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How do you explain stasis in evolution?

janesix
Posts: 3,466
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4/4/2015 5:10:35 PM
Posted: 1 year ago
How do ants stay the same for hundreds of millions of years?

Shouldn't organisms be changing more? Why do some change rapidly and often, while others stay the same for tens of millions of years or more?
RuvDraba
Posts: 6,033
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4/5/2015 2:21:32 AM
Posted: 1 year ago
At 4/4/2015 5:10:35 PM, janesix wrote:
How do ants stay the same for hundreds of millions of years?
Shouldn't organisms be changing more? Why do some change rapidly and often, while others stay the same for tens of millions of years or more?

Insects are one of the most diverse classes of animals in the world, Jane. There are an estimated six to ten million extant species, of which some 12,000 species alone are ants. This compares to about 10,000 extant bird species, and about 5,516 mammal species. So ignoring all the other insects, there are more ant species alone than all the birds or all the mammals in the world.

And this may give us an idea of why they're not changing very much. That degree of species diversification happened very early, and may mean that any niche which could be filled by an ant-like creature now is. Moreover, as niches change, the fast ant reproduction cycle and their huge biodiversity may mean they change rapidly to keep up. In our brief human experience, then, it may be that evolution has largely 'solved' the challenges of being an ant, so that unless the environment changes drastically, any further adaptation will be much slower, under a law of diminishing returns.

I hope this arm-wavy explanation helps. :)
janesix
Posts: 3,466
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4/5/2015 11:49:57 AM
Posted: 1 year ago
At 4/5/2015 2:21:32 AM, RuvDraba wrote:
At 4/4/2015 5:10:35 PM, janesix wrote:
How do ants stay the same for hundreds of millions of years?
Shouldn't organisms be changing more? Why do some change rapidly and often, while others stay the same for tens of millions of years or more?

Insects are one of the most diverse classes of animals in the world, Jane. There are an estimated six to ten million extant species, of which some 12,000 species alone are ants. This compares to about 10,000 extant bird species, and about 5,516 mammal species. So ignoring all the other insects, there are more ant species alone than all the birds or all the mammals in the world.

And this may give us an idea of why they're not changing very much. That degree of species diversification happened very early, and may mean that any niche which could be filled by an ant-like creature now is. Moreover, as niches change, the fast ant reproduction cycle and their huge biodiversity may mean they change rapidly to keep up. In our brief human experience, then, it may be that evolution has largely 'solved' the challenges of being an ant, so that unless the environment changes drastically, any further adaptation will be much slower, under a law of diminishing returns.

I hope this arm-wavy explanation helps. :)

Ok, that makes some sense. Thank you for responding.
tkubok
Posts: 5,044
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4/6/2015 1:57:07 AM
Posted: 1 year ago
At 4/4/2015 5:10:35 PM, janesix wrote:
How do ants stay the same for hundreds of millions of years?

Shouldn't organisms be changing more? Why do some change rapidly and often, while others stay the same for tens of millions of years or more?

The answer is a bit of a mix.

Ants dont change because they dont need to change. The environment that ants live in has provided little reason to change.

That being said, when the time comes for ants to have to change, their ability to change and adapt, survive, is partly based on chance. Even if they change, if they dont change fast enough, or if their change isnt benefitial enough, they will still die. Its why 99% of the species on this planet has gone extinct.