Speciation Genomics
Speciation is a multi-level process that unfolds over space and time. Hybrid zones offer a rich comparative framework to study and understand how the speciation process plays out over these different temporal and spatial scales. The field cricket hybrid zone, which runs along the Appalachian Mountains from Connecticut to Texas, has been extensively studied for over forty years. My research utilizes the field cricket hybrid zone and the past research done on it to understand how selection acts on the genotype and phenotype over time to understand how repeatable evolution is in a natural system.
How does plasticity of seasonal phenologies affect temporal isolation and hybridization?
Under Construction….. recorders
How do barrier phenotypes and their underlying genomic architecture persist or change over temporal scales?
Many studies have focused on the repeatability of evolution at the level of single traits/genes or in easily manipulated lab organisms. While it is much harder to understand the repeatability of selection on whole genomes in natural populations, hybrid zones are a unique opportunity to understand how divergent genomes recombine in hybrids. My current NSF Postdoctoral Fellowship research tests the hypothesis that selection on recombinant genomes is repeatable over variable temporal scales across the field cricket hybrid zone. I am (1) using patterns of introgression in the hybrid zone to test the strength and repeatability of selection across the genome, (2) associating phenotype and genotype to test whether hybridization alters the strength of reproductive barriers, and (3) comparing key genomic regions and phenotypes across areas of the hybrid zone that differ in ages of contact.
Are species boundaries an emergent property of multiple, variable barriers?
A major goal of speciation research is to understand common patterns and processes – are there themes to the origin and maintenance of biodiversity? Yet understanding commonalities in species boundaries is difficult. The goal my research with Dr. Erica Larson, through her NSF Rules of Life grant, is to understand the genomic context for variation in species boundaries using the North American field cricket hybrid zone as a model. This data will be combined with ecological and behavioral data collected by collaborators Dr. Robin Tinghitella and Dr. Luana Maroja. Building upon nearly forty years of work on the field cricket hybrid zone, our central hypothesis is that species boundaries are an emergent property of multiple, variable barriers. To test this hypothesis, we are (1) using a phenotype-driven approach that integrates ecology and behavior to measure the cumulative strength of individual barriers, (2) linking variable barriers with spatial patterns of variation in recombination, hybridization, and selection among populations, and (3) determining if the traits and genes that underly barriers between our focal species are relevant for other closely-related species.
Other Projects
How do components of sensory drive respond when other components are altered?
To investigate this, we leveraged the signal change in freshwater sticklebacks in southern Washington from red to black nuptial coloration. We consider how the alteration of environment and the evolution of visual system, signal, and behavior contribute to the maintenance of the red and black color morphs. This is an ongoing collaboration between the Larson and Tinghitella labs and Jenny Gumm at US Fish and Wildlife.
How can we quantify coupling in hybrid zones?
We know relatively little about coupling in most hybrid zones. To investigate this, we use both simulations and calculations from empirical hybrid zone datasets. This allows us to ask whether the hybrid zones we consider exhibit strong or weak coupling, as predicted by tipping point models, or form more of a connected continuum with a notable zone of intermediate systems. This is an ongoing collaboration between the Larson, Gompert, Taylor, and Dopman labs.
