Week+20+Madelaine+(Period+1)

This is not quite as fun as Trevors, but I thought it was interesting to look at the evolution of plants vs. humans. Read the articule and post one comment on something new you learned from it. [].

This is ido, in case no body know how to post **got to edit as the top right of the page and you shuld be able to type in this space below**. I found out that species cannot evolve back to their original traits no matter whether it is beneficial to them or not

My question is, how can scientists prove this theory? I mean if the theory states that once characteristics are lost thy will never return, then how do scientists know what traits have been lost? There is also the scenario with the peppered moths which, due to environmental change went from black to white and back to black. Nadia

I learned that some evolutionary traits will never die out (be reversed) because they are so useful. I had always assumed that if the environment changes drastically enough any trait could be lost or gained. I thought the last paragraph of the article was the most interesting:

“An intriguing aspect of this study is that the mechanism for ensuring cross-fertilization is very old, often lost, and never regained,” Kohn said. “That it is still common despite frequent and irreversible loss implies that this trait confers an advantage to species that possess it, perhaps in terms of reduced rates of extinction.”

I may be interpreting this wrong, but it seems Kohn is saying although cross-fertilization is a useful trait, it may one day die out and never come back again. --Evan

The ideas that environmental changes are constantly occuring (according to Hutton's theory of gradualism) and organisms can't return to their original state are reasonable in that it explains how species have developed the thousands of genotypes and phenotypes throughout generations. However, if they can develop new traits, I don't quite see why they can't develop their previous traits. As long as those traits are beneficial, it would make sense if organisms were able to develop any traits, whether they're new or the original. Sara P.

I learned that some traits are irreversable. This is helpful to some organisms because it keeps them from being extinct. Christie

I dont understand how an organism can lose "eyes, wings, and other complex traits." It seems to make sense that important characteristics such as sight would be the ones that are the ones that would not be lost. I also can not imagine a situation in which it would be beneficial to lose one's sight. Another comment that I found interesting is "Apparently, plants that have sex exclusively with other plants and not themselves, enjoy a greater evolutionary advantage,” Igic said. “Exactly why is unclear,” I do not understand why this is unclear, as it is known that sexual reproduction promotes more genetic variation than asexual reproduction. Habab

"once lost, the traits never revert to their original state". I found that very interesting because I thought that could cause problems for future evolving species. Harper

Donte Turner: I thought this article was very interesting. I didn't know that some traits are irreversible due to evolution. I don't understand the controversy with the irriversible traits though. It said that earlier studies have observed the "reappearance" of complex traits that were lost to our ancestors. What does that have to do with irreversible traits???

No worries, I found this very interesting still. It never occurred to me that evolutionary changes could be irreversible, or even repeatable. And that evolution could be separated into unidirectional or polydirectional. And also, that plants were capable of rejecting pollen they don't want to use. They should conduct a study on any irreversible changes in human evolution. --Patricia