Mcdonald krietmen test!
Evolution of new genes
M-K test looked at ! Fixed! Polymorphic!
synonymous (silent)! !
! 7 2
Non synonymous (replacement)
NF/SF = NP/ SP!
Chi squared = N (ad-bc)2!
Polymorphism ( variation within species)! 8! 3!
! 20 8
Divergence ( variation between species) Neutral region! Test region 2!
Polymorphism! ! !
Will not allow any mutation at all so essential for the
- similar to a qtl!
The peak tells us that we should
sequence this region in a variety of
individuals from population and also
assess their phenotype!
-predict these with increased longevity
would have deft sequences in this region
than those with short life spans.
The origin of new genes
Pagel and pomiankowski ch 3!
-syllabus revised lecture schedule blackboard!
- review paper on positive selection
Original view was that new genes always arose from duplication!
- it is not exclusive!
The best way to study evolution of new genes is to ﬁrst identify recently eveolved genes and
then infer their origin!
- drosophila -jingwei (long and langley 1993 science)!
- jingwei is a fusion of two parental genes: - ymp yellow emperor and -adh!
- d yakuza and d teisseri!
- jingwei is -retroposition of adh mrna plus exons and introns from ymp!
- new duplicate under very strong positive selection!
- digestive system of leaf eating colobine monkeys (zhang et al 2002, nature genetics) RNAse1 - degrading double stranded RNA!
-max efﬁciency at pH 7.4!
-RNAse1B - max efﬁciency of pH 6 (pH of colobine gut) !
- 9 substitutions between 1 and 1B!
-site directed mutagenesis!
-7/9 substitutions found that it reduces its degrading efﬁciency so their thought is
then... Adaptive changes have come at the expense of efﬁciency (relative to the
How can we get new genes?!
- Gene Duplication - whole genomes!
- segmental duplication