Biology 4218A Lecture Notes - Chromosome, Homologous Chromosome, Allele Frequency

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taupekoala915

23 Jan 2013

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The reproductive contribution of a phenotype to subsequent generations relative to the contributions of other phenotypes is called its fitness. The fitness of a phenotype is determined by the average rates of survival and reproduction of individuals with that phenotype. Sexual selection is a special type of natural selection that acts on characteristics that determine the reproductive success. An allele that does not affect the fitness of an organism is called a neutral allele. Neutral alleles are unaffected by natural selection. Neutral alleles tend to accumulate in a population over time, providing it with considerable genetic variation. Sexual recombination amplifies the number of possible genotypes. Sexual recombination generates an endless variety of genotypic combinations that increases the evolutionary potential of populations a long-term advantage of sex. Sexual reproduction allows natural selection to eliminate deleterious mutations from the population over time and may be especially valuable as a defense against pathogens and parasites.

Related Questions

One common misconception about evolution is that individual organisms evolve. It is true that natural selection acts on individuals: Each organism's traits affect its survival and reproductive success compared with those of other individuals. But the evolutionary impact of natural selection is only apparent in the changes in a population of organisms over time.

Using at least two examples, explain how the process of evolution is revealed by the imperfections of living things. Provide evidence based facts.

periwinkleshark456

1. Traits don't necessarily have to be passed on from parent to offspring for natural selection to act on them; traits that are environmentally acquired during the life time of an individual (such as practicing to become very strong or very fast) can also be acted upon by natural selection. Select one: True or False

2.Within the same species and even within the same population, not all individuals are the same. They vary in size, shape or other traits.

Select one:

True

False

3.Differential reproductive success means that some individuals in a population leave more offspring that survive and reproduce relative to other individuals in a population.

Select one:

True

False

coraldolphin670

In a population of flowers growing in a meadow, C1 and C2 are autosomal codominant alleles that control flower color. The alleles are polymorphic in the population, with f(C1)= 0.8 and f(C2)= 0.2. Flowers that are C1C1 are yellow, orange flowers are C1C2, and red flowers are C2C2. A storm blows a new species of hungry insects into the meadow, and they being to eat the yellow and orange flowers, but not the red. The predation exerts strong natural selection on the flower population, resulting in relative fitness values of C1C1 = 0.30, C1C2 = 0.60, and C2C2= 1.0.

a. Assuming the population begins in H-W equilibrium, what are the allele frequencies after one generation of natural selection?

b. Assuming random mating takes place among survivors, what are the genotype frequencies in the second generation?

c. if predation continues, what are the allele frequencies when the second generation mates?

d. what are the equilibrium frequencies of C1 and C2 if predation continues?

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Biology 4218A Lecture Notes - Chromosome, Homologous Chromosome, Allele Frequency

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