BIOL-3350 Chapter Notes - Chapter 11: Meiosis, Coevolution, Fecundity

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erindog825

12 Jan 2018

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Bacteria dont have male and females, the produce offspring simply by cell division - asexually since they have neither meiosis nor fusion of haploid gametes through fertilization. Hermaphrodites - an individual may develop both male and female organs/gametes. Reproduction - the formation of new individual organisms (offspring). It is made possible by genes that are subject to natural selection. Twofold cost of sex - asexual genotypes should increase in frequency replacing the sexual ones in the population. That is, natural selection should favor the evolution of asexual reproduction. Refers to the disadvantages of being sexual rather than an asexual organism. In sexual reproduction, beneficial mutations can be combined with other beneficial mutations, and they can be separated from harmful ones. Mullers ratchet - when asexual organisms acquire deleterious mutations that offset earlier, beneficial mutations, the two types of mutations can"t be separated/irreversible. The burden imposed by the accumulation of deleterious mutations.

Related Questions

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

BIOL-3350 Chapter Notes - Chapter 11: Meiosis, Coevolution, Fecundity

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