Natural Selection Question

[saheh]

Okay so I have this question and I'm a bit stuck on how to answer it, and it's probs an obvious answer:

Allele frequencies in a population will change from generation to generation.  This is referred to as Microevolution.  What are the processes that cause this?

can anyone help??
i googled it and it came up with factors such as mutations, genetic drift, migration etcetc

[Biceps]

Allele frequencies are generally stable. However, you can get disturbances that change this stability and they happen at random.
If you remember the hardy-weinberg principles you would know that there are conditions for this stability to remain constant. if not met the population's allele frequencies change as well.
-Mutations result in new alleles being passed on to the new generations.
-Genetic drift causes changes based on pure probability because a group of individuals are no longer present in the original population. This causes a large change in the allele frequency of the population.
-Migration causes the alleles within the population to go to other populations and alleles from other populations to come in so the allele frequencies are also affected.

[slothpomba]

Finally a question i can answer!

Thats a ridiculous question. A lot of people don't make a disctinction between macroevolution or microevolution. Personally, i believe the distinction between something called macroevolution and something called microevolution is pretty much made up.

The above answer, with regards to hardy-weinberg, is excellent.

You have to remember, mutations are always occuring. In sexually reproducing species we have genetic recombination (eg. "crossing over of the chromosomes"). Thats one factor.

Remember, Mendellian inheritance is probabilistic. It's a roll of the dice. You might have a 25% chance of smooth skin and a 75% chance of rough skin. Look at this like rolling a dice a few times in a row, we'll call this a "set".

On your first set of rolls, you roll the dice 4 times and get 2, 3, 6 and 5.

On your second set, 6, 4, 1 and 5

On your third set, 5, 4, 3 and 2.

(Courtesy of http://www.random.org/dice/?num=4 ).

Even if your parents have a 25% chance of producing offspring with blue eyes, its not automatic that they will.

So, natural random variations like this as well.

Take what i said with the above posters advice as well and you should be set.

It wouldn't hurt to thank us next time either, we do this out of the goodness of our hearts and we're not magical answer machines.