[imakesnowflakes]

Layman here.

Even if the impact on the food chain is zero, does it mean that there won't be other impacts?

For example, on the eradication of mosquitoes, what if the disease that are currently only spread via mosquitoes mutate/evolve themselves to be airborne?

[slapshot]

> what if the disease that are currently only spread via mosquitoes mutate/evolve themselves to be airborne?

Evolution doesn't have an intent. Diseases can't "evolve themselves." Evolution happens through random mutations* and selection of the fittest. If a mutation makes a virus or bacteria or protozoan more likely to survive, then the descendants of the mutant tend to multiply more and become more common. If the mutation makes the organism less likely to survive, descendants of the mutant tend to die out over time. (In other words, no matter how hard you hope your offspring will be born with four arms, they never will be.)

If anything, eliminating mosquitoes will make us SAFER from airborne zika or malaria. Why? Right now, there are tens of millions of infected mosquitoes out there right now. If airborne malaria is possible, there are tens of millions of chances for it to occur every day. And that would be such a powerful disease that it wouldn't matter that there also exists bloodborne malaria. If we eliminate tens of millions of malaria hosts, we reduce the number of chances for malaria to mutate into an airborne form.

As it happens, I don't think airborne malaria is likely -- the life cycle of malaria is way too complex and depends too much on stages that are specific to mosquitoes. https://en.wikipedia.org/wiki/Malaria But the idea is the same.

* And a few other processes, such as DNA exchange, but the effect is the same for this purpose.

[imakesnowflakes]

>Evolution doesn't have an intent. Diseases can't "evolve themselves."

I know. But when you remove mosquitoes from the picture, aren't you putting selection pressure on the diseases to be airborne?

>Evolution happens through random mutations* and selection of the fittest...

Yes. Say a virus of a disease x that normally spreads via mosquitos, gain a mutation to be airborne. But since there are an abundance of mosquitoes, an airborne strain does not have an advantage over mosquitoes borne strain. So it dies off (because of competition)

But when you eradicate the mosquitoes, or reduce their number significantly, suddenly the airborne strain has a tremendous advantage over the mosquito borne strain. Hence it can grow in numbers and eventually completely replace the mosquito borne strain...

Isn't this even remotely possible?

[saalweachter]

> I know. But when you remove mosquitoes from the picture, aren't you putting selection pressure on the diseases to be airborne?

Organisms also need the opportunity to evolve; removing their only vector is analogous to trying to apply selective pressure to pigs to evolve to fly by throwing them off a cliff. Yes, any pig who could fly would survive and have a huge advantage over all the now-dead non-flying pigs. But it just ain't gonna happen.

[imakesnowflakes]

That would be true if you are going to eradicate mosquitoes overnight...

Also, I am just putting forward one possibility other than the effect on the food chain...

[slapshot]

> aren't you putting selection pressure on the diseases to be airborne?

> an airborne strain does not have an advantage over mosquitoes borne strain

There are hundreds of millions of people today who don't currently have malaria, but would be at risk to get malaria if it went airborne. Airborne malaria wouldn't be competing with mosquitoborne malaria. It'd be competing with running out of people to kill.

There seems to be a startup lesson here: your competition isn't legacy players. It's non-consumption.

[imakesnowflakes]

Sorry. I have no idea what you are talking about.

Are you a biologist/ecologist or someone knowledgeable in the field?

[jessaustin]

Instead of asking for credentials, just think a little harder. If "airborne malaria" could possibly be a thing, it would already be a thing. Plasmodium isn't a work crew responsible for killing a given number of people every year, after which they relax for a bit, only getting really creative when they fall behind their quota. It is a reproducing species that will reproduce and thrive as much as possible. There is no intelligence guiding mutation. If flying were an option, Plasmodium would be flying.

Your question is like asking, "if we rounded up all the lions in Africa and put them in pens, would they evolve wings to escape?" Yes it's that silly.

[imakesnowflakes]

Sorry. I have to ask this to you also. Are you a biologists/ecologists or some one knowledgable in the field?

[jonnathanson]

(I'm a layperson, too, for the record.)

"I know. But when you remove mosquitoes from the picture, aren't you putting selection pressure on the diseases to be airborne?"

Not necessarily that specific pressure. Except in carefully controlled laboratory situations, we can't specify the selection pressure being applied. There are too many potential pressures at work, and the mutation outcomes are too stochastic. At best we can force pressure in general. The outcome of that pressure might be entirely different from what we expect it to be.

Let's say we eradicate mosquitos. What other vectors of transmission does a virus like Zika have? What other hosts? It's possible the virus finds a new insect-borne transmission pathway: say, ticks instead of mosquitos. It's possible the virus 'focuses' (to use the term very very loosely) on other hosts, and effectively ceases to be a human concern. I'd wager that either of these outcomes is the more likely adaptation case than a leap to airborne transmission.

Evolving an entirely new means of infectious transmission seems to be a much rarer adaptation than adapting through other means (increased infectious potential; severity of infection; adaptation to new host types; etc.). It's popular in TV and movies to speak about a virus "going airborne," but in actual record, that's usually not what happens. Evolution doesn't have any agency or self-direction; it usually arrives at the 'laziest' and least costly alternative in response to imposed pressures. In this scenario, evolving airborne survivability and transmissibility is probably more costly than adapting to whatever enzyme prevents fleas and ticks from being carriers.

Source: http://evolution.berkeley.edu/evolibrary/news/141003_ebola

[inimino]

There seems to be a mixup here between "pressure" as in "this organism is under pressure" (implying an unfavorable environment) and selection pressure, which acts on genes, not species, and is really more of a filter.

It's not as if an organism can "release" the "pressure" by evolving in a new direction. In your example, if we eradicate mosquitos, one transmission vector becoming less viable doesn't make other vectors more likely to arise, as if by some conservation of total population.

> least costly alternative in response to imposed pressures

Evolution is even lazier, alternatives don't arise in response to imposed pressures at all, so in this scenario the lazy thing is extinction.

[imakesnowflakes]

So it seems that it is unlikely, but not entirely impossible.

Also, I am just putting forward a dangerous possibility other than the effect on the food chain..

[ThrustVectoring]

Evolution does not work that way. Parasites are generally happy to keep on reproducing until their host dies - there's no reason for them to stop, since the only reasoning that evolution understands is "there tends to be more things that reproduce better". Malaria reproduces better by going through human hosts and mosquito carriers than by going airborne. If going airborne helped an individual generation of malaria, malaria would already be airborne.