Evolution Test Review

The test will have some general questions on evolution, especially measuring evolution with applications of the Hardy-Weinberg equation. The test is over the following chapters: Chapter 18 (skip phylogenetic material, we will cover this in our next unit), Chapter 19 and Chapter 20 (look at influences that can lead to speciation, understand the biological definition of a species, and be able to distinguish between allopatric/sympatric speciation models).

Key Terms: Homologous structure, analogous structure, vestigal structure, divergent evolution, convergent evolution, parallel evolution, allopatric speciation, sympatric speciation, selective pressure, directional pressure, sexual dimorphorisism, natural selection, homoplastic features.

Here are a few sample multiple choice questions:

 

1. Which one of the following does NOT characterize a population at Hardy-Weinberg equilibrium?

a. large population size

b. no mutation

c. nonrandom mating

d. absence of gene flow

2. If the frequency of a recessive allele is 36 percent, the frequency of the dominant allele would be what percent?

a. 5

b. 8

c. 25

d. 40

e. 64

3. Members of two different bird species mate and produce viable fertile offspring. The courtship song of the hybrid offspring is not recognized by members of either parent species. This is an example of

a. speciation

b. balanced polymorphism

c. behavioral isolation

d. sexual selection

e. ecological isolation

Problems dealing with the Hardy-Weinberg equation would be as follows: A population of tigers display two morphs: orange (dominant) and white (recessive). In the parent generation, 86% of the population is orange.

a. What is the P and Q value for this generation?

b. If the next generation exhibits a Q value of 0.22, is this population at genetic equilibrium?

c. What percentage of the offspring generation would be heterozygous (if Q = .22)?

 

 

Answer: a) Take the square root of 0.14 (% of the recessive trait) to get the value of Q (=0.37). Since P + Q = 1, the value of P would be 0.63.

b) No, a Q value of 0.22 indicates that the prevalence of the recessive allele is falling in the population. A changing Q indicates that the population in changing and therefore not at a state of equilibrium.

c) If the Q value is .22, P must be .78. In the Hardy-Weinberg equation, the frequency of the heterozygous trait is 2PQ, or 2 X .22 X .78 = .34, or 34% of the population.