Darwin’s natural selection was based on the idea that selection acted upon the small difference between individuals, not large differences as many other believed. Darwin’s idea of natural selection also different in that he felt that selection acted on individuals, not groups or stocks which is what others had thought to be true. 

Another answer

Darwin’s idea of natural selection differed from other, first, in that he believed that variation occurred on an individual level as opposed to at a group level. Essentialism said that a specific group possessing a trait would live or die depending on the “fitness” of that trait. This opposed Darwin’s notion that small variations among individuals were the “raw material”. Secondly, essentialism reported that if variations were passed on or inherited, they came from rare macromutations whereas Darwin supported the idea of small, continuous variations as the determinants of the process of natural selection.

2. 

1. A domain is a region in a protein that either performs a specific function or is distinguishable as a structure different from other structures. Many, many genes may have a common domain which leads to domain shuffling. In this mechanism, introns and exons are involved. Shuffling occurs when exons are paired together. However, only symmetric exon pairs, such as exon 1 type, with exon 1 type, will result in a normal gene. Any other type of shuffling will cause a frameshift, and a new gene will result.

Another answer

1. Domain shuffling is the process by which a segment of a gene is moved to another segment on the chromosome. This can cause a rearrangement of DNA sequencing that ultimately creates a new gene.
   
   
2. Another mechanism for the origin of new genes is gene duplication. This mechanism occurs when a mistake is made by proteins during recombination, or crossing over, which causes the genes to unequally cross-over. The new gene is formed b the two chromosomes not matching up correctly. A mechanism which results in a new biochemical function is alternative splicing. Alternative splicing yields a new polypeptide produce when there is a “cut-off” during transcription of the mRNA.

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2. Gene duplication is one mechanisms that can create new genes. It occurs when a gene unnaturally duplicates itself. This duplicated gene is then subject to its own mutations. One mechanism for new biochemical functions of a gene is domain sharing, when the same protein produced by the same gene has different functions in different parts of the organism, e.g. crystalline protein.
   

3.

Mutations are random with respect to the environment. For example, an individual does not have a greater chance of acquiring a heat tolerant mutation in a warm climate any more than in a cold climate. However, there are many ways in which mutations are not random. In a DNA nucleotide, there are positions know as “hot spots” where mutations are more likely to occur. G and C are more likely than A and T. Also, transitions are more likely to occur than transversions even though more transversions are possible.

Another answer

Mutations are random in respect to the environment. The environment does not direct which mutations will arise or when or where they will arise from. Mutations are not random in many statistical cases. These tend to be “hot spots” areas where mutations tend to clump up. Mutations are also found to be non-random due to the structure and location of nucleotide sequences. Certain nucleotide sequences tend to experience more mutations than others. 

4.

1. Selection is the association of a phenotypic trait with a particular fitness level. It is distinguished from fitness because it encompasses botht he phenotype and the fitness of the individual with that trait. Fitness only encompasses a value of the individual’s contribution to the next generation -- not the particular trait that determines the contribution.

1. Selection is the covariance of a trait with fitness. Fitness is what an individual contributes to the next generation.

2. Direct selection is the causal association between a trait & fitness. The trait is directly influenced by the particular agent of evolution. But in indirect selection, it’s an inadvertent association between a trait and fitness due to correlations between trait. Therefore, an agent of evolution would indirectly affect 1 trait by directly affecting another trait simply because there was a correlation between the two traits.

2. Direct selection is the association of a trait with fitness in selection (i.e. larger fish acquire more males).  Indirect selection is the inadvertent association of a trait with fitness due to the interactions of another trait (i.e. longer legs on a frog require longer development time).
   

5.

1. D = .0025-.2025 = -.2.  No. The population is in gametic disequilibrium because D does not equal zero.
   
   
2. 0.5 = P + .5 H
   
   
3. Yes - They will exhibit the Hardy-Weinberg properties for their allele and genotype frequencies. All the assumptions are met - large population, no mutation or selection, and random mating. Gametic disequilibrium does not preclude Hardy-Weinberg equilibrium.
   
   
4. He says there’s hidden genetic variation which means we’re not seeing all possible genotypes in the proportions we should. The key to this phenomena is gametic disequilibrium. Since there is gametic disequilibrium there is hidden genetic variation or phenotypes that we don’t see. The allelic variation is present, but the genotypic variation is missing because we do not see all the possible combinations of alleles across loci. Genotypes are missing.

Another answer

4. If there’s gametic disequilibrium (which there is), then there’s a strong probability of having hidden genetic variation. This means that there are more genotypes possible than are being expressed, therefore a continuous trait could be hidden.

Note: Many students did a “Data Dump” on 5d. If you gave the correct answer, but included other information that wasn’t pertinent to the question, then you probably missed at least one point.

6. 

1. The present genotypic variance is different from what it was in the initial colonists. The initials were all heterozygotes (A1A2). The new colony now includes homozygotes (A1A1, A2A2). The distribution has spread out more -- there is more genotypic variation.

Another answer

1. Initially, Vg = 0 + 1*(8-8)^2 + 0 = 0

Now Vg = (10-8)^2 * (.25) + (8-8)^2 * (.5) + (6-8)^2 * (.25) = 2

The genetic variation is different. It has gotten bigger because the genotypes of the colony changed from all being the same having a mixture of 3 genotypes; the more genotypes present, the more Vg.

2. The genotypic variance is stable now because the animals are randomly mating, and there is no selection, no mutation, and there is a large population. They are in Hardy-Weinberg Equilibrium.

Another answer

2. Because the colony is in Hardy-Weinberg equilibrium. This means that the allelic frequencies are stable and will not change from generation to generation.
   

Bonus

1. Yes - if the alleles for the second trait is tightly linked to the first trait on the chromosome and segregates with this first allele for non-independent assortment and recombination.
   
   
2. I believe so, it all depends on the direction of the biochemical pathway. If the A product, or trait, occurs firs in the biochemical pathway, and the B product follows, selection for A indirectly selects for B. However, if the B produce (or trait) is selected only, and there is an available precursor that does not require the presence of the A product (trait) to complete the pathway, B could be selected for directly and independent of A.