2007-12-31 12:53:22 · 4 answers · asked by Buttrefly-Beauty 2 in Science & Mathematics ➔ Biology
The basis of natural selection is that there are differences among all members of a species. Some of those differences will be more useful in difficult, challenging environments. Those who have the desirable trait succeed and reproduce thus passing that trait on. In future generations, more members of the population have the desirable trait. That's evolution in a paagraph.
2007-12-31 13:01:31 · answer #1 · answered by bioguy 4 · 2⤊ 0⤋
Here is something I just read: In Nepal at very high elevations, women with higher levels of oxygen in their blood have more than twice as many babies as women with normal levels of oxygen in their blood.
This is an excellent example of natural selection. The oxygen poor environment is favoring those with more oxygen in their blood. As time goes by, a higher and higher percentage of the population will have these higher oxygen levels. If these people remained isolated for enough generations, eventually everyone will have the higher oxygen levels. If they remained isolated for 100,000 years, there is a good chance there would be a mutation that would make it impossible for them to interbreed with other humans or if they did, the offspring could be sterile.
2007-12-31 13:32:26 · answer #2 · answered by Joan H 6 · 2⤊ 0⤋
The theory is that it removes some genetic diversity, by allowing some organisms to either die or not reproduce successfully. This reduction in genetic diversity is the point at which we are most interested because that is the point at which the species changes significantly.
Over time, the theory goes, mutations increase the genetic diversity of the gene pool, then, there is a period of 'natural selection' where certain alleles (variations of the gene) are 'killed off'.
This theory explains how species can give rise to new species. It is clearly not a purposeful process and beneficial alleles are entirely accidental, when they first arise through mutation. Of course these accidental alleles may prove useful and this is why the theory is commonly misunderstood to be a purposeful process, as the genes are useful.
2007-12-31 13:18:11 · answer #3 · answered by Noz 3 · 1⤊ 0⤋
In the case of butterflies it is not so clear.... what series of small changes each propelled by an advantage would make a crawly caterpillar wrap itself in a cocoon and morph into a flying creature.
It does make a rather beuatiful picture of life in heaven after earth tho.
2007-12-31 13:03:57 · answer #4 · answered by whirlingmerc 6 · 0⤊ 4⤋