Do we know when # of species peaked?

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MarcoPolo

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In what I’ve read lately, I understand macroevolutionist theory entails a singular common “ancestor” for all life forms, plant & animal. I’m also aware of claims of a dramatic decline in the number of species in recent years.

So apparently we are moving back toward one species?

And when was the high point? When did we have the maximum number of species?

Or is some of the above fallacious?
 
MarcoPolo said:
In what I’ve read lately, I understand macroevolutionist theory entails a singular common “ancestor” for all life forms, plant & animal.
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Correct. Though it could possibly have been a small group of common ancestors.
I’m also aware of claims of a dramatic decline in the number of species in recent years.
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Impossiible to absolutely confirm such claims, but they are probably correct.
So apparently we are moving back toward one species?
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Doubtful. The number of species can increase as well as decrease.
And when was the high point? When did we have the maximum number of species?
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Pass. We do not even have an accurate count of how many species there are alive currently. It is even more difficult to count the number alive in the past, as many species do not fossilise at all well.
Or is some of the above fallacious?
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No, you were pretty accurate.

rossum
 
MarcoPolo said:
In what I’ve read lately, I understand macroevolutionist theory entails a singular common “ancestor” for all life forms, plant & animal. I’m also aware of claims of a dramatic decline in the number of species in recent years.

So apparently we are moving back toward one species?

And when was the high point? When did we have the maximum number of species?

Or is some of the above fallacious?
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The high point would likely have been at the beginning of creation. As time goes on, more and more species get lost through extinction. Thereby diversity gets lost.
 
There are periods of mass extinctions, and periods following of great speciation (punctuated equilibrium). Saying when number of species peak then is entirely relative.
 
So according to macroevolutionists, the number of species is always rising and falling, and we are currently in a fall?

Correct?
 
An honest biologist would have to concede that nothing remotely like hard numbers on total number of species exists. All we REALLY know is that there is an alarming trend of reduction in diversity of species found in test plots in varied locations all over the world. Call it the McDonalds/Walmart effect. Diversity is giving way to uniformity in the biological world and in the retail world at the same time.

Coincidence?? Spooky! … 😉 :rolleyes:

Must all be Sam Walton and Ray Croc’s fault.
 
manualman said:
All we REALLY know is that there is an alarming trend of reduction in diversity of species found in test plots in varied locations all over the world.
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What the sample shows would be important I would think. If macroevolution is seen to be survival of the fittest, with species improving over time, then there is the question of why the direction would change as a whole, or have ever stretched to more than a couple species in each climate/environment in the first place?

However, if it is just random, then why the change in direction in number of species?
 
MarcoPolo said:
What the sample shows would be important I would think. If macroevolution is seen to be survival of the fittest,
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To be clear, the distinction between macro/micro evolution is entirely artificial. Its simply evolution.
MarcoPolo said:
with species improving over time, then there is the question of why the direction would change as a whole, or have ever stretched to more than a couple species in each climate/environment in the first place?

However, if it is just random, then why the change in direction in number of species?
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Easy, the environment rapidly changes which is difficult for many species to adapt.

Humans destroy natural habitat, hunting, elimination of certain predetors, transplanting species etc etc.
 
MarcoPolo said:
What the sample shows would be important I would think. If macroevolution is seen to be survival of the fittest, with species improving over time, then there is the question of why the direction would change as a whole, or have ever stretched to more than a couple species in each climate/environment in the first place?

However, if it is just random, then why the change in direction in number of species?
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Evolution doesn’t really imply “improvement”, in an absolute sense, only an increasingly competitive accomodation to a particular environment. That might not be an improvement, in terms of long-term survival, since particular environments don’t last forever in a particular place.

We’re losing these particular environments at a heightened pace, so the most specifically-adapted species are at greatest risk of extinction, because their particular advantages are being taken away, while the trade-off disadvantages remain or increase.

Evolution is a game that can have a changing playing field. The specialists thrive when things stay the same, but suffer when change happens.
Isambard said:
To be clear, the distinction between macro/micro evolution is entirely artificial. Its simply evolution…
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I thought that macroevolution was when species with incompatible genomes arose, as opposed to species which differed only in physical or behavioral characteristics. (That is, not won’t interbreed or don’t have a chance to interbreed, but CANNOT interbreed.)

The last I checked, there isn’t a known mechanism by which a single mutation in a single individual could give rise to a new species that differs from its ancestors in the number of chromosomes it has. I’ve always wondered how that could happen…I think some kind of a “super virus” that changes the entire DNA of a huge breeding population, maybe wiping out a huge fraction of them, but leaving behind a quorum in the new species for breeding.
 
Isambard said:
Humans destroy natural habitat, hunting, elimination of certain predetors, transplanting species etc etc.
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According to earlier posts, the fluxuation in number of species rises and falls, even prior to homo sapiens.
 
EasterJoy said:
Evolution doesn’t really imply “improvement”, in an absolute sense, only an increasingly competitive accomodation to a particular environment. That might not be an improvement, in terms of long-term survival, since particular environments don’t last forever in a particular place.

We’re losing these particular environments at a heightened pace, so the most specifically-adapted species are at greatest risk of extinction
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Isn’t it suicidal for a species to become specifically-adapted like that? If evolution is geared toward perpetuation of a lifeform, then should we not see a movement away from highly specialized species? If I am not mistaken, there are microbes that can exist in the hottest volcanic environments or the coldest reaches of the earth.
 
Isn’t it suicidal for a species to become specifically-adapted like that? If evolution is geared toward perpetuation of a lifeform, then should we not see a movement away from highly specialized species?
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Depends on the situation. There are rather involved mathematical models in population genetics that describe the fitness of specialists vs. generalists in different circumstances.
If I am not mistaken, there are microbes that can exist in the hottest volcanic environments or the coldest reaches of the earth.
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Not surprisingly, the evidence indicates that these “extremophils” are among the oldest organisms on Earth.
 
The_Barbarian said:
Not surprisingly, the evidence indicates that these “extremophils” are among the oldest organisms on Earth.
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I would think if life-forms tend toward perpetuation, then these extremophils should be the direction toward which all species are evolving.
 
I would think if life-forms tend toward perpetuation, then these extremophils should be the direction toward which all species are evolving.
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I don’t see why. After all, most living things on Earth are not extremophils; those can live only in certain hot, cold, or anoxic environments. Pretty limiting. The rest of the biosphere is open to other organisms.
 
The_Barbarian said:
I don’t see why. After all, most living things on Earth are not extremophils; those can live only in certain hot, cold, or anoxic environments. Pretty limiting. The rest of the biosphere is open to other organisms.
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You mean they can’t survive in a mild environment, like, say, Nebraska?
 
MarcoPolo said:
Well, if it’s random, then we’re back to post #7, and that lends confusion to the “trends” of growing # of species or shrinking # of species.
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It isnt random either. The environment is always changing so what’s beneficial today, is a disadvantage tomorrow.
 
Isambard said:
It isnt random either. The environment is always changing so what’s beneficial today, is a disadvantage tomorrow.
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Ok, but do you see what I am saying then. If evolution is for “beneficial” purposes, then it is goal oriented toward improving.
 
MarcoPolo said:
Ok, but do you see what I am saying then. If evolution is for “beneficial” purposes, then it is goal oriented toward improving.
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Goal-orientation implies a certain design or cognition. Evolution occurs as a result of the environment acting on a species which just so happens to sometimes favour beneficial traits. You can also get favouring of of non-beneficial triats through sexual selection or non-natural selection (ie. us).
 
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