Introductory Biology Module 5 - Natural Selection and Ecology

Introductory Biology Module 5 - Natural Selection and Ecology

Why is the Hardy-Weinberg law useful?

There are five Hardy Weinberg laws and that are related to following factors:

No gene flow

Random Selection

Extremely Large population

No natural Selection

No mutation

These laws are useful because of the facts that these laws are regarding the evolution of the population. Provided that these rules are applicable, the evolution will not take place in the population. In case, if only one of these rules is not met evolution may be possible. It is the variations in the frequencies of gene over the time that leads to evolution. The principle of Hardy-Weinberg is a baseline for the determination of whether or not the gene frequencies have been changed in the population and therefore whether the evolution has taken place (Pojeta & Springer, 2001).

Define Genetic Drift

In biology, genetic drift is the variation in gene frequencies in a population due to change. It is also called neutral evolution. Genetic drift produces changes in gene frequencies, and these changes have different effects on the genetic structure of populations. First, genetic drift causes the gene frequency of a population change over time.

Despite all populations start from an allele frequency of 0.5, the frequencies of each population vary over time due to sampling error. The gene frequency may increase or decrease in each generation. Moreover, with the passage of time the frequencies wander randomly, i.e. they go adrift. Sometimes, by chance, the gene frequency reaches zero or 1 (Jorgensen, 2009).

What factors influence the mutation rate of a population?

Following are the factors that have influence on the mutation rate of population

Migration

Migration is the process of moving individuals from one population to another and then crossing the representatives of these two populations. Migration provides a "gene flow", ie change in the genetic composition of a population due to the arrival of new genes. Migration does not affect the frequency of alleles in the species as a whole, but local population's gene flow can significantly change the relative frequencies of alleles, provided that the "old-timers" and "migrants" initial allele frequencies are different (Anderson, 1997).

Random Genetic Drift

Any natural population is characterized by a finite number of individuals that belong to it. This fact manifests itself in purely random statistical fluctuations in gene frequencies and genotypes in the formation of gametes sample and this form a next generation. The rate of mutation is higher in random genetic drift because of highly variable gene selection.

Natural Selection

Natural selection is the process of differential reproduction of genetically different organisms in a population. Practically, this means that carriers of certain genetic variants are more likely to survive and leave offspring than other media variants.

Substitution of Genes

Substituting genes is the process by which the mutant allele replaces the initially dominated allele. In other words, as the result of different processes e.g., mutation, genetic drift, screening a population is formed only with mutant alleles. Mutant alleles are found in a population as a result of single gene ...