I have a question about the evolutionary process?

Question

My friend, who is a knower of such things, told me that the fossil record shows new animals, but never shows the little steps between the new animal and the one it came from. He also said that we don't know the process that causes evolution because the Modern theory has ruled out natural selection as a way of getting new species, and genetic mutation has been ruled out because of various mathematical and fossil record problems.

He was trying to tell me about creatures getting stuck in limiting breeding populations as a part of the process and said there are some other new theories. Can anyone explain to me better the limited breeding population theory and some of the pother new theories?

Answer 1

> My friend, who is a knower of such things
Your friend appears to be biased.

> never shows the little steps between the new animal and the one it came from
Hm. Interesting. Any natural history museum with an evolution display will have an illustration of prehistoric horses. It's true that we can't point to which ones are direct ancestors of present-day horses and which are cousins... but there sure are a lot of little steps in there.
You also have a range of canines from gray wolves to Dachshunds. You can see living examples of little steps there.

> He also said that we don't know the process that causes evolution
Mutation gives new alleles. Chromosomal events also affect the genetic course of a species. Organisms are sorted out for reproductive success through isolation/genetic drift and selection.

> limiting breeding populations
That's the isolation/genetic drift component for you. On islands, you'll find species that are related to animals found on the mainland. Speciation has occurred due to genetic drift and to different selection factors present in the new limited environment.

Answer 2

Your friend is quite wrong ... on a number of things.

First, the fossil record often does not show all the intermediate steps, but it often does. It depends upon whether the organism lived in an environment that is conducive to fossilization. Even the term "new animals" is misleading ... it's not like one animal slowly becomes a "new animal" (and therefore requires intermediate steps). An animal *changes* (evolves), that's it. If two sub-populations of the same animal get separated, then they will each change in different directions and eventually become two animals.

Second, natural selection is still the prevailing theory that explains evolution (slow change) of species, and the creation of new species. Again, natural selection is the engine of *change* ... constant, relentless, change. What causes new species is when two sub-populations of the same species get temporarily isolated genetically ... and then undergo changes (driven by natural selection) that makes them different. All it takes is enough TIME for these differences to make them genetically incompatible, and then their genetic isolation is forever *permanent*. Even if they do encounter each other, they are no longer able to interbreed. They have become the definition of two separate species. Two separated species can never regain the ability to interbreed.

Third, I don't know what he means by "genetic mutation has been ruled out because of various mathematical and fossil record problems." I have never, ever, heard or read any scientist say that. People who say that generally have a wrong understanding of mutation ... that somehow you go from, say, no insulin molecule, to a mutation that creates an insulin molecule from nothing. Such a mutation would be mathematically impossible ... but that's not how it works.

As far as limited breeding populations, that is true. (That's exactly what I was saying above.) Other names for this are the "founder effect" (when it happens to an isolated sub-population) and "population bottleneck" (when it happens to an entire species due to something like a drought ... which can lead to isolated populations, and thus the founder effect). When a sub-population gets separated from the rest of its species, the small number of individuals means that genetic changes can propagate *very* fast through the population. But this is not different from natural selection. It IS natural selection ... only on a smaller population.

See the two wiki pages I list under 'source'. They give better explanations that I can here, because they can use illustrations and better cross-linking.

Answer 3

Your friend who told you that natural selection and chance mutations have been ruled out is 100% incorrect. Natural selection basically encompasses all the ways that speciation can occur. In terms of limited breeding, it basically implies that a specific community within a population will only breed amongst each other, for whatever reason (geography, temperature, etc.). Eventually, this group will develop hereditary differences from the father population and be unable to interbreed with them. This creates a new species. However, this is not as common as other evolutionary events, such as mutations that lead to natural selection.

Answer 4

There are numerous transitional fossil discoveries.
Natural selection has been demonstrated in the field and the laboratory.
Genetic mutations and duplications are the major mechanisms creating the diversity for natural selection.
Isolated populations are not new. Darwin's finches are a classic example of new species arising from a limited population in geographic isolation.
Most of the other new theories are about the mechanisms, not the big picture.

Answer 5

Well, for starters your friend is clearly NOT a knower of such things. Sounds more like someone who has just enough information to be able to confuse the issue. Typical strategy for intelligent design theorists or other such people with a religious agenda.
Pick up The Ancestors' Tale by Richard Dawkins for a good history. There's far more to evolutionary theory and what the record shows or doesn't show for anyone to be able to explain it in this forum.