Thursday, April 2, 2009

The Shop is Open


You have a test over chapters 22-25 tomorrow and I will be available all day for questions. Just write your question(s) as a comment to this post.

Mr. Baker


Shauna said...

Is sympatric speciation "overnight" evolution? Is it just mutated genes from two different parental species? Can it happen in the animal world?
Does microevolution add up to macroevolution (in a sense)?
ok and the rest of my questions are non-for-the-test questions, that don't need to be urgently answered...
For domesticated animals(such as dogs) can we add breed to the end of the whole kingdom, phylum, class, order, family, genus, species?
Have we changed domesticated animals evolution ( I realize it is not a plan) by taking them out of a natural habitat? Is it still considered natural selection?

Mr. Baker said...


I am not familiar with the term "overnight" evolution but here goes. In plants it has been observed that they can produce viable offspring when the chromosome number is changed. This can result from nondisjunction in an individual or hybridization between species with different chromosome numbers. These offspring with different chromosome numbers can produce viable offspring after mating with individuals of the same altered chromosome number and not with the parental species. This can occur in one generation and it has been observed in plants. I will have to check about animals.
Can microevolution add up to macroevolution? Yes but from the evidence we have now it will probably have to involve the genes I mentioned in class. The genes that regulate development; the body plan (HOX genes), proportions, and timing. I suspect that in the coming years there will be other genes discovered that control development and body plan. The microevolution/macroevolution dichotomy is somewhat arbitrary. The kind of evolution we see in changing gene frequencies or beak length in a few generations is called microevolution. While long-run evolution which is the accumulation of many small (microevolutionary) changes which could also involve body plan and pace of development changes is considered macroevolution. It all part of the same process.
Can we breed to new classes etc? In theory we can. We regularly artificially select creating what would be in nature new species and genera. I don't know that we have tried to make new families of vertebrates? I will check. but in plants and microorganisms we have.
Have we changed the evolution of domesticated animals (and Plants)? You bet. Many of the domesticated breeds that have been in selective breeding programs for many generations would do quite poorly in the wild. But it is a kind of selection. When humans select animals/plants it is called artificial selection. It is important to note that even domestication which is a softer form of artificial selection can produce less fit organisms. For example, in salmon it has been found that wild born and raised salmon return 10X more spawning adults than salmon raised in a hatchery. Just a short period of their life (6 months) in a hatchery alters thier fitness that much. Thanks for the questions.

Mr. Baker