Biology 1002B Lecture Notes - Lecture 11: Genetic Recombination, Microevolution, Genotype Frequency

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3 Feb 2017

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Almost all of the variability in mtdna comes from chance mutations that occur at a steady rate, rather than from genetic recombination. Microevolution is a change in frequencies of alleles or heritable phenotypic variants in a population over time. A population of organisms includes all the individuals of single species that live together in the same place of time. When scientists study microevolution, they analyze variations. Population geneticists first describe the genetic structure of a population. Genetic structure of populations: in diploid organisms with pairs of homologous chromosomes, a(cid:374) i(cid:374)di(cid:448)idual"s ge(cid:374)ot(cid:455)pe i(cid:374)(cid:272)ludes t(cid:449)o alleles at ea(cid:272)h ge(cid:374)e locus. The sum of all alleles at all gene loci in all individuals is (cid:272)alled the populatio(cid:374)"s gene population: the genotype frequencies are the percentages of individuals possessing each genotype. They can then calculate allele frequencies, the relative abundances of the different alleles: allele frequencies represent the commonness or rarity of each allele in the gene pool.

Related Questions

Which of the following statements is true about the theory of evolution?

The focus of the theory of evolution is to explain the origins of life.

According to the theory of evolution, life evolved entirely randomly.

The focus of the theory of evolution is to explain how life diversified from the first living cells.

According the theory of evolution, only the strongest and toughest can survive.

Which of the following best explains our current understanding of microevolution?

Neither microevolution nor macroevolution can be observed within a human lifespan?

Microevolution is the gradual change of the genetic makeup (allele frequency) of a population over time.

Microevolution and macroevolution occur by very different mechanisms

Microevolution is the evolution of small organisms; macroevolution is the evolution of large organisms.

The Irish elk is a giant species of deer that went extinct about 5,000 B.C. They are well-known for their extremely large antlers (12 feet wide) in males. The antlers likely played some role in protection against predators, but another possible cause for their large size could be

blending genetics

sexual selection

spontaneous generation

inheritance of acquired characteristics

Cross River gorilla is listed as critically endangered species. With only 35 of these gorillas in the world, they are at risk of extinction largely due to poaching and loss to diseases such as Ebola. Genetic studies of the remaining gorillas show very little variability, because several alleles were likely lost due to ______.

		genetic drift
		gene flow
		increased rate of spontaneous mutations
		adaptive radiation

Need help with evolution questions:

1.) A haplotype is best defined as the ________________.

	haploid genotypes of all the gametes produced by a diploid individual

ABO blood type conferred by an individual gamete

genotype of either the paternal or maternal chromosomal complement

multilocus genotype of a chromosome or gamete

2.) Which of the following statements regarding linkage disequilibrium is true?

Exists when D is less than zero, but not when it is greater than zero.

Is reduced by sexual reproduction.

Is increased by crossing-over during meiosis.

Is increased by any random sampling error that happens to create or destroy certain chromosome genotypes but not others.

Is reduced by selection that favors certain combinations of genotypes.

3.) Selection on multilocus genotypes in random-mating populations leads to linkage disequilibrium when _______________.

it reduces mutation rates

it eliminates all haplotypes from the population

it prevents crossing-over during meiosis

some allele combinations confer greater fitness than do others

4.) When two loci are in linkage equilibrium, the allele carried on a chromosome at one locus is independent of the allele carried on the chromosome at another locus. When this is the case, _________________.

allele frequencies will not change over time

the two loci (or, more specifically, their protein products) do not interact

the frequency of each haplotype can be calculated by multiplying the frequency of its two alleles

all possible haplotypes occur at equal frequency

5.) Which of the following accurately characterize(s) Muller's ratchet model for the selective advantage of sexual reproduction?

Drift establishes linkage disequilibrium because multilocus genotypes with few mutations are eliminated by chance events.

In populations without sexual reproduction, deleterious mutations accumulate, eventually imposing such a burden that the population goes extinct.

Sex is favored selectively because it recreates the zero-mutation genotypes lost due to drift.

All of the above correctly characterize Muller's ratchet model for the evolution of sexual reproduction.

6.) The genetic signature of recent positive selection on a locus is _______________.

high frequency and low linkage disequilibrium

low frequency and low linkage disequilibrium

low frequency and high linkage disequilibrium

high frequency and high linkage disequilibrium

7.) Sexual reproduction is advantageous both in changing environments and in constant environments, compared to asexual reproduction.

True

False

8.) Sexual reproduction causes genetic recombination via crossing-over, which combines genotypes from different parents.

True

False

9.) One reason sex may be maintained in natural populations is proposed by the "Red Queen Hypothesis", which states that.....

genotypes created by sex are created by natural selection over and over

recombination creating novel genotypes that can resist infection by parasites

mutation load is reduced by novel adaptive mutations

the ability of sex to fix multiple

Biology 1002B Lecture Notes - Lecture 11: Genetic Recombination, Microevolution, Genotype Frequency

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