GENETIC ARCHITECTURE OF SEXUAL DIMORPHISM IN A SUBDIOECIOUS PLANT WITH A PROTO-SEX CHROMOSOME
Article first published online: 30 NOV 2010
© 2010 The Author(s). Evolution© 2010 The Society for the Study of Evolution.
Volume 65, Issue 4, pages 1114–1126, April 2011
How to Cite
Spigler, R. B., Lewers, K. S. and Ashman, T.-L. (2011), GENETIC ARCHITECTURE OF SEXUAL DIMORPHISM IN A SUBDIOECIOUS PLANT WITH A PROTO-SEX CHROMOSOME. Evolution, 65: 1114–1126. doi: 10.1111/j.1558-5646.2010.01189.x
- Issue published online: 4 APR 2011
- Article first published online: 30 NOV 2010
- Accepted manuscript online: 10 NOV 2010 02:11AM EST
- Received July 21, 2010, Accepted October 27, 2010
- genetic correlations;
- sex chromosome
The rise of sexual dimorphism is thought to coincide with the evolution of sex chromosomes. Yet because sex chromosomes in many species are ancient, we lack empirical evidence of the earliest stages of this transition. We use QTL analysis to examine the genetic architecture of sexual dimorphism in subdioecious octoploid Fragaria virginiana. We demonstrate that the region housing the male-function locus controls the majority of quantitative variation in proportion fruit set, confirming the existence of a proto-sex chromosome, and houses major QTL for eight additional sexually dimorphic traits, consistent with theory and data from animals and plants with more advanced sex chromosomes. We also detected autosomal QTL, demonstrating contributions to phenotypic variation in sexually dimorphic traits outside the sex-determining region. Moreover, for proportion seed set we found significant epistatic interactions between autosomal QTL and the male-function locus, indicating sex-limited QTL. We identified linked QTL reflecting trade-offs between male and female traits expected from theory and positive integration of male traits. These findings indicate the potential for the evolution of greater sexual dimorphism. Involvement of linkage groups homeologous to the proto-sex chromosome in these correlations reflects the polyploid origin of F. virginiana and raises the possibility that chromosomes in this homeologous group were predisposed to become the sex chromosome.