@phdthesis{19386,
  abstract     = {Crustaceans are a large group of arthropods with a great diversity of species and
different types of sex determination systems and reproductive modes (Subramoniam, 2017).
This makes them a great model for exploring the evolution of sex chromosomes and sexual
dimorphism and investigating the evolutionary mechanisms driving and maintaining the
diversity of reproductive systems. Within this taxon, Brine shrimp of the genus Artemia, a
branchiopod crustacean, are well suited for such explorations, as they have both highly
dimorphic traits and closely related sexual and asexual species. Although brine shrimp are
known to have ZW sex chromosomes (Bowen, 1963; Parraguez et al., 2009), the sex
chromosomes are still not well characterized at the genomic level, the sex-determination gene
is unknown, and it is still unclear whether the same sex chromosomes as shared by the
different species.
The first part of this thesis was to characterize the Z and W chromosomes in Artemia
using an array of methods, from generating multiple chromosome and contig level genome
assemblies to identifying W-linked scaffolds and transcripts in multiple species using k-mer
based approaches.
The second part tackles the conservation of the cell type specific regulatory pathways
in the female reproductive system between Artemia and Drosophila, and the expression of the
Z-specific region throughout meiosis using single-nucleus RNA-seq data. Our results show
that germline cells lack dosage compensation, with a subset of cells showing evidence of
extreme repression of the Z chromosome.
With multiple sexual species and several asexual lineages of parthenogenetic females
that produce rare males at low frequencies, Brine shrimp present the perfect opportunity to
explore the transition to asexuality and shed light on the prerequisites and repercussions of
the form of modified meiosis maintaining the asexual lineages. The last chapter is an
investigation of the molecular pathways involved in asexual reproduction in Artemia using
newly generated single nucleus RNAseq and WGS data and previously published data. },
  author       = {Elkrewi, Marwan N},
  isbn         = {9783990780534},
  issn         = {2663-337X},
  pages        = {170},
  publisher    = {Institute of Science and Technology Austria},
  title        = {{Evolution of sex chromosomes, sex determination and asexuality in Artemia brine shrimp}},
  doi          = {10.15479/AT-ISTA-19386},
  year         = {2025},
}