De novo transcriptome assembly and sex-biased gene expression in the cyclical parthenogenetic Daphnia galeata

Huylmans, Ann K and López Ezquerra, Alberto and Parsch, John and Cordellier, Mathilde (2016) De novo transcriptome assembly and sex-biased gene expression in the cyclical parthenogenetic Daphnia galeata. Genome Biology and Evolution, 8 (10). pp. 3120-3139. ISSN 1759-6653

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Daphnia species have become models for ecological genomics and exhibit interesting features, such as high phenotypic plasticity and a densely packed genome with many lineage-specific genes. They are also cyclic parthenogenetic, with alternating asexual and sexual cycles and environmental sex determination. Here, we present a de novo transcriptome assembly of over 32,000 D. galeata genes and use it to investigate gene expression in females and spontaneously produced males of two clonal lines derived from lakes in Germany and the Czech Republic. We find that only a low percentage (18%) of genes shows sex-biased expression and that there are many more female-biased gene (FBG) than male-biased gene (MBG). Furthermore, FBGs tend to be more conserved between species than MBGs in both sequence and expression. These patterns may be a consequence of cyclic parthenogenesis leading to a relaxation of purifying selection on MBGs. The two clonal lines show considerable differences in both number and identity of sex-biased genes, suggesting that they may have reproductive strategies differing in their investment in sexual reproduction. Orthologs of key genes in the sex determination and juvenile hormone pathways, which are thought to be important for the transition from asexual to sexual reproduction, are present in D. galeata and highly conserved among Daphnia species.

Item Type: Article
DOI: 10.1093/gbe/evw221
Subjects: 500 Science > 570 Life sciences; biology > 576 Genetics and evolution
Research Group: Vicoso Group
SWORD Depositor: Sword Import User
Depositing User: Sword Import User
Date Deposited: 10 Nov 2016 08:05
Last Modified: 05 Sep 2017 09:08

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