1 research outputs found
Evolution of human gene expression
During evolution, biological differences between species can arise not only due
to structural differences between genes, but also following changes in how,
where and when genes are active. However, we know much less about this
second aspect, because large-scale comparative transcriptomics only became
feasible relatively recently. In this thesis, I will therefore investigate several
aspects of gene expression evolution, with emphasis on our own species.
A first step to understanding regulatory evolution is to determine how
variation in gene expression is created. Transposable elements (TEs) are
genomic parasites that can affect their host genome in a number of ways,
including gene expression. In Chapter 2, I investigate to what extent
transposable elements (TEs) have contributed to expression differences between
humans and chimpanzees.
Once expression variation has been established, a combination of selection and
drift will decide which variants are passed on to future generations. It is of
particular interest to identify changes that were established through positive
selection, as these are adaptive. In Chapter 3, I describe a new method to detect
positive selection acting on gene expression and apply it to data from humans
and chimpanzees.
Human gene expression is regulated through several mechanisms associated
with transcription and post-transcriptional processing. In Chapter 4, I consider
the long-term evolution of the human genome and investigate whether genes
have reached their maximum capacity in terms of regulatory complexity.
Finally, in Chapter 5, I explore the relationship between gene regulation and
sequence conservation by identifying and analysing extremely conserved
elements in the genome of the fruit fly Drosophila melanogaster