What Causes Species to Multiply?

[omerusta]

What is the best answer to this question.
I have a very simple answer in my mind and wonder if anyone else can share it with me.

 

[Ryan_m_b]

Because there are are many ecological nichés on Earth and evolution allows organisms to diversify to fill these nichés.

 

[mishrashubham]

What is the best answer to this question.
I have a very simple answer in my mind and wonder if anyone else can share it with me.

Diversity in the living world is a direct result of the diversity in the local environments on earth. Evolution causes organisms living in any such environment to maximize their survivability.

However it would be wrong to assume that there would be only a few species had the entire surface of the planet been identical; since different organisms can exploit their environment differently and over time, influence and modify their surroundings.

 

[Ryan_m_b]

However it would be wrong to assume that there would be only a few species had the entire surface of the planet been identical; since different organisms can exploit their environment differently and over time, influence and modify their surroundings.

Indeed, like the opposite of convergent evolution organisms can adapt to utilise the same resources in different ways.

 

[omerusta]

Diversity in the living world is a direct result of the diversity in the local environments on earth.

This is not an acceptable explanation.

Species do not evolve because of the environment.
Species evolve for the environment.

 

[bobze]

This is not an acceptable explanation.

Species do not evolve because of the environment.
Species evolve for the environment.

No.

This is something that is hard to understand about evolution and is not intuitive to most of us. Adaptation is not the goal of evolution, it is the byproduct of differential survival and reproduction.

Population's don't mean to evolve for their environment. Their environment (and by environment I mean the sum total of their biotic and abiotic interactions) is responsible for differential survival and reproduction. Populations do evolve because of their environment.

Some variation will be better in a given environment than others. How successful a certain variant is always contextual to the environment it exists in. Some new variation may not be beneficial in your current environment (your including your niche), but in a different environment it will be.

So when new environments open up or current environments are changed, we have the environment driving differential survival and reproduction--Which is what "suits" organisms to that new or changed environment.

 

[mishrashubham]

Indeed, like the opposite of convergent evolution organisms can adapt to utilise the same resources in different ways.

True

This is not an acceptable explanation.

Species do not evolve because of the environment.
Species evolve for the environment.

As Bobze said above. Evolution is not an active process in the sense that organisms don't have a conscious goal of becoming better suited to their environment. It happens passively, on its own. Even though we use words such as "Species X evolved into species Y", we do not mean to attribute the process of evolution to the the organism.

 

[Proton Soup]

As Bobze said above. Evolution is not an active process in the sense that organisms don't have a conscious goal of becoming better suited to their environment. It happens passively, on its own. Even though we use words such as "Species X evolved into species Y", we do not mean to attribute the process of evolution to the the organism.

but what about the human organism? do we not now make conscious decisions about our own evolution or is free will still just an illusion? perhaps it is just a philosophical question without an answer, but if you answer yes, there are implications about other species. traits that once may have been considered uniquely human like language or tool use no longer hold true.

 

[apeiron]

What is the best answer to this question.
I have a very simple answer in my mind and wonder if anyone else can share it with me.

Generally speaking, it is because work is wasteful and complexity is required to maximise the efficiency.

Life exists to accelerate the dissipation of energy gradients in accordance with the second law of thermodynamics. This is the work it does. But life operates most efficiently at some particular scale, and the gradients exist over all scales.

So mouths that are designed to be good for eating slices of bread are far less efficient for eatiing crumbs. Or loaves. Therefore selection would favour the filling of all possible niches, (all available scales of bread-consumption), by creatures of all scales.

There is of course a trade-off (otherwise the number of individual species would increase in almost limitless fashion). And the problem with too much specialism is that the whole ecosystem becomes less adaptable to perturbation - to some general shift in their environmental circumstances.

So if there is a lot of change in the world, then this would tilt the scales back towards fewer and more generalist species.

There are other factors. Environmental diversity would seem to be a driver of species diversity as well. But rich ecosystems are normally the result of large and reliable environments - where the variety of species themselves creates an environment of more diverse opportunities. Energy to be captured over all scales.

 

[Ryan_m_b]

This is not an acceptable explanation.

Species do not evolve because of the environment.
Species evolve for the environment.

As others have outlined this statement is incorrect so I won't go over why it is wrong again, do you see now why it is wrong? You mentioned that you had an idea, care to share it?

 

[omerusta]

Species evolve first and then adapt to environment.
Environment does not trigger speciation.

 

[Ryan_m_b]

Species evolve first and then adapt to environment.
Environment does not trigger speciation.

No you are getting confused. Organisms are formed through abiogenesis. We don't yet have a complete understanding of how this occurs but an organism will only arise if it is suited to the environment it has formed in.

Once a self-replicating with error organism has formed it will begin evolving. Mutations will occur in subsequent generations changing the biology of the organisms, some of these mutations may make the organism less able to procreate than others. Some of these mutations however could make the organism more able to procreate (e.g. by increasing survival). Over time a species will become well adapted to the environment.

