Evolution+of+Populations

__**Evolution of Populations**__
By Vicky Nguyen


 * Chapter 23.

Related Activities**
 * Lab 8
 * Chapter 23 outline
 * Island Biography and Evolution (Phylogenetic Puzzle)


 * Related Links**
 * Lab 8: [|Population Genetics and Evolution]
 * [|Hardy - Weinberg Problems]


 * Vocabulary**
 * Page 429
 * population genetics
 * population
 * species
 * gene pool
 * Page 430
 * genetic structure
 * Hardy - Weinberg theorem
 * Hardy - Weinberg equilibrium
 * Page 431
 * Hardy - Weinberg equation
 * Page 432
 * microevolution
 * genetic drift
 * Page 433
 * bottleneck effect
 * Page 434
 * founder effect
 * gene flow
 * mutation
 * inbreeding
 * Page 435
 * assortive mating
 * natural selection
 * Page 436
 * polymorphism
 * geographical variation
 * Page 438
 * balanced polymorphism
 * heterozygote advantage
 * Page 440
 * Darwinian fitness
 * relative fitness
 * Page 441
 * diversifying selection
 * sexual dimorphism
 * sexual selection

The __Hardy - Weinberg Theorem__, named for two scientists, describes the genetic structure of a nonevolving population. It says on page 430, that the frequencies of alleles and genotypes in a population remain the same generation after generation. In this theorem, the population's genetic structure is in a state of equilibrium - __Hardy - Weinberg equilibrium__, and their equation helps us calculate the frequencies of alleles in a gene pool if there is the right given information.
 * Important Content**

Hardy - Weinberg Equation: p + q = 1 p² + 2pq + q² = 1

If a population is evolving, there will be changes in allele and genotype frequencies. Therefore, the changes describe microevolution. __Microevolution__ is caused by five different factors (listed in the ch. 23 outline given and p. 432). The first factor that causes microevolution is __genetic drift__ which is where there are changes in the gene pool of a small population due to chance. Another factor is the isolation that occurs from other populations. This means that natural disasters could occur which results in the reduction of a population, which changes and transfers alleles. __Mutations__ is another reason as to why microevolution occurs, random mating also contributes to microevolution where individuals choose their mates and no __natural selection__. These five causes continue microevolution through generation to generation. Examples of four of these causes are on this website titled [|Mechanisms of Microevolution].

Genetic variation is another important aspect in the populations and its evolution. It occurs within and between populations and are characteristics in an individual such as the blood type in humans. But there are different kinds of characters, quantitative and discreet. Quantitative indicates a polygenic inheritance, an effect of two or more genes on a single phenotypic character. Discreet characters are determined by a single gene locus. Another aspect that is apart of genetic variation is polymorphism; it is where there are two or more distinct morphs which are easily noticed by its high frequencies. __Polymorphism__ occurs within populations. Between populations, there is geographical variation. Environmental factors cause change in the way a population interacts with its surroundings which changes the alleles that become dominant.

Polymorphism:

The theory of evolution where prime apes evolved into humans.
 * Evolution Cartoons:**

Effects of genetic drift