Bio 178 Lecture 31. Mutation and Evolution of Populations. J. Elson-Riggins. Reading. Chapters 20 (P 410-411) & 21. ?. Quiz Material. Questions on P 432 & 452 Chapters 20 & 21 Quizzes on Text Website (www.mhhe.com/raven7). Mutation. Mutation.
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
Mutation and Evolution of Populations
Changes in the hereditary message of an organism.
Not inherited, but can have a profound effect on the individual, eg. Cancer.
Starting point for evolution - mutation produces new alleles and recombination shuffles them.
Do all Germ Line Mutations Increase Genetic Fitness?
No - May reduce, maintain, or increase progeny number.
Changes in Gene Position (Recombination)
1 (a) What are the consequences of changing the sixth base of the following DNA sequence to a “C”? 3-TACAATGGTATT-5
(b) What are the consequences of deleting the sixth base?
Change in species over time (descent with modification).
The process by which individuals (with characteristics that are advantageous in a particular environment) produce more offspring than other individuals.
Over time, the population will become better adapted to the environment.
Lamarck - Variation is acquired during the lifespan of the organism and passed on to the offspring.
When a gene in a population has more than one allele present at frequencies greater than would occur by newly arising mutations alone.
Can be studied at the DNA level by sequencing the DNA of population members.
The proportion of each allele type in a population.
1908 - Hardy and Weinberg determined why genetic variation persists in populations.
When the allele frequencies do not change through the generations - zero evolution.
Will occur if:
Mating is random.
Population size is large.
*Allele frequencies will not change if a population is in Hardy-Weinberg equilibrium.
p2 + 2pq + q2 = 1
Where p = frequency of most common allele.
q = frequency of less common allele.
A population of 200 cats is composed of 168 black individuals & 32 white individuals. Black (B) color is completely dominant to white (b) color.
What proportion of the population would be expected to be (i) heterozygous (ii) homozygous dominant?
In a population of red (dominant) and white flowers, the frequency of red flowers is 91%. What is:
The frequency of the red allele?
The frequency of homozygous dominant individuals?
The frequency of heterozygous individuals.
Allele frequencies in a population can be altered by:
The ultimate source of genetic variation.
But…occurs at a very low rate is not an important factor in the evolution of populations - the other factors have a greater effect.
Movement of alleles from one population to another.
Maintenance of new allele frequencies are dependent on whether the migrating individual(s) can adapt to the new environment.
1. Assortative Mating
When phenotypically similar individuals mate.
Increases the proportions of homozygotes.
2. Disassortative Mating
When phenotypically different individuals mate.
Increases the proportions of heterozygotes.
Random change in allele frequencies of a population as a result of chance events.
One or a few individuals leave a population and establish a new one.
The alleles of these founders will be very significant in the new population, even if they were rare in the original population.
Eg. Galápagos Islands.