Divergent allocation strategies between annuals and perennials in the field

Within a species, geographic populations often diverge as they adapt to their local environments. Such divergence can be an early step in speciation, especially when it results in reproductive isolation and a reduction of gene flow. In the wildflower Mimulus guttatus, local adaptation is observed with variation in life history strategies. Annual plants flower early and invest very little in vegetative growth, whereas perennials spend more time growing vegetatively before reproducing. My study investigates the genetic basis of these alternative strategies in the field using an F4 cross between parent populations representative of the two ecotypes. I grew 24 replicates of each inbred parent and 537 F4 offspring. Phenotypic observations taken in the field assessed allocation to vegetative versus reproductive growth, as well as overall fitness. DNA collected in the field, extracted in the lab, and sequenced at the University of Rochester will be combined with phenotypic data for Quantitative Trait Loci (QTL) mapping. This will identify regions of the genome that explain phenotypic variation, and comparisons of the QTL for multiple traits will indicate the role of linkage or pleiotropy in the evolution of M. guttatus. Current results come from correlations in the phenotypic data. They show that while some traits that were correlated in parent populations are broken up by the rounds of recombination in the F4 population (e.g. stolon number and flower number); other traits remain linked (e.g. flowering date and senescence). These results suggest that evolution may act on combinations of traits as populations become adapted to their environments