These authors contributed equally to this work.
COMPARATIVE POPULATION GENOMICS IN COLLINSIA SISTER SPECIES REVEALS EVIDENCE FOR REDUCED EFFECTIVE POPULATION SIZE, RELAXED SELECTION, AND EVOLUTION OF BIASED GENE CONVERSION WITH AN ONGOING MATING SYSTEM SHIFT
Article first published online: 11 JAN 2013
© 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.
Volume 67, Issue 5, pages 1263–1278, May 2013
How to Cite
Hazzouri, K. M., Escobar, J. S., Ness, R. W., Killian Newman, L., Randle, A. M., Kalisz, S. and Wright, S. I. (2013), COMPARATIVE POPULATION GENOMICS IN COLLINSIA SISTER SPECIES REVEALS EVIDENCE FOR REDUCED EFFECTIVE POPULATION SIZE, RELAXED SELECTION, AND EVOLUTION OF BIASED GENE CONVERSION WITH AN ONGOING MATING SYSTEM SHIFT. Evolution, 67: 1263–1278. doi: 10.1111/evo.12027
- Issue published online: 25 APR 2013
- Article first published online: 11 JAN 2013
- Accepted manuscript online: 11 DEC 2012 02:14PM EST
- Manuscript Accepted: 15 NOV 2012
- Manuscript Received: 13 JUL 2012
- University of Toronto Department of Ecology and Evolutionary Biology Postdoctoral fellowship
- National Science Foundation for awards. Grant Numbers: DEB 0324764, DEB 0709638
- efficacy of selection;
- mating system;
- next-generation sequencing;
Selfing species experience reduced effective recombination rates and effective population size, which can lead to reductions in polymorphism and the efficacy of natural selection. Here, we use illumina transcriptome sequencing and population resequencing to test for changes in polymorphism, base composition, and selection in the selfing angiosperm Collinsia rattanii (Plantaginaceae) compared with its more outcrossing sister species Collinsia linearis. Coalescent analysis indicates intermediate species divergence (500,000–1 million years) with no ongoing gene flow, but also evidence that the C. rattanii clade remains polymorphic for floral morphology and mating system, suggesting either an ongoing shift to selfing or a potential reversal from selfing to outcrossing. We identify a significant reduction in polymorphism in C. rattanii, particularly within populations. Analysis of polymorphisms suggests an elevated ratio of unique nonsynonymous to synonymous polymorphism in C. rattanii, consistent with relaxed selection in selfing lineages. We additionally find higher linkage disequilibrium and differentiation, lower GC content at variable sites, and reduced expression of genes important in pollen production and pollinator attraction in C. rattanii compared with C. linearis. Together, our results highlight the potential for rapid shifts in the efficacy of selection, gene expression and base composition associated with ongoing evolution of selfing.