I see what you are saying here.
And so I wonder if the tendency you are describing is “hooked” to the use of the phrase “responding to selection” versus “responding to drift”.
It is my impression that the tendency I was describing was a Small Population’s increased sensitivity to DRIFT.
Your observation about size correlating to increased sensitivity to NATURAL SELECTION is an excellent nuance!
Sorry, what tendency? If you’re talking about adaptation, that’s more often a result of selection than drift. And I perhaps should have said that selection is a weaker force in small populations rather than that drift is stronger. The same number of neutral mutations are fixed per generation in a large population as in a small one. Then again, fewer deleterious mutations are fixed per generation in a large population than in a small one, and the ones that are fixed are less deleterious. But I don’t think this helps adaptation in the small population.
Any fruit fly experiment in a lab setting is not going to be able to model real populations of fruit flies. They simply can’t raise enough fruit flies to do it properly. Things like severe bottlenecks every 10 generations are going to have serious impacts on genetic variation and fitness.
Evolution works like a feedback loop which causes populations to track environmental changes. When the environment is stable or slowly changing over long periods you get slow gradual morphologic change. When the environment changes relatively rapidly you get relatively rapid morphological change to keep the species near its local fitness maximum. If the environment changes too rapidly or too drastically (i.e the Chicxulub impactor) the tracking loop can’t keep up and the species goes extinct.
In the fossil record we see both; examples of stasis/gradual change and examples of rapid change. There isn’t a “one size fits all” pattern. One of the major concerns now with AGW / climate change is we are changing the environment way too fast for many species to adapt. We’re entering a global sixth mass extinction period because of it.
Species go extinct during all the above periods. Which means that there is no guarantee of any species adapting to any change whether the environment changes slowly or fast.
I think what you are dishing is a just so story.
Perhaps @John_Harshman can comment.
Didn’t you just post that as a population gets larger, it becomes less sensitive to DRIFT and more sensitive to natural selection?
I thought this was a subtle but important distinction. So are you now disagreeing with yourself because I agreed with your earlier self?
I was talking about the general overall patterns seen in the fossil record. “Environment” doesn’t just mean the local weather conditions. It’s everything which affects the population’s survival - their food supply, their predator/prey relationship with other species, a new pathogen sweeping through the population (i.e. Tasmanian Devil and their face cancer)
True, there is no guarantee. But it’s more likely that a population will be able to adapt to slow change than to rapid change. Is this at all controversial? And it’s impossible to adapt to a radical change that takes only a few minutes, like that impact. I’m not sure whatyou’re complaining about.
Sort of. But I didn’t know that’s what you meant by “this tendency”. Also, “sensitive” seems like the wrong word. It’s often hard to tell what you’re trying to say. And no, I am not reflexively disagreeing with everything you say, and I’m never disagreeing with myself.
The thing with the fossil record is that it’s not complete. A volcano might preserve more fossils in the ash than a less violent change. However it’s very difficult to actually prove that sudden changes witness more extinction events than gradual ones as a rule.
Besides, most animals in the fossil record are extinct in spite of whether the change was gradual or fast.
Now you are basically saying that changes that lead to extinction cause extinction.
For example a localised drought could cause a species to go extinct… it could also cause it to migrate and thrive.
Edit: same thing with pathogens… could cause extinction or adaption of resistance to the disease.
I think we can all agree that it’s often hard for you to tell what I’m saying.
I am inclined to lyrical narrative, assuming that the connections are obvious.
But that’s why I’ve been married and divorced three times. What is obvious to me is not obvious to everyone.
But honestly … if you don’t understand what I’m writing … ask @swamidass… he almost ALWAYS understands what I’m trying to say.
ADDED NOTE: “Sensitive” is being used like “sensitivity test” or “reactivity test”. It is not a sloppy anthropomorphic reference to having “feelings”.
If you have a word that you think fits better than “sensitive” or “sensitivity” … pass it on here… I would love to use it.
It’s complete enough we can see the general pattern in most lineages. We don’t need a fossil from every generation to see the overall pattern.
(facepalm) which is why I said there is no "one size fits all’ pattern. The specific evolutionary path followed by each lineage is of course going to somewhat different because all species aren’t identical. Do you think that’s some big revelation?
Perhaps some of that responsibility lies with you, and you should put more effort into how you express yourself. Just consider the possibility. The effort should probably not go into typography; as I’ve said, shouting doesn’t increase clarity.
What is observed are historical patterns where some catastrophic events lead to mass extinctions.
Such patterns need not be a rule.
For example, if the meteor that wiped out the dinosaurs fell much earlier before the “evolution” of multicellular organisms, it wouldn’t have cause many extinctions … if any.
Not at all… expected you to know it before spinning stories.
He’s being the typical ID-Creationist. Flinging any mud he can at his evolutionary theory strawman and seeing if any sticks.
I can see you’re unacquainted with the mass extinction of forams at the K/T boundary. If you’re just saying that mass extinctions are contingent on their being species to become extinct, then sure, that’s true. But it hardly seems like a point worth mentioning.
It’s really unclear what you’re trying to say.
I am just saying that the rate at which organisms change is random and not dependent on how fast or slow the environment changes.
What justification do you have for that claim?
Mutations are random… So a change in environment should not cause a beneficial mutation to pop up…
Evolution is supposed to be driven more by neutral mutations/drift than natural selection… so am assuming selection isn’t powerful enough to change the random nature of the change.
Rapid changes in environment will put strong selection pressures on beneficial mutations and increase the rate of change.