Honest question: do parasites evolve, if their hosts do?

[Gottservant]

Hi there,

So this is all about niche, as far as I understand it: a host of a parasite represents a 'niche' that the parasite can adapt for - the question is, if the host evolves, does the parasite therefore have to evolve? Or have the opportunity to evolve?

Clearly there are different selection pressures and in principle they do not represent an impossible burden since the host is able to overcome them, however, there is nothing to say that the parasite won't simply die, because it can't keep up. What are the considerations here?

I would like to think a Creationist can learn from an Evolutionist, but it may come down to an expectation that a Creationist find his own Evolution - why should an Evolutionist put up with Creationists? I am willing to be a parasite, but the odds have to stack up - the odds have to be in favour of 'evolving' (more powerfully, more emphatically) with the current Host, if not another?

What does it mean to go in search of the perfect host? Does it save you from having to evolve, what you are not ready to? Thoughts?

Thanks for your time.

 

[The IbanezerScrooge]

Hi there,

So this is all about niche, as far as I understand it: a host of a parasite represents a 'niche' that the parasite can adapt for - the question is, if the host evolves, does the parasite therefore have to evolve? Or have the opportunity to evolve?

Oh my goodness! I never thought I would see the day! You actually asked a really good question (your poll question and answers not withstanding)!! Like, I mean it totally made sense and was worded pretty good for someone who clearly doesn't understand evolution, but you asked the right question! Bravo!

The answer is YES!! Resoundingly yes!

Parasites evolve with their hosts. A population that jumps species will even evolve differently in tandem with its new host and we can trace the lineages!! We can see this pretty clearly with lice. There are different species based on the host that they infest, so human lice are genetically different from lice that infest other great ape species such as gorillas, but they are genetically related and we can trace the evolution through DNA comparisons to see where the lineages diverge and, get this... they follow very closely to when humans and gorillas (or whatever other primate we're talking about) diverged! They corroborate our genetic divergence timelines! Isn't that incredible!?

Man, what a breakthrough! Continue your journey, Gott! You can do it!

 

[Gottservant]

Man, what a breakthrough! Continue your journey, Gott! You can do it!

You're not going to tell me "only populations" of parasites, can evolve?

 

[The IbanezerScrooge]

You're not going to tell me "only populations" of parasites, can evolve?

I didn't want to split hairs and ruin your moment, but yes, populations evolve. Individuals do not (not from a scientific evolution POV).

 

[Gottservant]

I didn't want to split hairs and ruin your moment, but yes, populations evolve. Individuals do not (not from a scientific evolution POV).

So if there is one parasite, it doesn't evolve, but if there are two parasites, suddenly both of them evolve?

I would rather either parasite begin to evolve, and then the remaining parasite try to catch up...

What's so special about a population? It covers the range of possible selection pressures?

 

[The IbanezerScrooge]

So if there is one parasite, it doesn't evolve, but if there are two parasites, suddenly both of them evolve?

I would rather either parasite begin to evolve, and then the remaining parasite try to catch up...

What's so special about a population? It covers the range of possible selection pressures?

Yes-ish. As long as those 2 produce offspring they, collectively, can evolve, though, to be fair, that lineage would likely die out and go extinct due to a lack of genetic diversity, which answers your question about "what's so special about a population?" You need many variations and "trial runs" of different gene variants on which selection can act to see which ones survive and make it into the next generation, which answers your second question about selection, which is basically, yes, that's it! In short, the more individuals with unique genomes there are interbreeding the more variation and diversity on which selection can work.

 

[LeafByNiggle]

Parasites evolve with their hosts. A population that jumps species will even evolve differently in tandem with its new host and we can trace the lineages!! We can see this pretty clearly with lice. There are different species based on the host that they infest, so human lice are genetically different from lice that infest other great ape species such as gorillas, but they are genetically related and we can trace the evolution through DNA comparisons to see where the lineages diverge and, get this... they follow very closely to when humans and gorillas (or whatever other primate we're talking about) diverged!

Just to fill in a little more, the reason we can estimate the time when they diverged is because apes are covered with hair and so their lice travel freely around the ape body. But humans have thick hair in distinct areas - namely the head and the pubic area. And because of that separation, lice that live in the head hair are genetically different from lice that live in human pubic hair. By measuring the number of mutations between the two species of lice we can estimate how long the two populations have been isolated from each other, and that would be the point at which humans lost a good portion of their body hair.

 

[Job 33:6]

Well this all is kind of the bread and butter of evolution. Parasites evolve to capitalize on hosts without killing them. Hosts evolve to mitigate damages from parasites, perhaps by evolving ways to kill them.

Think about how hard it is at times to kill a mosquito. Sometimes you can't even feel them because they release numbing agents when they bite you. They have evolved this way because it helps keep their activities covert so that their host doesn't smash them.

So yes, it's absolutely true that parasites evolve to compete with their hosts, just as a lion evolves to catch it's ever faster gazelle.

 

[Shemjaza]

Hi there,

So this is all about niche, as far as I understand it: a host of a parasite represents a 'niche' that the parasite can adapt for - the question is, if the host evolves, does the parasite therefore have to evolve? Or have the opportunity to evolve?

Clearly there are different selection pressures and in principle they do not represent an impossible burden since the host is able to overcome them, however, there is nothing to say that the parasite won't simply die, because it can't keep up. What are the considerations here?

I would like to think a Creationist can learn from an Evolutionist, but it may come down to an expectation that a Creationist find his own Evolution - why should an Evolutionist put up with Creationists? I am willing to be a parasite, but the odds have to stack up - the odds have to be in favour of 'evolving' (more powerfully, more emphatically) with the current Host, if not another?

