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Genome Evolution

Why is this relevant to the study of evolutionary biology of animals?
1. It tells us what we might expect evolution to do:
The limits of how a genome can change ultimately constrain what evolutionary changes
can take place and how fast it can occur.
2. It helps…

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Selection against the rare codon is greatest in highly expressed genes, but weak or nonexistent in
rarely expressed genes (because there is less opportunity for natural selection to act on rarely
expressed genes).

A single gene leads yeast cells to cooperate against threats.
A social behaviour that mobilises yeast cells…

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Evolution has constrained the amino acids used for 360 million years.

Duplication of entire genomes is common in plants but rare in animals.
One case where it has occurred is X. laevis (African toad) which is tetraploid.
This is thought to have arisen after duplication of the entire genome of…

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An example of gene conversion: Saccharomyces cerevisiae has two mating type alleles.
Each individual has a `master copy' of each allele, plus a working copy.
The working copy can be removed and replaced with the other type by using one of the master copies
as a template = mating type…

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o Transposable elements provide the necessary matches

Virogene ­ a strain found in baboons is very similar to that in cats.
Cats and baboons are not thought to be closely related, so this result suggests that there has been
horizontal gene transfer between the two.

Horizontal gene transfer occurred from…

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E.g. a paper shows that Buchnera endosymbiotic bacteria of aphids have stopped their rapid
evolution.
However we don't know the genome has stayed still, we only know no changes have persisted.

Pleiotropy (when one gene influences many traits) limits the types of genetic changes that can occur.
E.g. the melanocortin…

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