Lecture 21. Applied Evolutionary Genetics Flashcards
What do gene trees do not always match ?
Species tree
What is a gene and a species tree that matches called ?
Concordant
What is incomplete lineage sorting ?
If the time between the two divergences is short and the population is large neither allele may reach fixation before the next split
What is another way to describe incomplete lineage sorting ?
Retention of ancestral polymorphism through speciation events
What are gene trees and species trees that do not match called ?
Discordant
What is an example of incomplete lineage sorting ?
Modern and archaic human population
What would prevent the number of discordant gene trees that place non-African with Neanderthal equaling the number that place African with Neanderthal ?
Gene flow has increased the number of gene trees that group Non-African with Neanderthal
What is introgression ?
The transfer of genetic material between species or subspecies through horizontal event followed by backcrossing with the parental species
What can be used to detect and measure gene flow ?
Deviations from simple phylogenetic expectation
Why do present day Eurasians show less Neanderthal ancestry than prehistoric Eurasians ?
Neanderthals carried more deleterious variants due to long-term small population sizes and inbreeding. Neanderthal ancestry was associated with reduced fitness
What are many human diseases caused by ?
Mutations in single genes
What is haploinsufficiency ?
One functional allele insufficient to get the job done
What is dominant negative mutation ?
Faulty protein is produced and interferes with the wildtype allele’s function
Roughly, how many de novo mutations does a newborn carry ?
75
What is a major source of mutation ?
DNA replication
What varies between males and females ?
Germline replications
What do both sexes undergo by onset of puberty ?
A similar number of mitotic cell divisions
What do males have after puberty ?
About 23 replications per year because of frequent mitotic divisions of spermatogonial stem cells
What do older fathers pass on to their offspring ?
More mutations
What are some regions of the genome ?
Inherently less stable and therefore more prone to mutation
What can duplicated regions of the genome do ?
Can confuse replication and recombination machinery, leading to mutation, including deletions and further duplication
Where is the olduval protein domain found ?
Found repeated in NBPF genes involved in neuronal development
Where are NBPF genes experienced ?
In rapid duplications in ancestors of monkeys
What are more copies of the NBPF genes associated with ?
Larger brain sizes and lobe surface areas
What is the correlation of NBPF ?
Copy number and mathematical aptitude in humans
How have high regions of olduval repeats effected regions with NBPF ?
Made them unstable and prone to further duplication or deletion
What diseases has the instability linked to NBPF caused ?
- Schizophrenia
2. Autism
What increases the frequency of both common and rare recessive traits ?
Close inbreeding
What can increase the frequency of recessive disease alleles ?
- Founder effects
2. Bottlenecks
What happens with genetic drift in smaller populations ?
It is stronger and selection cannot act as effectively
How will disease variants that only have a minor fitness act ?
The impact will persist longer
What is required to push individual over disease threshold ?
Multiple risk alleles
What is the effect size of a risk allele ?
The size of contribution it has to your risk of developing the disease
What will the most common low effect risk alleles be ?
Selectively neutral or have low selection coefficients
