Detection of structural variants among inland annual and coastal perennial ecotypes of the yellow monkey flower, Mimulus guttatus
Authors: Leslie Kollar; David Lowry; Chad Niederhuth
Affiliation: Michigan State University, East Lansing, MI
Keywords: Other (Adaptation)
The natural world consists of a mosaic of environments that drives adaptive divergence among natural populations. A critical gap in our knowledge of understanding how heterogenous environments drive evolutionary adaptation is establishing the role of structural variants (SV) in those adaptations. Our ability to identify SVs, especially chromosomal inversions, is limited by genome assemblies (i.e. our power to resolve repeat regions). Here, we use long-read Oxford Nanopore sequencing to identify large structural variants that differ between inland annual and coastal perennial ecotypes of the yellow monkeyflower, Mimulus guttatus. The inland populations of M. guttatus are characterized by an adaptive early flowering annual life history driven by summer drought, whereas the coastal populations of M. guttatus have a late-flowering perennial life history, as these populations are protected from drought stress by a pervasive marine fog. Additional abiotic factors such as oceanic salt spray in coastal habitats may play a key role in adaptation within this species. Research has identified QTLs linked to adaptive divergence between the ecotypes, some of which are localized to a large chromosomal inversion. Using these genomes, we identified SVs and began to resolve a decade long obstacle of identifying the breakpoints of a large chromosomal inversion thought to be involved in the adaptive divergence of M. guttatus. Additionally, we have clarified a list of genes located within the chromosomal inversion with some previously identified as responsible for adaptive phenotypes. Collectively, these genomes will lay the foundation for future research in understanding the role of structural variants, specifically chromosomal inversions, in adaptation.