<span>tubulin, the microtubule protein</span>
Answer:
Genetic drift
Explanation:
Genetic drift is defined as the random change in allelic frequencies from one generation to the other.
Genetic drift is an evolutionary mechanism in which the allelic frequencies in a population change through many generations. Its effects are harder in a small-sized population, meaning that this effect is inversely proportional to the population size. Genetic drift results in some alleles loss, even those that are beneficial for the population, and the fixation of some other alleles by an increase in their frequencies. The final consequence is to <u>randomly</u> fixate one of the alleles. Low-frequency alleles are the most likely to be lost. Genetic drift results in a loss of genetic variability within a population.
Genetic drift has important effects on a population when this last one reduces its size dramatically because of a disaster -bottleneck effect- or because of a population split -founder effect-.
Birds, insects, and many reptiles excrete nitrogenous waste in the form of uric acid, which saves water.
Nitrogenous waste in the body tend to form toxic ammonia, which must be excreted. Mammals such as human excrete urea, while birds, reptiles, and some terrestrial invertebrates produce uric acid as waste in the form of a white paste or power. The production of uric acid involves a complex metabolic pathway that is energetically costly in comparison to processing of other nitrogenous wastes such as urea or ammonia, it has the advantages of reducing water loss and, hence, reducing the need for water.
Answer:
The options
a. New combinations of genes yielding genotypes of greater fitness
b. Few heterozygotes because of underdominance
c. Frequency-dependent selection, leading to fluctuations in fitness
d. Heterozygotes with greater fitness, owing to overdominance
e. A random assortment of genotypes because of genetic drift
The CORRECT ANSWER IS b.
b. Few heterozygotes because of under dominance
Explanation:
In genetics, underdominance (at times called "negative overdominance") is the opposite of overdominance.
It is the selection against the heterozygote, that leads to disruptive selection and divergent genotypes. It occurs in cases of inferior and reduced fitness (As in our case study, it is the different chromosomal fusions and inversions)
of the heterozygotic genotype to the dominant or recessive homozygotic genotype. It is unstable as it causes fixation of either allele.
Another example is the African butterfly species Pseudacraea eurytus, which makes use of Batesian mimicry to avoid predation. This species carries two alleles that gives a coloration that is alike to a different local butterfly species that is harmful to its predator. The butterflies who are heterozygous for this trait are observed to be intermediate in coloration and thus encounter an higher risk of predation and a decrease in the total fitness.
