Two of the deepest questions in biology are (1) why are there different sexes and (2) what are the functional and evolutionary consequences of this sexual differentiation. As an evolutionary genetics lab, we strive to identify the mechanisms underlying the transition of monomorphic to sexually dimorphic traits. Our research leverages the power of the Caenorhabditis nematode model systems to relate the action of sex-specific selection on phenotypes to the evolution of their genetic architecture. We use an integrative, strong hypothesis-testing approach to discover how sexual differentiation arises, persists, and impacts genomes.
We currently have three major research themes in the lab:
Theme I: What is the role of sexually antagonistic selection in shaping genome evolution?
A core question in modern population genetics is: How is genetic variation maintained? Sexually antagonistic selection can maintain genetic variation when the conflict between the sexes arises from a single allele that is beneficial when expressed in one sex and deleterious when expressed in the other. Theory indicates that multiple genetic mechanisms can maintain, moderate, or resolve conflict in genomes. Yet, little empirical data exist that quantify the relative likelihood of these alternative mechanisms. Additionally, the evolutionary trajectory of alleles at a locus is sensitive to the patterns of haplotype structure, pleiotropy, and epistasis in the surrounding genome. These features typically vary along autosomes and differ between autosomes and sex chromosomes as well as differing between the sexes. Currently, we do not have good metrics to confidently infer ongoing sexually antagonistic selection in genomes or definitively attribute genomic features to conflict resolution. Our research integrates genetic engineering, experimental evolution, and genomics to understand how sex-biased selection acts as an organizing principle in the genome and drives genome evolution.
Theme II: What are the molecular networks underlying reproductive traits?
Interlocus sexual conflict arises independently of the shared genome (unlike intralocus sexual conflict) as a result of interactions between the sexes, such as different optimal mating rates. As selection acts to optimize fitness in one sex, the fitness of the interacting sex is decreased, which can lead to antagonistic evolutionary arms race. If maintained, sexually antagonistic co-evolution can rapidly lead to population divergence and potentially speciation. Additionally, interlocus sexual conflict can lead to intralocus sexual conflict, which creates the potential for further genome evolution. Our research capitalizes on advances in genetic manipulation and sequencing to map the genetic basis of sexually antagonistic co-evolution during mating and examine how it contributes to genome evolution. A comprehensive understanding of a key and taxonomically widespread mating interaction will provide foundational insights on where sex differences arise across the genotype-phenotype landscape and how they are shaped by sex-specific and sexually antagonistic selection.
Theme III: What is the ecological context of sexual conflict?
The field has long recognized that the ecological context surrounding mating interactions impacts the degree and type of sexual conflict. Much of this foundational work has focused on phenotypes rather than the genomic consequences of sexually antagonistic selection. Nematodes provide an excellent opportunity to bridge the genetic and genomic understanding of a model organism with the ecological relevance of selection. Currently, we know little about the ecological context of mating interactions in natural populations of Caenorhabditis nematodes. Our research aims to address when sexual conflict impacts evolution in nature to determine the conditions under which this evolutionary force is relevant to genome evolution. We first are establishing sampling sites at Mountain Lake Biological Station.
conflict genomics 