Post-Doctoral Researcher
View CV | Download CV as .pdf
Contact information:
Email:
Lab Phone: (520) 626-0404
Fax: (520) 626-8050
Mailing Address:
Room 246,
Biological Sciences West,
1041 East Lowell Street,
University of Arizona,
Tucson, AZ 85721, USA
|
Current Research:
Skin pigmentation is an example of a complex trait that has likely been shaped by natural selection in response to varying levels of ultraviolet radiation (UVR). While hypotheses exploring the role of selection in shaping normal variation in human skin pigmentation abound, these hypotheses have rarely been tested using population genetic data. In particular, questions addressing the timing and strength of selection in different populations are often ignored.
I am currently sequencing regions of eleven pigmentation candidate genes in six populations that differ in skin pigmentation and that occupy environments of varying UVR intensity. Various summaries of the data based on linkage disequilibrium, FST, and the site frequency spectrum are compared to expectations under a neutral model to assess the potential role of selection in shaping variation at these loci in one or more populations. However, as non-neutral demographic processes may leave footprints in the genome that are similar to those observed following a selective sweep I am also comparing variation in these pigmentation loci to variation observed in an empirically
neutral dataset of 90 non-coding loci sequenced as part of the Hammer Lab's
Hominid Project
Some questions that I am interested in addressing are:
- Can similarities in pigmentation phenotype among populations living in low (or high) UVR environments be attributed to selection for the same genetic loci, or instead is this similarity in phenotype due to convergent evolution?
- Does the onset of selection for favored pigmentation alleles coincide with major colonizations of novel UVR environments (e.g. the arrival of anatomically modern humans to Europe)?
- Do patterns of genetic variation support the hypothesis that pigmentation variation has been constrained in high UVR regions due to purifying selection?
- Is the evolution of lighter pigmentation in low UVR regions due to a relaxation of functional constraint or instead to positive directional selection?
|
|
