When I watch nature shows, sometimes the narrator says that certain animals such as cockroaches and sharks have stayed relatively the same for thousands for years.
Isn't natural selection and evolution supposed to be a fierce competition with an animal's prey and predators? Is it understood how they gained such a large advantage (that they could stay that way for thousands of years) if each few generation is supposed to be the tiniest of changes?
Note, I am not one of those crazy religious fundies. I would like to know what is the most supported explanation
2007-12-27 17:40:24 · 6 answers · asked by Moo 5 in Science & Mathematics ➔ Zoology
Wouldn't the predators of the cockroach become more effective over time?
2007-12-27 17:54:32 · update #1
"Stabilizing selection" or "canalizing selection" is natural selection that keeps an organism as it is. Selects AGAINST change. It's still an evolutionary mechanism, though.
2007-12-27 19:14:57 · answer #1 · answered by floreana_baroness 3 · 0⤊ 0⤋
Environmental change is the force behind natural selection. Changes in environment may allow some mutations to provide an advantage while others do not. Organisms do not mutate at will, it is random. Evidently in the genome of such organisms as sharks, mutations did not necessarily provide any advantage and were not "selected". This reduces change.
2007-12-28 01:49:18 · answer #2 · answered by ScSpec 7 · 0⤊ 0⤋
Everyone is right about the lack of need to change.
About predators, in the case of sharks, the only predators that feed on sharks are humans and other sharks. Technically, you can say that humans out-evolved sharks to be able to feed on them.
In the case of cockroaches, they simply maintained success because they breed quickly, are not very tasteful (they really don't have many predators), and know to scatter at the first sign of trouble.
2007-12-28 10:24:14 · answer #3 · answered by Todd 7 · 0⤊ 0⤋
You pretty much hit the mark there with the large advantage. The environment hasn't changed enough to effect a cockroaches or a sharks ability to survive. Why change something that's not broken?
2007-12-28 01:44:34 · answer #4 · answered by Jeremy D 3 · 2⤊ 0⤋
Because they don't need to change. Some changes occur of course, but the ones who mutated or had something different were probably at a disadvantage, which is why those genes didn't pass on.
2007-12-28 10:18:22 · answer #5 · answered by Akatsuki 7 · 0⤊ 0⤋
this is a good question. i think natural selection makes the changes needed for the environment. our bodies evolve over time, but some animals bodies don't need to evolve, because they can live in their environment without having to change.
2007-12-28 22:53:54 · answer #6 · answered by crystal spring 4 · 1⤊ 0⤋