Abstract Detail



Comparative Genomics/Transcriptomics

Carey, Sarah [1], McDaniel, Stuart [2].

Ancient sex chromosome systems in plants.

Sex chromosomes have evolved several times across the tree of life. The bryophytes, whose ancestor is thought to have been dioecious, provide novel systems for understanding the evolution of ancient sex chromosomes. Given their haploid dominant nature, sex in dioecious bryophytes is determined by a UV sex chromosomal system. In this system, each sex has a non-recombining chromosome (U for females and V for males) that pair at meiosis in the monomorphic sporophyte and segregate to the male and female, haploid gametophytes. Because the sex chromosomes are transcriptionally active in the haploid stage and therefore subject to purifying selection we expect many orthologous genes will be retained between the U and V chromosomes. Here we use known sex-linked genes in bryophytes to determine the age of their sex chromosomes. We accomplish this by building gene trees, which allow us to determine not only the age of the genes on the sex chromosomes but also whether multiple capture events have occurred. Genes that are sex-linked show clear, monophyletic clusters with the known U and V-linked genes. We find that bryophyte sex chromosomes are ancient with multiple capture events of genes throughout their evolution. We additionally use these gene trees to test the of accuracy of ancestral state reconstructions of dioecy in the bryophytes.


1 - University of Florida, Department of Biology, Gainesville, FL, 32611, USA
2 - Biology Department, Gainesville, FL, 32611, United States

Keywords:
Sex chromosomes
Bryophytes.

Presentation Type: Oral Paper
Number:
Abstract ID:411
Candidate for Awards:Margaret Menzel Award


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