Ecological and evolutionary genetics in Ecology and Evolutionary Biology at UofT. Dad, dog lover, unashamed coffee addict.
John Stinchcombe
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Why are leaves the shape that they are? What controls intraspecific, genetic variation in leaf shape?
New from my lab, in collaboration with many others, led by PhD student Amanda Peake: mapping the leaf shape polymorphism in Ipomoea hederacea.
Check out the preprint, and comments welcome!
Congrats to Amanda Peake on leading this project to this point, and thanks to anyone I've ever talked to about morning glories or leaf shape.
John Stinchcombe
A combination of comparative and other analyses suggest the indel is a deletion in the entire-leaf genotypes, and it appears to be newly arisen in I. hederacea. Other morning glories with similar heart-shaped leaves are lacking the deletion, and related species appear to have the deletion intact.
Progress on the genetics, ecology, and evolution of this polymorphism has been stymied by the lack of genomic resources in this species.
With collaborators, we built a reference genome for Ipomoea hederacea, and re-sequenced 123 lines to map the leaf shape locus.
In addition, these results suggest that there could be multiple ecological agents acting on the cline, in addition to the effects of the indel in producing shape itself.
The genes on the indel itself are implicated in a host of physiological processes that could affect water relations, herbivory, and plant-microbe interactions. This could potentially explain some of ecological differences we've documented between leaf shapes.
Lobed genotypes predominate in Northern populations, apparently due to selection. Several students -- Brandon Campitelli, Anna Simonsen, Julia Boyle, Georgia Henry, Yash Singhal-- have documented subtle ecological differences between shapes, but had a hard time identifying a strong selective agent.
A GWAS indicates that the leaf shape locus is on Chromosome 2, and coverage analyses indicate that it is a ~117 kb indel. The indel perfectly co-segregates with leaf shape. The indel is relatively close to two auxin-related genes implicated in leaf shape and development.
