Faculty Research: Stephen Proulx

Much of my current work is focused on understanding the evolutionary forces that structure genomes, taking into account selection on phenotypes, population dynamics, and population genetics. Do genomes evolve to be robust? How do multi-gene families form? How does gene regulation evolve? Should regulation be simple or involve complex feedbacks? What evolutionary forces act to shape the machinery of DNA replication, transcription, and translation?

Gene Duplication

Selection for alternative genetic functions can be generated by selection for multiple functions within an organism and by variable environmental conditions. We have previously shown that selection for multiple functions can select for genetic divergence even before duplication, a process we call allelic divergence. This process causes novel genetic function to evolve via small mutations and promotes the spread of gene duplicates by natural selection. We are currently exploring specific sources of within-organism variability including gene regulation, dimerization, and alternative splicing.

Canalization, Robustness, and Plasticity

A continuing theme in my lab is the relationship between genetic canalization and phenotypic plasticity. In the real world, animals from a single species may inhabit very different environments even over small distances. We are exploring how evolutionary processes respond to the costs of gene flow. Under some scenarios we predict that local populations should evolve genotypes that are genetically canalized to immigrant alleles and genotypes produce consistent phenotypes. Alternatively, phenotypic plasticity could resolve the cost of gene flow. We are investigating the relationship between the genetic basis of plasticity and the likelihood that a species will evolve to be canalized or plastic.

Evolution of Genetic Regulatory Mechanisms

Another way for an organism to adapt to changing environments is to change the genes that it presents to the environment through transcription regulation. While there is clearly an engineering advantage to matching gene expression to environmental demands, the evolution of gene regulation requires intermediate steps that may not be adaptive themselves. To better understand this process we have begun to model the evolutionary changes that are needed to evolve transcription regulation. We are finding that the most common path to gene regulation is through an intermediate stage where fixed expression levels balance costs and benefits of operating in multiple environments. This creates a scenario where targeted changes in transcription are favored and complete gene regulation can evolve.

Stephen Proulx | Research | Publications | Curriculum Vitae

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