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Abstract Detail


Population Genetics

Weingartner, Laura [1], Harkess, Alex [2], Brown, Jennifer [2], Moore, Richard [2].

Contrasting patterns of polymorphism and divergent on the Carica papaya X and Y chromosomes.

The sex chromosomes of the tropical crop papaya (Carica papaya) are young and consequently allow for the examination of evolutionary forces that affect early sex chromosome formation. We sequenced six X/Y gene pairs and 12 autosomal gene pairs from 42 papaya accessions from natural populations and analyzed the data for molecular signatures of selection. In most sex chromosome systems, the Y chromosome displays significantly reduced polymorphism levels while the X chromosome maintains a level of polymorphism comparable to autosomal loci. However, the four papaya sex-linked loci that we examined display diversity patterns that oppose this trend. The X alleles exhibit significantly reduced polymorphism levels while the Y alleles maintain expected or greater than expected levels of diversity. Molecular population genetic analyses suggest that genes on the X associated with male function have undergone selective sweeps. Conversely, we find evidence of divergent haplotypes on the Y that extend across the bulk of the non-recombining region of the Y. We hypothesize that the X chromosome has recently undergone a selective sweep while elevated Y polymorphism is due to population structure.

Broader Impacts:


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1 - Indiana University, Jordan Hall, 1001 E Third St., Bloomington, IN, 47405, USA
2 - Miami University, Botany, 316 Pearson Hall, Oxford, OH, 45056, USA

Keywords:
sex chromosomes
dioecy
evolutionary genetics
selective sweep.

Presentation Type: Oral Paper:Papers for Topics
Session: 26
Location: Portland Room/Chase Park Plaza
Date: Tuesday, July 12th, 2011
Time: 10:30 AM
Number: 26010
Abstract ID:324


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