Kivisild Toomas

[Centurion]

Telephone: +44 (0)1223 764703
Fax: +44 (0)1223 764710
E-mail: t.kivisild@human-evol.cam.ac.uk

POSITIONS HELD
University Lecturer in Human Evolutionary Genetics


RESEARCH INTERESTS

My research interests include most generally human evolution and evolutionary population genetics, with a particular focus on questions relating global genetic population structure with evolutionary processes such as selection, drift, migrations and admixture.

One of the major topics of my research has been genetic diversity in South Asia and its role in the settlement of Eurasia. Have the diverse populations of India emerged as a result of admixture of East and West Eurasians as the language distributions would suggest? The study of mtDNA and Y chromosome variation has revealed that, instead, a large majority of the genetic lineages present in India – both among the caste and tribal groups – are unique to the subcontinent and likely trace their common ancestry with West and East Eurasian lineages back to the single and rapid out of Africa migration approximately 40 to 60 thousand years back with relatively minor element of later admixture across subcontinental borders.

Besides migration and genetic drift natural selection has played an obvious role in shaping human genetic diversity. However, it is not clear whether the mutations occurring for example in mitochondrial DNA encoded oxphos genes have directly adaptive properties in response to environment. A theory of climatic adaptation of mitochondrial DNA haplogroups has claimed some support through studies revealing higher proportion of non-synonymous substitutions in Arctic populations. This theory states that non-synonymous defects in genes responsible for ATP generation would generate extra heat which would be beneficial in populations living in cold environment. Studies by us and our colleagues have showed, however, that the higher proportion of non-synonymous changes in mtDNA haplogroups spread in the Arctic is not unique but a general feature of young branches of the mtDNA tree. Young haplogroups not only in the Artic but also in Africa and Southeast Asia bear the excess of non-synonymous mutations because, most likely, purifying selection has not yet had time enough to eliminate all the slightly deleterious substitutions.

Even though genes encoded by mitochondrial DNA do not determine phenotypes like body height or pigmentation, its phylogeography can be used to assess whether darkly pigmented and short statured populations from Africa and the islands of the Indian and Pacific Ocean stem from a recent common source. Mitochondrial DNA evidence suggests that the so called “negrito” populations of South Asia descend from the same common founder lineages as the rest of Eurasians and cannot thus be explained by a separate migration wave from Africa.


SELECTED PUBLICATIONS

Kivisild T, Shen P, Wall D, Do B, Sung R, Davis K, Passarino G, Underhill PA, Scharfe C, Torroni A, Scozzari R, Modiano D, Coppa A, de Knijff P, Feldman M, Cavalli-Sforza LL, Oefner PJ. (2006) The role of selection in the evolution of human mitochondrial genomes. Genetics 172(1):373-87.

Kivisild, T.; Reidla M, Metspalu E, Rosa A, Brehm A, Pennarun E, Parik J, Geberhiwot T, Usanga E, Villems R. (2004) Ethiopian mitochondrial DNA heritage: tracking gene flow across and around the gate of tears. Am J Hum Genet. 75:752-770.

Kivisild, T., Rootsi, S., Metspalu, M., Mastana, S., Kaldma, K., Parik, J., Metspalu, E., Adojaan, M., Tolk, H.-V., Stepanov, V., G?lge, M., Usanga, E., Papiha, S.S., Cinnioglu, C., King, R., Cavalli-Sforza, L., Underhill, P. A., Villems, R. (2003). The genetic heritage of the earliest settlers persists both in Indian tribal and caste populations. Am J Hum Genet. 72:313-332.

Kivisild, T, Tolk, HV, Parik, J, Wang, Y, Papiha, SS, Bandelt, HJ, Villems, R. (2002). The emerging limbs and twigs of the East Asian mtDNA tree. Mol Biol Evol. 19: 1737-1751.

Kivisild, T., Bamshad, M., Kaldma, K., Metspalu, M., Metspalu, E., Reidla, M., Laos, S., Parik, J., Watkins, W.S., Dixon, M. E., Papiha, S.S., Mastana, S.S., Mir, M.R., Ferak, V., Villems, R. (1999). Deep common ancestry of Indian and western Eurasian mitochondrial DNA lineages. Current Biology 9: 1331-1334.