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The evolution of gene function
Since Darwin, the central task of evolutionary biology has been to
provide a historical explanation for biodiversity -- the incredible
number of species in nature, each with features so well adapted it to
its environment. With the rise of molecular biology, a new level of
biodiversity has emerged which demands an explanation -- the great
variety of genes in our genomes, each with highly specialized and
well-optimized functions. We would like to understand the evolutionary
dynamics that have determined how genes -- or more accurately, the
proteins they code for -- got their functions. We employ a synthesis of
evolutionary and phylogenetic techniques with functional molecular
biology. Our current model system is a gene family of great biological
and biomedical importance.
Molecular evolution of hormones and their receptors
How did hormones and their diverse functions in humans and other
animals evolve? We study the evolution of vertebrate steroid hormones
-- such as estrogen, testosterone, and the stress hormone cortisol --
and the receptor proteins that mediate these hormones' effects on the
body's cells. Our goal is to reveal the specific molecular events by
which hormones and receptors diversified and evolved their specific
partnerships. By combining techniques from statistical phylogenetics,
molecular endocrinology, ancestral gene resurrection, and experimental
evolution, we are characterizing receptor biodiversity across the
animal kingdom, reconstructing the evolution of the family at the
genetic level, and testing hypotheses about the functions of ancient
genes. Our goal is to illustrate how a complex, tightly integrated
molecular system evolved by Darwinian processes hundreds of millions of
years ago.
Phylogenetic techniques
We are also evaluating and developing new phylogenetic methods for
analyzing gene family evolution. We are particularly interested in
understanding how heterogeneity in the evolutionary process affects the
accuracy of current techniques, and in developing new methods that
perform better when sequences evolve differently among sites and
lineages.
Environmental health and policy
Many pesticides and industrial chemicals can cause severe effects on
reproduction, development, behavior, and immunity, because they mimic
or block the actions of our body's steroid hormones. I have long been
interested in how scientific knowledge can be used to support policies
that protect both natural systems and democratic principles. We are
working to help insure that environmental policies take better account
of the complexity and diversity of animal endocrine systems and
contribute to long-term reductions in the production and use of
persistent toxic chemicals. This work builds on the argument made in my
book Pandora's Poison.
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