Post-Doctoral Researcher
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Contact information:
Email:
Lab Phone: (520) 626-0404
Office Phone: (520) 626-1626
Fax: (520) 626-8050
Mailing Address:
Room 246B,
Biological Sciences West,
1041 East Lowell Street,
University of Arizona,
Tucson, AZ 85721, USA
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Research Interests
My research interests lie primarily in reconstructing human demographic history using inherited genetic markers. Any two people can be distinguished by minor differences in the DNA they receive from their parents. By observing these genetic variants in people living today, we can infer biological relationships and patterns of mobility far back in prehistory.
The individual demographic histories of women and men can be teased apart by analysing two special genetic systems: mitochondrial DNA, which is passed from a mother to her offspring; and the Y-chromosome, which is passed from a father to his sons. However, these genetic systems represent only two, somewhat biased, snapshots of human history.
Multiple, unlinked loci on the X-chromosome and autosomes bear considerably greater information about our complex past. I use genomic resequencing data, genetic simulation methods and coalescent modelling to reconstruct population history, with particular emphasis on human populations in the Indo-Pacific region.
Current Research
Signals of Population Expansion from the Agricultural Revolution
One current interest lies in the mid-Holocene expansion of Neolithic peoples through Island Southeast Asia and Melanesia. What was the biological contribution of Neolithic peoples to modern populations? How was Neolithic contact with pre-existing Mesolithic peoples in the region recorded genetically? The resulting biological information can only be interpreted meaningfully by comparison with archaeological, ethnographic and linguistic evidence. Future research directions include the detailed analysis of genetic diversity in small-scale geographical regions (focusing on the large-scale effects of small population variability), and the adoption of higher resolution genetic typing methodologies for reconstructing biological history in the Indo-Pacific region.
Language/Gene Associations in Solomon Islands
The Solomon Islands lie in the centre of Island Melanesia, bordered to the north by the Bismarck Archipelago, and to the south by Vanuatu. The nation's half million inhabitants speak around seventy languages from two unrelated language groups: Austronesian, a language family widespread in the Pacific, and closely related to languages spoken in Island Southeast Asia; and "East Papuan", generally defined as non-Austronesian, and related to the extremely diverse Papuan languages of New Guinea. Using paired samples from two regions with populations speaking Austronesian and Papuan languages, we are searching for traces of an association between these language families and biological variation. Such an association would be driven by divergent population histories, but confused by shared recent interactions and the effects of lineages becoming fixed or swept to extinction by genetic drift or favoured exogamy.
Human Population Genomics
Human population genetic research has traditionally focused on mitochondrial DNA and Y-chromosome variation, but the study of autosomal diversity is coming of age with improved and cheaper sequencing and genotyping technologies. Our research group is comparing patterns of autosomal variation in order to distinguish natural selection from the genomic signatures of demographic processes. We are engaged in a long-term collaborative project with Dr. Jeff Wall at the University of Southern California to gather new data and design novel analytical methods to answer long-standing questions in human evolution. One focus of this research is the evolutionary relationships of "archaic" human groups (such as the Neanderthals in Europe and Homo erectus in Asia) to modern humans. Did archaic forms make any contribution to the contemporary human gene pool, or were Neanderthals and H. erectus completely replaced (without interbreeding) by modern humans as they expanded out of Africa within the last 100,000 years? Did our ancestors make the transition to modern form in a small, isolated part of Africa, or over a broader geographic range with genetic contributions from divergent populations? Our study design of 90 loci encompassing ~1.5 Mb on the autosomes and the X chromosome in 90 humans is carefully designed to address these and related questions.
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