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Intercontinental dispersal and whole‐genome duplication contribute to loss of self‐incompatibility in a polyploid complex

Citation

Sutherland, Brittany; Quarles, Brandie M.; Galloway, Laura F. (2021), Intercontinental dispersal and whole‐genome duplication contribute to loss of self‐incompatibility in a polyploid complex, Dryad, Dataset, https://doi.org/10.5061/dryad.cfxpnvx5n

Abstract

Premise of the Study

Angiosperm species often shift from self-incompatibility to self-compatibility following population bottlenecks. Across the range of a species, population bottlenecks may result from multiple factors, each of which may affect the geographic distribution and magnitude of mating-system shifts. We describe how intercontinental dispersal and genome duplication facilitate loss of self-incompatibility.

Methods

Self and outcross pollinations were performed on plants from 24 populations of the Campanula rotundifolia polyploid complex. Populations spanned the geographic distribution and three dominant cytotypes of the species (diploid, tetraploid, hexaploid).

Key Results

Loss of self-incompatibility was associated with both intercontinental dispersal and genome duplication. European plants were largely self-incompatible, whereas North American plants were intermediately to fully self-compatible. Within both European and North American populations, loss of self-incompatibility increased as ploidy increased. Ploidy change and intercontinental dispersal both contributed to loss of self-incompatibility in North America, but range expansion did not affect self-incompatibility within Europe or North America.

Conclusions

When species are subject to population bottlenecks arising through multiple factors, each factor can contribute to self-incompatibility loss. In a widespread polyploid complex, the loss of self-incompatibility can be predicted by the cumulative effects of whole-genome duplication and intercontinental dispersal.

Methods

We performed paired (i.e. both performed on the same maternal plant) self- and outcrosses on a series of Campanula rotundifolia plants from 24 populations across the European and North American ranges. Each pair was then used to calculate a ratio of selfed seed to outcrossed seed, which was in turn used to calculate an Index of Self-Incompatibility (1-ratio). We also assigned the ploidy level and location (Europe vs. North America) as discrete values.

We then calculated the linear distance from each population to a hypothesized origin in the Czech Republic. While it is now suspected that the origin is farther south (which was determined after the publication of this paper), that difference does not change the outcome of the analyses in this paper.

The dataset included here contains the following data columns: Population ID (which corresponds to the supplemental data file), Ploidy (2X, 4X, or 6X), Continent (1 = Europe, 2 = North America), Distance from origin (km), Selfed_seed (number of selfed seed), Outcrossed_seed (number of outcrossed), and Ratio (self/out).

             

Usage Notes

The population numbers referred to in the dataset are listed in the supplemental file available on the AJB website for this article. Localities and coordinates are available there.

Funding

National Science Foundation, Award: DBI‐1461169

National Science Foundation, Award: DEB‐1457686