PROJECT SUMMARY
Genes play two different roles in biology, giving shape to phenotypes through developmental processes
within individuals, and transmitting traits across generations through Mendelian inheritance. Evolutionary
developmental geneticists work at the intersection of these roles, asking how the mechanisms that operate
within individuals influence the origin, maintenance, and fate of phenotypic variation in populations.
Pleiotropy, dominance, epistasis, polygeny, and linkage are some of the phenomena that unite developmental
and population genetics. One further class of phenomenon – early embryonic development – also bridges this
divide, involving molecular and cellular contributions from the embryo's own zygotic genome but also from
the substance of the egg, a product of its mother's genome. This dual regulation by two genomes creates
distinctive transmission genetics properties for early development, properties that alter predictions about
patterns of variation and divergence.
To better understand how maternal and zygotic genetic effects and their interactions shape variation and
evolution of development, this project sets as its goal the characterization of genetic architectures of
embryogenesis in multiple experimental model systems, each with unique complementary features.
One line of research focuses on Caenorhabditis nematodes, a longstanding experimental model for
developmental genetics. Building on the lab's extensive resources for quantitative genetic analysis in these
animals, the project will use controlled experimental crosses to reveal genetic variants that act either in the
mother's genome or in that of her offspring to influence developmental gene expression. The project will use
two experimental panels of C. elegans, one that maximizes detection power and one that maximizes mapping
resolution. To address questions about the role of mating system in maternal-zygotic coevolution, the project
will also use an experimental panel of C. becei, a closely related species that exhibits obligate outcrossing in
contrast to the self-fertilization that characterizes C. elegans.
A second line of research focuses on variation in embryonic development an annelid model system, Streblospio
benedicti. This species is unique in exhibiting both direct and indirect development as heritable variation, with
the alternative modes representing adaptive strategies to different environmental conditions. This system
provides a directional selection counterpart to the stabilizing selection that Caenorhabditis embryogenesis
experiences. Measurements of embryonic gene expression in a large S. benedicti pedigree will facilitate genetic
dissection of both maternal and zygotic contributions to development and tests of the role of maternal-zygotic
genetic interactions in driving or preventing adaptive evolution.