Abstract Detail

Genetics Section

Payton, Adam [1], Mcdaniel, Stuart [2], Szoevenyi, Peter [3].

Evolution of sex chromosomes in Ceratodon purpureus.

Non-recombining sex chromosomes are predicted to expand as they accumulate alleles beneficial to each sex. However, non-recombining regions are widely observed to degenerate due to their reduced capacity to fix adaptive mutations and purge deleterious ones. To investigate the evolution of non-recombining sex chromosomes, we studied patterns of molecular evolution on the large heteromorphic UV sex chromosomes of the model moss Ceratodon purpureus. In this species approximately one third of the genome is found within the recombination suppressed sex chromosome. Analysis of sex linked loci found in both males and females suggest this region of suppressed recombination has undergone several expansions. To evaluate the effects after incorporation into the sex determining region we used Illumina based genotyping by sequencing of 96 individuals from a mapping population to identify thousands of sex linked loci. These loci were used to probe the transcriptome, genes with both male and female homologs were compared to evaluate the effects of suppressed recombination. We found a significant elevation in the number of synonymous and non-synonymous mutations in sex-linked genes compared to autosomal genes, females also experienced an increased use of sub-optimal codons. All indicating deleterious effects to genes once incorporated into the area of suppressed recombination. Yet, approximately half of the homologous genes identified showed evidence of recent acquisition into the recombination suppressed sex determining region of the chromosome. This pattern may be driven by a tradeoff between the short term gain of a beneficial sex specific allele or locally adapted allele but ultimately results in the degradation of the surrounding genes due to the lack of recombination.

Broader Impacts:

1 - University of Florida, Biology, Gainesville, FL, 32611, USA
2 - University of Florida, Biology Department, Gainesville, FL, 32611, USA
3 - University of Zurich, Institute of Evolutional Biology and Environmental Science, Zurich, Switzerland

Keywords:
sex chromosomes
genotyping by sequence.

Presentation Type: Oral Paper:Papers for Sections
Session: 6
Location: Marlborough B/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 10:15 AM
Number: 6006
Abstract ID:781
Candidate for Awards:None