Three examples of macroevolution

[Miles]

In answer to a previous question about macroevolution (evolution at the species level or higher), I posted the following examples in another thread; however, on thinking about it I decided they deserve a better exposure---macroevolution is hotly contested by creationists.

• 1. "While studying the genetics of the evening primrose, Oenothera lamarckiana, de Vries (1905) found an unusual variant among his plants. Oenothera lamarckiana has a chromosome number of 2N = 14. The variant had a chromosome number of 2N = 28. He found that he was unable to breed this variant with Oenothera lamarckiana. He named this new species Oenothera gigas."
  
  
  2. "Digby (1912) crossed the primrose species Primula verticillata and Primula floribunda to produce a sterile hybrid. Polyploidization occurred in a few of these plants to produce fertile offspring. The new species was named Primula kewensis. Newton and Pellew (1929) note that spontaneous hybrids of Primula verticillata and Primula floribunda set tetraploid seed on at least three occasions. These happened in 1905, 1923 and 1926."
  
  3. "The Russian cytologist Karpchenko (1927, 1928) crossed the radish, Raphanus sativus, with the cabbage, Brassica oleracea. Despite the fact that the plants were in different genera, he got a sterile hybrid. Some unreduced gametes were formed in the hybrids. This allowed for the production of seed. Plants grown from the seeds were interfertile with each other. They were not interfertile with either parental species. Unfortunately the new plant (genus Raphanobrassica) had the foliage of a radish and the root of a cabbage."
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So, can we finally close the book on the creationist's contention that macroevolution is but a fantasy of science?

[Cathar1950]

Unfortunately the new plant (genus Raphanobrassica) had the foliage of a radish and the root of a cabbage."

That is to bad. Now if they could get a root of a radish and the foliage of a cabbage we could have a pretty good harvest.
I hope they don't stop trying.

[handofnergal]

Technically Speciation is defined as a macroevolutionary process, and since there are thousands of cases of observed and in some cases induced speciation, they should all count as well.

When I point that out to creationists they just say " nuh uh" and I'm like "yeah huh" and they go "no" and then I just ignore them because they have brain damage.

[Goat]

Technically Speciation is defined as a macroevolutionary process, and since there are thousands of cases of observed and in some cases induced speciation, they should all count as well.

When I point that out to creationists they just say " nuh uh" and I'm like "yeah huh" and they go "no" and then I just ignore them because they have brain damage.

That is why I tried to get certain evolution deniers what they mean by 'macro-evolution'. They avoided the challenge, and actually showed how little they know about the subject.

[Miles]

Technically Speciation is defined as a macroevolutionary process, and since there are thousands of cases of observed and in some cases induced speciation, they should all count as well.

When I point that out to creationists they just say " nuh uh" and I'm like "yeah huh" and they go "no" and then I just ignore them because they have brain damage.

That is why I tried to get certain evolution deniers what they mean by 'macro-evolution'. They avoided the challenge, and actually showed how little they know about the subject.

Which also says a lot about the basis of their personal faith: "I'm ready to believe or disbelieve whatever is necessary to keep me happy and feeling secure."

Such deliberate self deception is sad, really.

[otseng]

Let me get this straight. You bring up evidence of plants that cannot breed and this proves macroevolution?

[handofnergal]

I fail to see how it disproves macro-evolution, he made a new breed in the experiment, and as I have already stated, changes outside of a species are macro by definition itself.

[Bio-logical]

To add to the examples in the animal kingdom local to me here is Wisconsin we have two species of tree frogs that are indistinguishable from each other without either a karyotype or by hearing the two species calling in the same pond at the same time (one has a faster trill than the other).

The Cope's Gray Tree frog (Hyla crysoscilis) and Eastern Gray tree frog (Hyla versicolor) are another example of a polyploid viable offspring that causes immediate speciation. Cope's gray tree frog is diploid, Eastern is tetraploid. This means that the entire genome of cope's was duplicated in an offspring due to improper nuclear fission and the new offspring lived, was able to reproduce with itself (and its siblings, frogs are explosive breeders and there would be thousands) but not its parents. An instant new species, separated by a breeding barrier. From this point forward, micro evolution will effect their species differently and the two will become more distinct from each other.

The problem with these examples is that they are poor examples of how speciation typically occurs. Polyploidy rarely results in viable offspring, especially in animals. it happens alot in bacteria but the more complex the organism, the less likely it will work. What polyploidy represents is what the focus should be.

It represents separation. Separation is the most common driving force in speciation. Be it by distance, physical barriers (i.e. mountains, cliffs, rivers) or by mating barriers (polyploidy, mutation of the sex organs, fertility cycles, mating methods...) one peculiar example is is salamanders that mate by dropping a sperm glob and then moving forward one body length so that the female picks it up behind them. With a mutation that effected body length, only those with the new mutation could breed together, otherwise parts didn't match up when one body length was moved (I can't remember species name, it was in one of my colege texts).

The cause of speciation is almost always separation. Parapatric, sympatric, allopartric... although they are quite different, they all rely on one simple thing, inability to interbreed, be it due to distance or anything else. When interbreeding does not happen for a sufficient amount of time, micro-evolution causes macro. Time is the ingredient that gets removed when polyploidy occurs, which makes it a nice case study, but otherwise only an example of one type of sympatric speciation.

[JoeyKnothead]

While I accept the examples as speciation, as well as the general notions of the ToE, I still don't think these will be considered sufficient examples.

Until we can actually observe all the steps of a fish turning into a moose or some such, there will be enough doubt for those who reject macroevolution claims. This doesn't mean they're gonna be dishonest in their rejection.

I would still contend there is a preponderance of evidence that allows us to reach a reasoned conclusion that macroevolution has and will continue to occur.

(Edit for tags)

[Miles]

Let me get this straight. You bring up evidence of plants that cannot breed and this proves macroevolution?

NO.

• "In some cases, closely related species *can* hybridize, and if their chromosome sets differ in number, each chromosome in the hybrid is univalent (i.e., it has no homologous "mate"), and meiosis cannot proceed normally (no synapsis; no crossing over; random segregation of c'somes into forming gametes; inviable gametes)
  
  Viable hybrids have been produced in the laboratory, and it's possible that they could occur in similar fashion in natural situations. Here's an example of an artificially produced "new species."
  
  Brassica oleracea (cabbage) x Raphanus sativa (radish)
  
  * Both species 2n = 18; n = 9
  
  * Breeding between the two species produces an F1 generation in which 2n = 18 (but actually is 9 + 9, since the chromosomes are not homologous).
  
  * But if somatic doubling (i.e. nondisjunction of an entire set!) occurs in a MERISTEMATIC cell that later develops into a reproductive part of a flower...
  
  Result: 2n = 36. In effect, each parental chromosome set has "created" its own homologous set and migrated with it into a new cell.
  
  * At this point, normal meiosis, complete with synapsis and crossing over can occur. Because these plants are usually self-fertile, they can produce offspring, even if there is only one such individual. This "new genus/species" was named Raphanobrassica. <-- Click
  
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