Hopi Hoekstra
Assistant Professor of Biology, UCSD

e-mail: hoekstra@ucsd.edu
Lab Homepage

     Biological variation is the cornerstone of evolution. My research focuses on understanding how variation is generated and maintained in natural populations. I am particularly interested in the role of natural selection in shaping adaptive genetic and phenotypic variation. I use an integrative approach combining molecular genetic techniques, theoretical modeling, experimental tests, breeding studies and fieldwork. With the imminent completion of the mouse genome, natural populations of rodents are ideal systems in which both genetic and ecological information is available to address these questions.

    The long-term goals of my research are two-fold: (1) to understand the genetic basis of adaptive phenotypes, and (2) to understand how natural selection affects DNA nucleotide variation and gene expression. To this end, we are currently studying the following systems:

Molecular population genetics of adaptive color:
    Current work focuses on understanding the genetic basis of color variation in Chaetodipus intermedius, the rock pocket mouse. In the desert southwest, several isolated lava flows, which are primarily dark, basaltic rock provide excellent habitat for the rock pocket mouse. These lava-dwelling mice have extremely dark coat-color, an adaptation that makes them less conspicuous to aerial predators. It is likely that this dark pelage color has arisen multiple times independently on different lava flows. I am interested in both the molecular basis and functional consequences of mutations that underlie the adaptive dark coloration, and the effect of selection on DNA nucleotide variation in these pigmentation genes.

Genetic basis of complex phenotypes:
    In a new project, I am working to understand the genetic basis of more complex color variation in Peromyscus polionotus, the oldfield mouse. These mice occur on sandy islands of the coast of Alabama and Florida. Like the beach sand, these mice are extremely light-colored, but show variation in pigmentation patterns between isolated islands. It is likely that several genes contribute to this adaptive coloration and these genes differ between islands. Using mapping techniques and microarrays to uncover the genes involved in this adaptive phenotype will allow us to address the following questions: How many genes contribute to this adaptive trait? Can we identify the specific nucleotide changes that are responsible for phenotypic change? Are these changes in regulatory or structural regions, and do they affect gene expression or protein function?

Evolution of sex chromosomes:
    In a third system, I study species of South American field mice (genus Akodon). In several but not all species of Akodon there is a sex chromosome polymorphism: some females are XX and others are XY. In these mice, the Y chromosome doesn't always function properly in sex-determination, resulting in XY females. I am studying the evolution of this polymorphism in natural populations. Specifically, I am interested in how the polymorphism arose and is maintained in natural populations, and how it affects female fitness.


      Hoekstra, H.E. and M.W. Nachman. (2003). Different genes underlie adaptive
melanism in different populations of pocket mice. Molecular Ecology 12:1185-94.

      Nachman, M.W., Hoekstra, H.E. and S. L. D'Agostino. (2003). The genetic basis of adaptive melanism in pocket mice. Proceedings of the National Academy of Sciences. 100(9): 5268-73.

     Hoekstra, H. E. (2003). Unequal transmission of mitochondrial haplotypes in
natural populations of field mice with XY females (genus Akodon). The American
Naturalist 161(1): 29-39.

     Hoekstra, H.E., Hoekstra, J.M. Berrigan, D., Vigneri, S.N., Hill, C.E., Hoang, A, Beerli, P. and J.G. Kingsolver. (2001). Strength and temp of directional selection in the wild. Proceedings of the National Academy of Sciences. 98(16): 9157-9160.

     Hoekstra, H.E. and J.M. Hoekstra. (2001). An unusual sex-determination system in South American field mice (genus Akodon): the role of mutation, selection and meiotic drive in maintaining XY females. Evolution 55(1): 190-197.

     Hoekstra, H.E. and S.V. Edwards. (2000). Multiple origins of XY mice (genus Akodon): phylogenetic and chromosomal evidence. Proc. Roy. Soc. London B 267(1445):1825-1831.

     Hopi Hoekstra received her BA in Integrative Biology from UC Berkeley in 1995 and completed her Ph.D. at the University of Washington in 2000 as a Howard Hughes Fellow. She was a NIH Postdoctoral Fellow at the University of Arizona. Hopi was the recipient of the Ernst Mayr Award from the Society of Systematic Biologists and recently, she was awarded The Young Investigator's Prize from the American Society of Naturalists.