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How early does the selfing syndrome arise? Associations between selfing ability and flower size within populations of the mixed mater Collinsia verna

Citation

McElderry, Robert M; Spigler, Rachel B; Vogler, Donna W; Kalisz, Susan (2022), How early does the selfing syndrome arise? Associations between selfing ability and flower size within populations of the mixed mater Collinsia verna, Dryad, Dataset, https://doi.org/10.5061/dryad.s1rn8pk8v

Abstract

Widespread associations between selfing rate and floral size within and among taxa suggest that these traits may evolve in concert. Does this association develop immediately, because of shared genetic/developmental control, or stepwise with selection shaping the evolution of one trait following the other? If the former, then association ought to appear within and across populations. We explore this fundamental question in three populations of the mixed-mater Collinsia verna where autonomous selfing (AS) ability has been shown to be under selection by the pollination environment. We grew clonal replicates of C. verna in a controlled environment to characterize broad-sense genetic correlations among traits within populations and to assess whether divergence in mating system and floral traits among these populations is consistent with their previously observed selection pressures. As predicted by their respective pollination environments, we demonstrate significant genetic divergence among populations in AS ability. However, patterns of divergence in floral traits (petal, stamen, and style size, stigmatic receptivity, and stigma-anther distance) were not as expected. Within populations, genetic variation in AS appeared largely independent from floral traits, except for a single weak negative association in one population between flower size and AS rate. Together, these results suggest that associations between selfing rate and floral traits across Collinsia species are not reflected at microevolutionary scales. If C. verna were to continue evolving toward the selfing syndrome, floral trait evolution would likely follow stepwise from mating system evolution.

Methods

Experimental Design

Genotypes from 3 populations: Enlow Fork (EF), Braddock Trail (BT), and Ten Mile Creek (TMC),all in Western Pennsylvania, were cloned in 1999, and clones were designated to either the morphology study or the autogamy study. Genotypes 100-199 are from EF, 200-299 are from BT, and 300-399 are from TMC.

Multiple floral traits were measured together on single flowers, and several flowers were measured for each clone. Stigmatic receptivity was measured on several flowers per clone, but not the same flowers that were measured for floral traits. Autonomous selfing ability was measured on different clones of the same parent plant (genotype) from which clones originated that were measured for floral traits and receptivity. To account for this sampling scheme, Floral traits and stigmatic receptivity were aggregated to clonal means before merging them together. To merge with selfing ability, clonal mean trait values were aggregated to genotypic means to match the level of selfing measurement.

Usage Notes

There are three comma separated files comprising this dataset, which does contain some missing values. Metadata are described in the README file and in the annotated R script "McElderry_etal_GenVarSelfing.html".

Funding

National Science Foundation, Award: DEB 9726980

National Science Foundation, Award: DEB 0324764