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Woodworker1968

Biology question

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Woodworker1968

Is it possible for a species to become extinct or undergo a mass die-off because of a species-wide collapse in its collective genetic viability? Has this ever actually happened?

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DarkStormyKnight

Hi hello! Genetics nerd here.

What do you mean by "genetic viability"? Like everyone going sterile at the same time? It's unlikely to happen to everyone at once since genetic mutations take time to spread throughout the population, and if it's a mutation conferring sterility then it's even more unlikely since those affected can't pass on their genes. So as far as I know, it hasn't actually happened.

Does that help answer your question?

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Memento1

By collective genetic viability, do you mean species that have low genetic diversity because of a past population bottleneck, like the cheetah?  It's certainly a giant concern.

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Leilamy
39 minutes ago, Memento1 said:

By collective genetic viability, do you mean species that have low genetic diversity because of a past population bottleneck, like the cheetah?  It's certainly a giant concern.

If you do mean low genetic diversity like Memento said then yes, I don't have any example at the ready but low genetic diversity can easily lead to extinction or massive death because the population as a whole is more likely to all suffer through epidemics or other perturbations that modify their environnments.

 

If a population is under a certain level, they probably won't be able to bring back up their numbers after a pandemic through evolutionnary rescue for one example.

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daveb

I found this very brief article on genetic viability on wikipedia, and another article on Minimum viable population. If you are going by those definitions and ideas, then I think it's probably safe to say, yes, it has happened that a species became extinct by reaching too low of a population. In fact, that seems to me like it would be pretty common when it comes to extinctions. Large populations are less likely to all die in a catastrophe or epidemic or other single event, but multiple events could whittle them down to the point of being small enough to succumb to a single event (although, that wouldn't really be singular as it was preceded by other events). I think there is good genetic evidence that various species (including humans) have experienced bottle-necks in population size.

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Woodworker1968

What I was wondering was if a species' entire population ended up with just lousy genetics in general, so it ends up crashing them.

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Ace of Mind
33 minutes ago, Woodworker1968 said:

What I was wondering was if a species' entire population ended up with just lousy genetics in general, so it ends up crashing them.

Lousy genetics is sort of a relative term I think. The suitability of the genetics would be determined by the environment and competing species, so its hard to say.
I would also suppose (as a totally non-geneticist computer engineer) that genetics in any individual which are made lousy in the current environment would be increasingly less likely to propagate throughout a species, and so its hard to imagine the whole species somehow having unsuitable genetics. However, I also imagine that there could totally be a sudden change in environment that makes a previously useful set of genes suddenly become a handicap, simply because whatever the species was good at is now no longer what is needed to survive. 

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gisiebob

you might be interested in looking at the history of the banana, whose cultivar was selectively bred to bear sterile fruit (for edible seeds) and and maintains its population with asexual reproduction (yay!) this means that all banana plants have very similar genetics, and the bananas today are not the same as they used to be because a virus was able to monopolize on the genetic similarities between plants and wipe them all out.

 

we don't have a lot of history on the lifeforms that fail genetic diversity class because they by definition find ways to get themselves expelled quite quickly. the imperfect replication factor is kinda baked in for most life as we understand it.

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Memento1

Yeah, genetics are not inherently good or bad, they're relative.  It's about fit to environment.  In order for an entire population to have genetics that are poorly suited to the environment, either the environment had to change (so what used to fit no longer does), or, as I said, the population underwent a bottleneck that left severely limited genetics.

 

I get the feeling you have a specific species in mind...do you?

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