Population and evolutionary genetics in wild plants.

Written by:

Maya Wilson Brown

The wild polyploid lineages that we see today are just a small subset of those that have formed, as most quickly go extinct. So what makes a polyploid successfully establish?

Maya Wilson Brown smelling on a bench with plants behind her at Garfield Park Conservatory in Chicago, IL

I study population and evolutionary genetics in wild plants. I am interested in why some plants exist where they do, how they got there, and how long they are likely to stay in that area. Specifically, I study how polyploidy (whole genome duplication) impacts plant population establishment and persistence. Polyploid plants are ubiquitous in nature– it's widely accepted that all flowering plants have at least one whole genome duplication event in their evolutionary history. When polyploids form, however, they face a lot of intrinsic (genetic and genomic) and extrinsic (population and ecological) challenges. The wild polyploid lineages that we see today are just a small subset of those that have formed, as most quickly go extinct. So what makes a polyploid successfully establish?

Diverse fields engage in polyploid evolutionary research from theory to genetics and ecology. For a long time, we lacked the genomic and computational tools to go evaluate a lot of the theory that was developed for polyploids. Given the tools and data we now have, I am excited to participate in the next era of polyploid research, which I believe is the empirical validation of adaptive traits in polyploids. My goal, like most evolutionary geneticists, is to be able to identify genetic and genomic variants, link those variants to different phenotypes, and evaluate how differences between phenotypes affect the fitness of individuals– with the added complexity of working within organisms that have multiple genomes.

My research focuses on allopolyploids, which represent whole genome duplication with hybridization between species (as opposed to autopolyploids, where whole genome duplication occurs within a species). I work with Capsella bursa-pastoris (common name: shepherd’s purse) which is a weed in the family Brassicaceae that is found all over the world, although it is not common in tropical climates. It formed in the Mediterranean region as a hybrid between Capsella grandiflora and Capsella orientalis, both of which are diploid and have very limited ranges.

Capsellabursa-pastoris plans growing in small pots in a growth chamber at Michigan State University

There are several aspects of C. bursa-pastoris’ biology that are assumed to contribute to its large range– fixed heterozygosity, gene flow with other Capsella species, increased plasticity, high self-fertilization rate, and improved competitive ability, just to name a few– but not many have been explicitly tested or compared to its progenitors. Yes, there are many things that could help polyploids establish, but do they? If many advantages are present, what is their relative importance? Is that dependent on the environmental, demographic, and evolutionary context?

One of the best parts of working in polyploid plant evolution is the chance to utilize interdisciplinary approaches. My research background is in plant evolutionary genetics and speciation, and I am excited to dig deeper into population genetic theory, gene expression analyses, and ecology! Furthermore, this work has broad applications in the management of invasive species, crop development (my favorite polyploid crop is coffee), and predicting the fate of populations with climate change.

Maya Wilson Brown collecting seeds at a local park on the rare occasion her work takes her outside. She is typically seated in front of a computer while working.