Population genetics in Ceratodon purpureus

This project is aimed at understanding the evolutionary forces that shape variation within and among populations using the moss Ceratodon purpureus.

C. purpureus is a common, dioicous, and highly variable species found on disturbed soils throughout temperate regions of the world. Molecular variation in the species shows little geographic structure, presumably due to frequent migration among populations (McDaniel and Shaw 2005). The species is also easy to grow in culture, making it well suited for experimental studies. Previous experiments have focused on adaptation to heavy-metal- contaminated soils (Shaw, Jules, and Beer 1991; Jules and Shaw 1994), sexual dimorphism (Shaw and Gaughan 1993), detecting epistatic variance for life history traits (Shaw, Weir, and Shaw 1997), and contrasting within- and among-population life history variation (Shaw and Beer 1999).

Stuart McDaniel, a graduate student in the lab, recently received an NSF Dissertation Improvement Grant to conduct a quantitative trait locus (QTL) mapping experiment to dissect the genetic basis of life history variation among populations. An unexpected result was the discovery of partial reproductive isolation between a temperate and tropical population of C. purpureus, apparently caused by negative epistatic interactions among four major loci. Ongoing work on the project includes testing whether the hybrid breakdown is a byproduct of adaptive evolution. Kim Ryall, a graduate student in the lab, is investigating the utility of C. purpureus for experimental work into the biology of interactions between bryophytes and their fungal endophytes.

References:

McDaniel, SF. Genetic correlations do not constrain the evolution of sexual dimorphism in the moss Ceratodon purpureus. Evolution 59(11): 2353-2361. reprint

McDaniel, SF and AJ Shaw. 2005. Selection and intercontinental migration in the cosmopolitan moss Ceratodon purpureus, (Hedw.) Brid. Molecular Ecology 14:1121-1132. reprint

Shaw A.J. & S.C. Beer. 1999. Life history variation in gametophyte populations of the moss Ceratodon purpureus (Ditrichaceae). American Journal of Botany 86:512-521. reprint

Jules, E.S. and A.J. Shaw. 1994. Adaptation to metal-contaminated soils in populations of the moss, Ceratodon purpureus: vegetative growth and reproductive expression. American Journal of Botany 81:791-797. reprint

Shaw A.J. & J. M. Gaughan. 1993 Control of sex ratios in haploid populations of the moss, Ceratodon purpureus. American Journal of Botany 80: 584-591. reprint

Shaw A.J. & E. S. Jules, and S. C. Beer. 1991 Effects of metals on growth, morphology, and reproduction of Ceratodon purpureus. Bryologist 94: 270-277. reprint

Shaw A.J. & B. S. Weir, and F. H. Shaw. 1997 The occurrence and significance of epistatic variance for quantitative characters and its measurement in haploids. Evolution 51: 348-353. reprint

The drawings of male and female Ceratodon plants were made by Chaz Zartman.

 Shaw Laboratory
 139 Biological Sciences Bldg.
 Box 90338
 Department of Biology
 Duke University
 Durham
 North Carolina 27708
 U.S.A.

 Phone: (+1) 919 660-7345
 Fax: (+1) 919 660-7293