The evolution of each
different species of living organisms mainly operate from the mechanism of
natural selection, in which the individuals better adapted to their
environments tend to survive and produce more offspring over other individuals as
each generation passes. However, existing
in some of these organisms are what are called “selfish genes”, genes that have
the ability to be exist along each generation of a species without providing
any advantage to the said organisms.
There are particular fungi
that carry the gene selfish gene called “spore killer”. Related sibling fungal spores that do not
carry this gene are all killed by the spore carrying the gene. As a result, there will not be as many individuals
to exist in future generations of a fungus such as this, while the spore
killing gene continues to be passed along the individuals of every following
generation. Different unique forms of
selfish genes killing their siblings have existed in other species as well in
fruit flies and mice to name a few.
However, it a sperm destroying sibling sperms in those aspects. In mosquitos, selfish genes operate similar
to pesticides in that the individuals that have malaria can have selfish genes
that make it so that only one sex of individuals are born, shrinking their population
size. However, there is still very
little known about the function and spread of selfish genes.
Recently, Uppsala University’s
Department of Systematic Biology researchers succeeded in sequencing complete
genomes that contain complex selfish genes from two different spore killers in
ascomycete fungus, Neurospora intermedia.
It has been learned that spore killing genes exist in chromosome regions
where chromosome has changed direction: forming so called “inversions”. Expanding repetitive DNA and numerous new
mutations were also in these same chromosome regions. This may be the reason these spore killing
genes are unusual in Neurospora intermedia, and it can also be theorized that
the individuals with these genes are more poorly adapted.
Interestingly, the two spore
killers use different genes to kill their respective siblings. Even more surprising was the two spore
killers having no relation to each other.
It could mean that selfish genes including spore killing genes as well
are more common. I believe this is
important because understanding the function of selfish genes would give us a
better understanding of more general evolutionary patterns.
For additional information,
refer to the original article.
For additional information,
click the link of the journal about the genome sequences of the two spore killers.
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