Genomic architecture of Triops cancriformis sex chromosomes in response to sexual system transition

Orr, David Thomas

Biological sciences
September 2017

Thesis or dissertation

© 2017 David Thomas Orr. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.

Sexually antagonistic selection has been suggested to be a leading factor in the reduction of intralocus sexual conflict and driver of sex chromosome evolution. Although the scarcity of empirical data makes it difficult to quantify the impact sexually antagonistic selection has on sex chromosome evolution. Triops cancriformis, have gonochoric and androdioecious (hermaphrodites and rare males) populations giving us a unique opportunity to assess the impact of sexually antagonistic selection across different sexual systems with different pressures of sexual conflict. We aim to characterise sex chromosome structure, differentiation and gene content in T. cancriformis populations with different sexual systems. We used paired-end RAD sequence data of 47 different individuals from two populations (gonochoric and androdioecious), in combination with two new genomic assemblies of T.cancriformis. We increase the number of putative sex linked genetic markers from 52 to 79, finding 18 contigs that are sex linked in both populations to a high confidence level. We accurately characterised the sex chromosome, determining that the sex chromosomes are most likely homomorphic. We find a smaller region under recombination suppression in the androdioecious population, divergent Z chromosomes between populations and determine two different lineages of W chromosome present in the androdioecious population. We also show evidence of a possible recombination event in the androdioecious population and determine a panel of genes that could be involved in sex determination.

School of Environmental Sciences, The University of Hull
Gómez, Africa; Hahn, Christoph
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