Microevolution - Michael Nolff

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Microevolution - Michael Nolff


GENE POOL: the stock of different genes in an interbreeding population and also total genetic information in the gametes of all the individuals in a population

GENETIC DRIFT: the variation in the relative frequency of different genotypes in a small population, owing to the chance dissapearance of particular genes as indivuduals die or do not reproduce

BOTTLENECK EFFECT: A marked decrease in gene pool diversity due to a low number of genetically distinct individuals in the population

Non-random matingNon-random mating occurs when the probability that two individuals in a population will mate is not the same for all possible pairs of indivuduals. It can be in two forms: inbreeding and outbreeding. Interbreeding is more common because individuals are more likely to make with close relatives rather then different ones. Genotype frequency changes for ones who inbreed. Homozygous increases while heterozygous decreases. When individuals inbreed, all homozygotes produce homozygotes, and half of the offspring of heterozygotes are actually homozygotes. It increases frequency with homozygotes rather than heterozygotes since the frequency for heterozygotes is 50%.

MutationsThis is actually a weak force for changing allele frequencies, but strong for introducing new alleles. It is the ultimate source for new alleles in plant populations. Small populations only have few alleles due to genetic drift and also fewer mutations are only generated in a small population. Populations increase from forward mutation and some decrease from a backward mutaiton

Genetic DriftGenetic drift changes in allele frequency because it changes within a population change by chance. It is a process that could lead to very large changes in a short period of time. It leads to fixation in alleles or genotypes in populations. Drift increases the inbreeding coefficient and increases homozygosity as a result of removing alleles. This is common in populations that undergo regular cycles of extinction and recolonization. The frequency does not change in any predetermined direction, and this is also called "random drift" in such cases.

Gene FlowGene flow is especially another factor that effects gene frequencies in a population. Organisms migrate and when they do, alleles flow from one population to another and begin to interbreed in new localities, or when there is deliberate crossing of breeds or subpopulations within breeds.

Natural SelectionNatural Selection effects gene frequency a lot. The frequency may actually change from generation to generation. Natural selection will remove certain individuals from the population and if those individuals were of or were going to become of reproductive age, then that may remove certain alleles and possibly genes from the population. Also if certain phenotypes make an organism more fit than others, then allelic frequency of those genes will increase. So thats how it can affect gene frequency.

Allopatric Speciationspeciation that occurs when biological populations of the same species become vicariant, or isolated from each other to an extent that prevents or interferes with genetic interchange.

Sympatric SpeciationIt is the process through which new species evolve from a single ancestral species while inhabiting the same geographic region.Hybridizationthis generally refers to a molecular biology technique that measures the degree of genetic similarity between pools of DNA sequences. It is usually used to determine the genetic distance between two organisms.

Behavioral Isolationthis is a reproductive barrier based on behavior, usually in the form of mating rituals and signals. Signals that attract mates to each other may be one of the most important factors in determining whether closely related species mate with each other or not.Temporal Isolationthis means 'isolated in time', so this is a mechanism that prevents species from mating because they breed at different times

Geographic Isolationthis is a term that refers to a population of animals, plants, or other organisms that are separated from exchanging genetic material with other organisms of the same species. Typically this isolation is the result of an accident or coincidence. It is really animals or other living creatures being separated from mixing genes within their same species. So this seperates the species from one another


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