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[Molecular Evolutionary Genomics; Population Genetics; Speciation; Evolutionary Cell Biology; Adaptation; Caenorhabditis]

In the Cutter lab, we study the genetic basis of evolutionary change. We are particularly interested heritable changes through time with causes that are at the interface of natural selection and non-adaptive evolutionary forces. Our research currently centers on 3 broad themes: Population genomics and genome evolution, the genetics of speciation, and evolutionary cell biology.

We exploit C. elegans -- a classic model organism in genetics, development and neurobiology -- and related species as a model to dissect these diverse problems in evolutionary genetics. Caenorhabditis is an exceptional group to study the evolutionary process at molecular and phenotypic levels for many reasons: The genomes of Caenorhabditis species are modest in size and complexity (6 chromosomes, 100-150Mbp long, no genome duplications), species differ in effective population size (Ne: 104 - 106) and mode of reproduction (selfing hermaphrodites vs. dioecious separate sexes), behaviors and fitness may be quantified simply due to experimental tractability (1mm long, 3 day generation time, rearing on bacteria-spotted petri dishes), and abundant genetic and molecular tools from the C. elegans research community (RNAi, mutant/knockout alleles, transgenic strains).

Population genomics and genome evolution
Building on locus-based data analyses of population genetic variation and advances in high-throughput DNA sequencing, we are quantifying patterns of sequence differences of entire genomes for individuals within and between populations and species in order to understand the evolutionary processes underlying genome evolution. We are particularly interested in the interface between evolutionary forces -- to elucidate the interplay between natural selection, recombination, mutation, genetic drift, and population demography. We aim to identify how adaptation and purifying selection alter the landscape of sequence variation and divergence across the genome, understand the extent to which crossover recombination and gene conversion affect natural selection and evidence of its action, quantify the extent to which different mutational processes impact inferences about selection and demographic history, and determine the role of very weak natural selection on genomic features. A major recent component of this work is to dissect the present-day molecular evolutionary pressures affecting small RNA genes, like miRNAs and piRNAs.

Genetics of reproductive isolation
We are capitalizing on the recent identification of new Caenorhabditis species that permit the formation of inter-species hybrids to study the genetic basis of reproductive isolation -- "speciation genetics." This includes characterizing the causes of Haldane's Rule (disproportionate inviability/sterility of heterogametic hybrid progeny) and Darwin's Corollary to Haldane's Rule (parent-of-origin asymmetry in hybrid viability/fertility), as well as identifying segregating intra-specific variation for inter-specific hybrid viability/fertility.

Genetic basis of natural phenotypic variation
We have documented striking latitudinal phylogeographic patterns for C. briggsae populations from around the globe, with corresponding correlations with temperature-dependent traits. We are interrogating a panel of recombinant inbred lines (RILs) of this species to characterize the causal quantitative trait loci (QTL) and nucleotides (QTN) responsible for this natural phenotypic variation that might derive from local adaptation.

Causes and consequences of breeding system evolution
Hermaphrodites capable of self-fertilization have evolved from female ancestors several times within the Caenorhabditis genus. We are using experimental evolution and behavioral assays to understand how this major lifestyle shift affects the species involved and what factors favored the repeated origin of selfing hermaphroditism. We hope to elucidate whether traits associated with a "selfing syndrome" in this group evolved via adaptation to hermaphroditism or due to relaxed selection on ancestral female and male traits.

Portions of these projects involve collaboration with the labs of Scott Baird (Wright State U.), Christian Braendle (CNRS Nice), Julie Claycomb (U. Toronto), Marie-Anne Felix (Ecole Normale Superieure), Bret Payseur (U. Wisconsin), Patrick Phillips (U. Oregon), William Ryu (U. Toronto) and Lincoln Stein (OICR).

For more details, see the Projects page and our Publications, or find out more information about current research opportunities in the Cutter lab.

 

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text & photos 2006-2016 by asher d. cutter. design 2006 by yee-fan sun