If some organisms in that species are separated from the others then over time they will accumulate a different set of mutations until eventually they are different species. Speciation is caused by two groups of an organism no longer procreating, the environment can drive this by either causing a physical separation or one of the groups could adapt to utilise different aspects of the same environment.

Here is a great diagram explaining different mechanisms of speciation, each process requires adaptation to a new environment or different aspects of the same environment http://upload.wikimedia.org/wikipedia/commons/5/53/Speciation_modes.svg

Once again what is your answer? You claimed to have an idea.

 

[omerusta]

Speciation does not follow certain specific environmental cues.
There are no such cues.
It follows its own dynamics. Environmental adaptation is the final result. It is not the cause of speciation. Those that adapt survive.

Millions of different species share the same environment. Amazon rain forest is a good example.

Species do not evolve to adapt certain environment. They just evolve and adapt. Those do not adapt perish.

 

[omerusta]

Once again what is your answer? You claimed to have an idea.

Do not hurry! First things first.

 

[mishrashubham]

Speciation does not follow certain specific environmental cues.
There are no such cues.

How do you define "environmental cue"? May be it's just me with my bad English but I really don't understand what you mean by that term.

Environmental adaptation is the final result.

Not necessary. Speciation can happen due to a combination of genetic drift, gene flow and natural selection. Check Genetic Drift.

Species evolve for the environment.

Species do not evolve to adapt certain environment.

Um, aren't you contradicting yourself? Unless you mean something different by saying "evolve for". Clarify please.Here is an extremely informative post by Bobze from an old thread that you might want to read in order to get a better insight.

Think about it like this (I find this analogy always helps people). Suppose I had this color bar representing an evolutionary lineage:

Now suppose I asked you to draw a line between red and orange. Where you draw the line and where I draw the line will probably be at two different RGB values. The reason being of course, the change from the "red species" to the "orange species" is very subtle--Its not a "click and where there" kind of thing. Rather it is an extremely gradual change in RGB values where a single pixel line (a "generation") is essentially (to us visually anyway) indistinguishable from the next.

Likewise, "species" are the same way. The variation vertically in anyone generation, is typically less than what is found within the population at large. Therefore, from parent to offspring (generation to generation) the distinction between "species" doesn't actually exist.

It only exists because the fossil record is incomplete (for example, we may have many "in between" generations missing between red and orange) and we are observing it in hindsight. Because of the incompleteness artefactual "divisions" can exist in a lineage--Which we call "species".

Consider another thought experiment put forth by Dick Dawkins. Which addresses the problems with the "biological species" concept and evolutionary lineage historicity.

Suppose you and I have a time machine and were off to collect historic ancestors in a manner rivaling the Victorian rape of the natural world. The ol' snatch and grab.

Suppose we dial our flux capacitor back to 10,000 BC and hop back through time.

[PLAIN]http://t1.gstatic.com/images?q=tbn:ANd9GcQV9wpCBWK5jCOo40cAhCAx22KahbsY6xfZA-TFxbD3zD3Rc1vYyQ

Abducting a person then bring them back to our future. In our sick experiment, we convince a modern individual to breed to this person from an ancestral population and see what happens.

Probably, we get offspring. So according to the biological species concept (we can interbreed--Simplified) we are of the same "species" as the individual from 10,000 BC.

No suppose we repeat our foray into history many times, hopping back in 10,000 year intervals. Eventually we run into an individual, well call individual X that cannot interbreed with us. So have we found an objective measure of our "species" its "ultimate origin"?

Consider the individual we abducted before X, we'll call Y. Individual Y, who we can interbreed with and is therefore "of our species" could very, very likely interbreed with individual X. In other words, individual Y's "X" is not the same as our "X", though both us and Y and still interbreed.

How then, can we have found a finite boundary to our species, when members we consider our "species" can interbreed with those "not of our species", while we cannot?

Species, much to the discomfort of even many professional biologists, aren't real tangible things---Lineages and populations are.

Do not hurry! First things first.

What is the point that you are trying to make by not telling your idea?

 

[Evo]

What is the point that you are trying to make by not telling your idea?

He was pointing out that he's a troll.

I'm leaving the thread up because there are some great explanations that will be helpful to *real* people.

 

[Euro Murzi]

The evolution change is not adaptative, but innovative accompany of adaptation.

 

[Ryan_m_b]

The evolution change is not adaptative, but innovative accompany of adaptation.

Welcome to PF Euro Murzi. I'm afraid I can't make sense of what you are saying here.

 

[Euro Murzi]

Innovative means "new things"! If adapt stay, if not, perish.

 

[Ryan_m_b]

Innovative means "new things"! If adapt stay, if not, perish.

True though time scale matters. Some species have remained unchanged for millions of years, I remember an evolution lecture years ago where the prof. was telling us about a tree whose 15 million year old fossil had been found to be nearly identical to the modern day variety.

 

[Euro Murzi]

That’s true!

Evolution did not change continuously, but by sudden and dramatically transitions.

Unchanging periods of thousands of years is the normal rule!

 

[Ryan_m_b]

Well that is true in the case of punctuated equilibrium but this mainly applies to speciation rather than evolution as a whole.

Remember there are many processes within evolution besides the formation of new species.