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430 Clinical Research Building | 415 Curie Blvd. | University of Pennsylvania | Philadelphia PA 19104-6145
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Joseph Lachance, Ph.D.Postdoctoral researcher Department of Genetics |
Research
Human evolutionary genomics
In December 2010 I joined the Tishkoff lab to study the evolutionary genomics of diverse African populations. High coverage whole-genome sequencing allows us to analyze the genetics of populations without the confounding effects of SNP ascertainment bias. I’m excited about disentangling ancient population structure from the molecular signature of natural selection, and it is particularly interesting that some regions of the genome are more likely to introgress between different populations. How do molecular processes and evolutionary processes combine to shape variation found in human genomes? How do the genomes of African hunter-gatherers differ from the genomes of individuals with other subsistence patterns? Also, why do disease risks vary from population to population? My past work has addressed how long it takes for all humanity to share a common ancestor and whether alleles implicated in genome-wide association studies differ from the rest of the genome.
Theoretical population genetics
I am broadly interested in the population-level processes that affect genetic variation, and there’s something truly neat about being able to explore the big ideas of evolutionary biology with mathematical rigor. My theoretical work has addressed the following questions:
- How does natural selection constrain the observable set of genotype frequencies?
- Does epistasis change the rate of adaptation?
- How do synthetic incompatibilities and incomplete penetrance modify allele frequency trajectories?
- What is the probability that hybrid incompatibilities are shared between multiple species?
Drosophila genetics
As part of my Ph.D. work with John True, I studied the effects of genetic background in Drosophila melanogaster. We found substantial levels of synthetic lethality and sterility between naturally segregating X chromosomes and autosomes. We also examined whether Haldane’s rule (whereby the heterogametic sex is more likely to have lower fitness) applies to divergent populations within the same species. Another interesting finding involved natural variation at the vesiculated locus. This allele was incompletely penetrant, and we found evidence that penetrance was modulated by genetic background, temperature, genotype-by-environment interactions, and maternal effects.
Education
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Ph.D. |
Genetics, Stony Brook University, 2010 Graduate-level studies in genetics, Duke University, 1996-1997 |
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A.B. |
Biology, University of Chicago (advisor: Chung-I Wu), 1996 |
Academic Positions
Current position: NIH Postdoctoral Fellow in Sarah Tishkoff’s lab at the University of Pennsylvania
Grants Awarded
2011-2014
NIH F31 Kirschstein National Research Service Award: Population genomics of geographically and ethnically diverse Africans (NHGRI, F32HG006648)
2010
Selected to give a university-wide lecture as part of the Provost’s Graduate Student Lecture Series at Stony Brook University
2009
Detecting selection-induced departures from Hardy-Weinberg proportions” was among the yearly top 10 most accessed articles in GSE
Summer Institute in Statistical Genetics fellowship recipient at the University of Washington (comparative genomics and molecular evolution, coalescent theory)
Cedar Brook Award for best student talk at the Ecology and Evolution departmental retreat at Stony Brook University
“Subject to Change” featured as an exceptional Nature Futures story by Concatenation (www.concatenation.org)
2008
Stony Brook graduate student organization Research Access Program funding
2007
King-Miller travel award to attend the Evolution 2007 conference in Christchurch, NZ
2005 – 2007
NIH Predoctoral training grant fellowship, Stony Brook University
1996 – 1997
NIH Predoctoral training grant fellowship, Duke University
1995
Howard Hughes summer undergraduate fellowship
1992 – 1996
National Merit Scholar, University of Chicago
Teaching Experience
2012
Instructor: University of Pennsylvania
Co-taught a seminar course for undergraduates on human evolutionary genomics
2011
Guest Instructor: University of Pennsylvania (Perelman School of Medicine)
Led population genetics discussions for medical students
2006 – 2012
Mentor: Stony Brook University and the University of Pennsylvania
Helped guide the research of five high school students, four undergraduates, and three Ph.D. students (work presented at URECA, LISEF, Intel, and Siemens science fair competitions)
2007-2009
Guest Instructor: Stony Brook University
Assisted in field laboratory components of a molecular diversity class for undergraduate and graduate students.
2009
Guest Instructor: Stony Brook University (CESAME)
Introduced high school students to a range of genetics research projects
2008
Lecturer: Stony Brook University
Taught the population genetics and evolutionary developmental biology block of a Ph.D.-level course in genetics
1996
Teaching Assistant: University of Chicago
Assisted in the teaching of a genetics course for non-majors
Publications
Research Publications
Lachance J, Johnson N, and True JR (2011) The population genetics of X-autosome synthetic lethals and steriles. Genetics 189:1011-1027.
Lachance J (2010) Genome-wide association studies reveal that disease associated alleles are enriched for derived low frequency alleles relative to HapMap and neutral expectations. BMC Medical Genomics 3:57.
Lachance J and True JR (2010) X-autosome incompatibilities in Drosophila melanogaster: tests of Haldane’s rule and geographic patterns within species. Evolution 64:3035-3046.
Lachance J (2009) Inbreeding, pedigree size, and the most recent common ancestor of humanity. Journal of Theoretical Biology 261: 238-247.
Lachance J (2009) Detecting selection-induced departures from Hardy-Weinberg proportions. Genetics Selection Evolution 41:15.
Lachance J (2008) A fundamental relationship between genotype frequencies and fitnesses. Genetics 180:1087-93.
Yukilevich R, Lachance J, F. Aoki F, and True JR (2008) Long-term adaptation of epistatic genetic networks. Evolution 62:2215-2235.
Other Publications
Lachance J (2011) Book Review: How Many Friends Does One Person Need? By Robin Dunbar. Quarterly Review of Biology 86:104.
Lachance J and Bourdeau P (2010) Evolution by Doug Futuyma: online supplements, 2nd ed. Sinauer Associates, Sunderland MA.
Lachance J (2009) Book Review: Evolving Pathways edited by Alessandro Minelli and Giuseppe Fusco. Quarterly Review of Biology 84:102-103.
Lachance J (2008) Subject to Change. Nature 454:916.
Lachance J (2008) Forgotten Ancestors. University of Chicago Magazine 100:6.
Lachance J (2008) Book Review: Modelling for Field Biologists and Other Interesting People by Hanna Kokko. Quarterly Review of Biology 83:296.
Lachance J (2007) Book Review: Compositional Evolution by Richard A. Watson. Quarterly Review of Biology 82:148-149.
2007 – present: Reviewed publications for: Evolution, Faculty of 1000 (associate member), Genes and Genetic Systems, Genetica, Genetics, Journal of Theoretical Biology, Molecular Biology and Evolution, Quarterly Review of Biology
2009 – 2010: Served as student representative in the executive committee of Stony Brook University’s graduate program in genetics
2007 – 2009: Led discussions for Darwin Day at Stony Brook University
2005 – 2009: Philosophy of biology discussion group: organized meetings for multiple semesters
2007 – 2009: Orientation: TA roundtables (advised new TAs about teaching at Stony Brook University)
2009: Generated preliminary data and assisted in writing a successfully funded NIH grant (Metabolic and dopamine pathways in energy sensing and adaptation in Drosophila, R01GM090094)
2008: Reviewed applications for the King-Miller travel scholarship
2006: Assisted in organizing the SSE’s Evolution 2006 conference
