Dear colleagues,
Biology Thursday seminar continues on today, 12:15pm – live on site, room IT106!
See you soon!
Heikki
Hanna Sigeman from University of Oulu will present her research on:
Evolution of sex chromosomes in Sylvioidea songbirds
Sex chromosomes were discovered more than 100 years ago. They have been studied intensely from a theoretical perspective since then, giving rise to a large body of testable predictions about their evolution from autosomes. Using genome sequencing technology, we can now study the full DNA sequence of sex chromosomes. The analysis of sequence data from a wide range of taxonomic groups has revealed that sex chromosomes are more dynamic and variable than previously believed. Several aspects of sex chromosome evolution, however, remain poorly understood, especially relating to the early stages of evolution from autosomes.
Here, I study the evolution of sex chromosomes across Sylvioidea songbirds using genomic data and bioinformatic methodology. All members of this superfamily have a shared “neo-sex chromosome”: a fusion between an autosome (chromosome 4A) and the existing sex chromosomes. The sex chromosomes of birds (ZW) formed in a common ancestor more than 100 million years ago. Since then, the W chromosome has undergone severe degradation and shortening, obscuring almost all traces of their early evolution. Additions of new genetic material through autosome-sex chromosome fusions, however, allow us to study the early stages of sex chromosome evolution.
I developed a computational pipeline aimed at discovering and visualizing sex chromosomes. I applied this pipeline to genomic data from species belonging to 13 different Sylvioidea families, and found that four additional autosome-sex chromosome fusions have occurred in different lineages within the group (involving chromosomes 3, 4, 5 and 8). These different fused regions have intermediate to extremely low W degeneration levels, with dosage sensitive and evolutionarily constrained genes being retained to a higher degree than other genes. These results shows that Sylvioidea songbirds are an ideal system for testing theory relating to sex chromosome evolution, and that bird sex chromosomes are more variable than previously believed.
More info about Hanna: https://scholar.google.com/citations?user=xqiJ-MoAAAAJ&hl=en
Related research:
Findzx: an automated pipeline for detecting and visualising sex chromosomes using whole‑genome sequencing data. Sigeman et al. 2022, BMC Genomics. https://doi.org/10.1186/s12864-022-08432-9
Whole-genome analysis across 10 songbird families within Sylvioidea reveals a novel autosome–sex chromosome fusion. Sigeman et al. 2020, Biol Lett.
http://dx.doi.org/10.1098/rsbl.2020.0082
Noémie Pichon Post-doctoral researcher University of Oulu, Finland
noemie.pichon@oulu.fimailto:noemie.pichon@oulu.fi