Intercontinental dispersal and whole-genome duplication contribute to loss of self-incompatibility in a polyploid complex.
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.
['Sutherland|Brittany L|BL|', 'Quarles|Brandie M|BM|', 'Galloway|Laura F|LF|']
D029422:Campanulaceae D004171:Diploidy D020440:Gene Duplication D005828:Genetics, Population D018745:Genome, Plant D054817:Pollination D011123:Polyploidy D057945:Self-Fertilization D060436:Self-Incompatibility in Flowering Plants D057891:Tetraploidy
Campanula rotundifolia tetraploid hexaploid Campanulaceae gametophytic self-incompatibility long-distance dispersal mating system polyploidy