Recombination as the driver of genome evolution Flashcards
type of recombination which can lead to aneuploidy
pericentric crossover at the centromeres
how is recombination distributed in human chromosomes?
more at the telomeres- similar but less extreme pattern in mice
distribution of recombination in drosophila
no real correlation
Heterochiasmy
when there is a different distribution of chiasmata locations in males and females
what factors can affect recombination rate?
○ Openness of chromatin
○ Location of centromeres and telomeres
○ Presence of inversions
○ Density of hotspots
○ Temperature (next slide)
○ Chromosome size (the smaller the chromosome, the higher is recombination)
○ Sex (in many species more recombination occurs in female meiosis)
○ Type of meiosis
Chiasmatic vs achiasmatic
recombination and temperature
more recombination seems to occur at non-optimal temperatures
recombination and chromosome size
recombination is more frequent on smaller chromosomes
recombination and sex
as the y chromosome is smaller, there is relatively more recombination
biased gene conversion
preferential fixation of a particular allele often involves GC bias
isochore
region of DNA with an abnormal GC%
features of GC rich regions
higher gene density
higher compactness
earlier replication timing
higher recombination rate
GC content and chromosome size
GC content tends to be higher on smaller chromosomes- e.g. microchromosomes which are common in non-mammalian vertebrates
GC content along the chromosome in mice
much higher at the centromeres
recombination and mutation
recombination seems to be mutagenic- higher nucleotide diversity when there is more exchange
>can be mapped by looking at parents and children
recombination and selection
more recombination - less far reaching impact of a selective sweep in the genome
