrlich, P.R., 2009. Discoveries of new mammal species and their implications for conservation and ecosystem services. Proceedings of the National Academy of Sciences of the United States of America, 106(10), pp.3841–6.
• Donoghue MJ, & Alverson WS (2000) A new age of discovery. Ann Missouri Botanical Gardens 87:110–126. 3.
• Van Roosmalen, M.G.M., Van Roosmalen, T., Mittermeier, R.A. and Rylands, A.B. 2000. Two new species of marmoset, genus Callithrix Erxleben, 1777 (Callitrichidae, Primates), from the Tapajós/Madeira interfluvium, south Central Amazonia, Brazil. Neotropical Primates 8 (1): 2-19.
• Boubli, J.P., Silva, M. N. F., Amado, M. V., Herbk, T., Pontual, F. B. and Farias, I.. A in press. Taxonomic reassessment of black uakari monkey, Cacajao melanocephalus, Humboldt (1811), with the description of two new species. International Journal of Primatology.
• Veiga, L.M., Wallace, R.B. & Martinez, J. 2008. Callicebus olallae. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. < www.iucnredlist.org >. Downloaded on  17 January 2013
• Hershkovitz, P. 1990. Titis, New World monkeys of the genus Callicebus (Cebidae, Platyrrhini): a preliminary taxonomic review. Fieldiana: Zoology 55: 1-109.
• Van Roosmalen, M. G. M., Van Roosmalen, T. and Mittermeier, R.A. 2002. A taxonomic review of the titi monkeys, genus Callicebus Thomas, 1903, with the description of two new species, Callicebus bernhardi and Callicebus stephennashi, from Brazilian Amazonia. Neotropical Primates 10: 1-52.
• Colwell, R. K. 2000. A barrier runs through it... or maybe just a river. PNAS 97: 13470-13472.
• Wallace, A. R. 1852. Proc Zool Soc (London). 20:107–110.
• Gascon, C., J. R. Malcolm, J. L. Patton, M. N. F. da Silva, J. P. Bogart, S. C. Lougheed, C. A. Peres, S. Neckel, and P. T. Boag. 2000. Riverine barriers and the geographic distribution of Amazonian species. Proceedings of the National Academy of Sciences 97:13672-13677.
• Amazonian speciation: a necessarily complex model. Journal of Biogeography 21: 5-17. 6.

For further information, please contact: j.p.boubli@salford.ac.uk

Read more information on how to apply for a Graduate Teaching Studentship.