ausblenden:
Schlagwörter:
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Zusammenfassung:
The fraction of novel genes tends to be higher in phylogenetically isolated species such as Pristionchus pacificus. Till recently, Caenorhabditis elegans was the closest neighbor of P. pacificus with sequenced genome data, and these two species diverged approximately 75 mya. We found that more than one-third of the P. pacificus genes are orphans and another one-third are duplicates of C. elegans, genes. On one hand, such high numbers make it imperative that these novel genes are investigated, on the other hand, the lack of genomic sampling of neighboring species obviate the possibility of an in-depth analysis. To overcome this issue, we created a unique ladder-like phylogeny around P. pacificus by sequencing the genomes of seven Pristionchus species and two outgroup species. This facilitated age estimation of taxon-restricted genes and shed some light on their chromosomal localization and evolutionary trajectories. Further, we were also able to create a high-confidence candidate set which illustrated six different mechanisms of novel gene origins in Pristionchus nematodes. However, even at such a fine level of taxonomic- resolution, we were unable to trace the origin of a large fraction of novel genes. This inspired us to study novel gene evolution at the microevolutionary level and thus we sequenced the genomes of seven strains of P. pacificus, which allowed us to trace the homology of 99% of all genes either at the species level or at the strain level. The resulting phylogenomic framework has furthered our knowledge of gene and genome evolution of Pristionchus nematodes. In my presentation, I will introduce our most recent findings and share the immense benefits of creating a proper phylogenetic context to investigate the evolution of novel genes.
