Miller Postdoctoral Fellow

Statistics

Integrative Biology

University of California, Berkeley (Berkeley, CA)

Graduate Student - Ph.D.

Integrative Biosciences

Center for Comparative Genomics and Bioinformatics

Pennsylvania State University (University Park, PA)

Rasmus Nielsen

Mammalian Sex Chromosome Evolution

Since the two eutherian sex chromosomes diverged from an ancestral autosomal pair, the X has remained relatively gene-rich, while the Y lost most of its genes through the accumulation of deleterious mutations in nonrecombining regions. Presently, it is unclear when the sex chromosomes acquired their unique evolutionary rates, what is distinctive about the genes remaining on the Y chromosome, and whether X-Y gene divergence paralleled that of paralogs located on autosomes. To tackle these questions, we juxtapose the evolution of X and Y homologous genes (gametologs) in human, chimpanzee and mouse with their autosomal orthologs in opossum and platypus. We discovered that genes on the X and Y acquired distinct evolutionary rates immediately following the suppression of recombination between the two sex chromosomes. The Y-linked genes evolved at higher rates, while the X-linked genes maintained the lower evolutionary rates of the ancestral autosomal genes. We further established that, surprisingly, the surviving gametologs had less radical and fewer overall amino acid changes than did autosomal paralogs. Curiously, in contrast to expectations, most Y gametologs evolved under stronger purifying selection than the quickly evolving copies of autosomal duplicate pairs. Finally, after evaluating expression and functional laboratory experiments, we concluded that, to be retained on both the X and the Y, gametologs evolved unique mRNA and protein expression patterns as well as separate functions.

2009-2010 Women in the Sciences and Engineering Institute, Internal Advisory Board member

2008-2010 Inside the Scientists Studio interview series chair

2007-2010 Voices conference planning committee member

2007-2010 Girl Scout Workshop, chair

2009 WISE Camp Afternoon Workshop committee member

2009 Commission for Women, Achieving Woman Awards review committee member

2008-2009 Biology Department, Graduate Affairs Committee representative

2008-2009 International Women's Day Award Committee, member

2008-2009 Bioinformatics and Genomics Journal Club, coordinator

2008-2009 Pennsylvania Junior Academy of Science, judge

2007-2009 Graduate Women in Science president

2007-2009 Commission for Women, Executive committee member

2007-2009 Biology Department, Graduate Recruiting Committee, member

2007-2009 Commission for Women, Marketing committee chair, co-chair

2006-2009 Integrative Biosciences, new student mentor

2006-2009 Graduate Students as Teachers

2006-2009 Women in the Sciences and Engineering Ribbon Week committee chair, member

2008 WISE Camp and WISE Day Camp, Workshop Coordinator

2008 Tyrone Science Day Workshop, organizer

2008 The Munich Graduate Program EES Summer School on the Evolution of Sex Chromosomes

2006-2008 Commission for Women, Assessment committee member

2007 WISE Week Day Camp, Program Assistant

2006-2007 Graduate Women in Science, vice-president

2004 Mathematical Biology Summer REU at University of Nebraska at Lincoln

2007-present NSF Graduate Research Fellow

2009 Sex & Recombination: In Theory and Practice Conference Travel Fellowship

2008 Women in the Sciences and Engineering Outstanding Service Award

2007 J. Ben and Helen D. Hill Memorial Award

2006 The Pennsylvania State University NSF GRFP Incentive Award

2006-2009 Institute of Molecular Evolutionary Genetics Travel Grant

2005-2006 Huck Institutes of the Life Sciences Fellowship

2005-2006 Huck Institutes of the Life Sciences Supplemental Award: For academic excellence

2005 Creighton University Outstanding Mathematician Award

2005-2006 Graham Endowed Fellowship: University-wide recognition of highly recruited students

2001-2005 Creighton University Academic Scholarship