Question

1. Which of the following modes of evolution would be considered adaptive evolution? Explain why or why not. a. Genetic drift b. Natural selection
2. In the wild, various sperm and egg cells must navigate a complex environment to complete fertilization. There are mechanisms in place at the molecular level to guard against interspecies fertilization, even between very closely related species. Some of these mechanisms involve lock and key functions of interacting proteins. These molecules most likely regulate which type of reproductive isolation mechanism? Please explain.
3. Describe an example of non-heritable variation. Think about the way an organism interacts with its environment and how that influences its phenotype (the nurture in nature vs. nurture). Knowing what you do about genetics, genes, and gene expression control, propose a mechanism of molecular control that might be working in the example you have chosen.

Answer 1

1. Answer: Option B is correct
Explanation:
Genetic drift = Variation in allele frequencies due to chance events
It is not adaptive evolution as the abundant allele after genetic drift may not be adaptive.

On the other hand, natural selection is the driving force of adaptive evolution.
It selects alleles that provide a selective advantage to the prevailing conditions.

2. Reproductive isolation mechanisms that prevent fertilization = Pre-fertilization isolation mechanisms/Pre-zygotic isolation mechanisms

3. Nonheritable variation = A trait that is acquired during the lifetime of an individual which is not caused by changes in the germline
Ex: Playing piano, Swimming, and somatic mutations

An organism's phenotype is the collective outcome of interactions between its genotype and the environment.
P = G + E
The environment can create a phenotype not caused by the genotype
Ex: A malnourished kid appears as if he is suffering from a genetic mutation

The environment can also suppress a phenotype caused by the genotype
Ex: Diabetic patients do not exhibit symptoms if they are administered with Insulin injections regularly.