What does it mean to go in search of the perfect host? Does it save you from having to evolve, what you are not ready to? Thoughts?

Thanks for your time.

As a species evolves the species of parasites infecting them will evolve.

Each species forms a part of the others environment so is bound to interact.

Individuals don't evolve and choice isn't involved.

 

[The IbanezerScrooge]

I am cautiously optimistic that Gottservant's lack of further response in this thread means they are pondering the answer to the question asked and having an evolutionary epiphany.

Or, at a minimum, have been spending these past few days buried in evolutionary research about parasites and how they evolve and has learned a great deal about them.

Fingers crossed!

 

[Kylie]

Hi there,

So this is all about niche, as far as I understand it: a host of a parasite represents a 'niche' that the parasite can adapt for - the question is, if the host evolves, does the parasite therefore have to evolve? Or have the opportunity to evolve?

Yes. If a parasite species infects a host species (say, we have a species of worm that typically infests a particular species of fish), then the fish may evolve some way to avoid being parasitised by the worm. Thus, the worm will need to evolve some way of overcoming this defence.

I would like to think a Creationist can learn from an Evolutionist, but it may come down to an expectation that a Creationist find his own Evolution - why should an Evolutionist put up with Creationists? I am willing to be a parasite, but the odds have to stack up - the odds have to be in favour of 'evolving' (more powerfully, more emphatically) with the current Host, if not another?

I have no idea what you are talking about.

You can't speak of "an evolution" the same way you can speak of "a television." Evolution is a process, not an object.

 

[Kylie]

So if there is one parasite, it doesn't evolve, but if there are two parasites, suddenly both of them evolve?

I would rather either parasite begin to evolve, and then the remaining parasite try to catch up...

What's so special about a population? It covers the range of possible selection pressures?

You misunderstand.

Evolution is how the population changes over many generations. No individual creature is going to evolve during its lifetime. But if you look at a creature and then look at that creature's great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great great grandchild, then you'll see some change due to evolution. The more generations there are, the greater the change.

But if you were able to get a fish from 400 million years ago, and somehow keep that fish alive until today, you'd see that the fish's descendants would have evolved through amphibians, reptiles, dinosaurs and to birds. But that fish you took and kept alive for 400 million years would not have changed. It wouldn't have grown feathers, even though that fish's descendants did.

Remember, the changes that evolution causes only happen when a creature has children. Evolution says that the children are very slightly changed from the parent.

 

[Gottservant]

Wait, but you're saying "only populations of hosts evolve"? Will the same populations of parasites ignore the individual host but not the population of hosts? How? What happens to the individual host, when the population of parasites evolves? As soon as the individual host is isolated, its evolution dies?

Is it impossible for parasites that don't kill individual hosts to evolve?

 

[Shemjaza]

Wait, but you're saying "only populations of hosts evolve"? Will the same populations of parasites ignore the individual host but not the population of hosts? How? What happens to the individual host, when the population of parasites evolves? As soon as the individual host is isolated, its evolution dies?

Evolution is only relevant in the population scale. The population of parasites and the population of hosts.

Each individual isn't particularly relevant to the overall trends.

Also, evolution is a process not an object or a trait. Nothing can have "an evolution" and since evolution isn't a living thing, it can't die.

Is it impossible for parasites that don't kill individual hosts to evolve?

Not at all, parasite species can become more or less dangerous... they can even become helpful so that would now be labelled symbiotes.

 

[Gottservant]

Each individual isn't particularly relevant to the overall trends.

Except that it is, if the individual happens to be more responsive to a threatening selection pressure

Also, evolution is a process not an object or a trait. Nothing can have "an evolution" and since evolution isn't a living thing, it can't die.

Except that not dying is an attribute you can only give to an object. Not that I mind, but you are basically using doublespeak.

Not at all, parasite species can become more or less dangerous... they can even become helpful so that would now be labelled symbiotes.

That's interesting: what selection pressure moves a parasite to a symbiote? That it not kill the host and thus survive for longer?

 

[Shemjaza]

Except that it is, if the individual happens to be more responsive to a threatening selection pressure

No, the individual is much more likely to survive and pass on their genes... but it's still more about statistical likelihood over all.

For example an individual antelope could have a new trait that doubles their chance of getting away from predators... but a random fluke could still lead this antelope as being in exactly the wrong place at the wrong time and get caught by a lioness.

Except that not dying is an attribute you can only give to an object. Not that I mind, but you are basically using doublespeak.

Not true. For something to be able to die it has to first be alive.

That's interesting: what selection pressure moves a parasite to a symbiote? That it not kill the host and thus survive for longer?

Either can be a viable tactic for a species... in general it's typically about short term versus long term gain and that depends on the environment and the supply of hosts.

 

[Mr Laurier]

So if there is one parasite, it doesn't evolve, but if there are two parasites, suddenly both of them evolve?

No.
Parasites are never found as one, or two.
They are found in the dozens at least. And the hundreds or thousands more often.

 

[Bungle_Bear]

No.
Parasites are never found as one, or two.
They are found in the dozens at least. And the hundreds or thousands more often.

It's very rare for humans to have more than one or two tapeworms.

 

[Mr Laurier]

It's very rare for humans to have more than one or two tapeworms.

ah.

 

[Gottservant]

I finally worked out the direction this thread should take - it was suggested that I was making progress: but I couldn't see how (now I do).

It seems we have established that parasites evolve with their hosts; the question is "Can parasites predict the Evolution their host will make?"

My position is, "they should be able to, based on reference to past adaptations, current environment, and known selection pressures"?