Below are seven statements related to the observation that many songbirds learn to sing their species song, instead of producing it "automatically" when they are mature. Label each following statement as either a hypothesis, (H), or a prediction, (P).
a. Male white-crowns learn their song early in life in order to demonstrate their brain quality to potential mates later on.
b. Brain development should be negatively affected by poor growth conditions early in life.
c. We expect females to approach taped songs recorded from males that grew up under excellent conditions.
d. Male birds that are able to learn their songs can mimic those of their immediate neighbours, which facilitates effective communication among rival males.
e. White-crown males that are deprived of food early in life ought not be able to copy the songs they hear as well as males that receive abundant food in the 10-50 day-old stage.
f. Young males that leave their birthplace should be able to shift the dialect they sing to match that of their neighbours in the new location.
g. By making reproduction dependent upon a learned skill, selection insures that only the truly superior white crowned sparrow males will reproduce, which helps eliminate harmful alleles from the species.
h. Which of the statement(s) a to g is/are based on group selection theory?
2. When a tropical moth is touched on the thorax it lifts its forewings up abruptly, exposing its brightly coloured hind-wings. What causes the moth to behave this way? For each explanation, first identify whether it focuses on a proximate or ultimate cause and label each explanation as G (genetic-developmental), P (physiological-psychological), EH (evolutionary history), or EF (evolved function). (10 marks)
a. The behaviour is instinctive.
b. Wing flipping scares some predators away.
c. The behaviour is the product of a special set of muscle contractions.
d. The behaviour is a modified version of wing movements that many moths use to raise their body temperature in order to begin flying.
e. Automeris moth genes influence the way the adult animal's nervous system forms connections between its muscles and its wings.
3. Which of the following statements is/are based on group selection theory? Male white-throated sparrows sing in the springtime because:
a. This is the best way to keep the species' population from getting too large.
b. Singing males attract mates in the spring.
c. This enables females to pick the best males, thereby improving the genetic quality of white-throated sparrows.
d. This enables a female to pick the best male possible, thereby improving her chances of having viable offspring.
e. Females prefer males whose songs indicate that they belong to the right species to mate with.
4. Studying twins is valuable for an understanding of the genetic causes of behavior because: (2 marks)
a. The similarities between identical twins tell us that human behavior is genetically determined.
b. The differences between identical twins tell us that human behavior is environmentally determined.
c. A comparison of identical and fraternal twins enables us to test the hypothesis that some differences among individuals are genetically determined.
d. A comparison of identical and fraternal twins enables us to test the prediction that gene-environment interactions shape the development of human behavior.
5. What significance can we attach to the fact that the verbal ability scores of adopted children are more similar to their biological parents' scores than to their adoptive parents' scores?
a. It shows the importance of early experience in shaping a child's behavior.
b. It demonstrates that environments are really not that important in the development of a person's verbal abilities.
c. It constitutes a scientific conclusion, namely that the correlation between verbal ability scores of biological parents and the children that have been reared by others is about 0.35.
d. It is contrary to the following prediction: persons experiencing different environments should exhibit different behaviours.
6. Gene knockout experiments have been done to:
a. Tell us that animal behavior is dependent upon genetic information.
b. Create two categories of individuals that differ with respect to a single gene.
c. Test whether a given behaviour controlled by that gene contributes to the reproductive success of individuals.
d. Demonstrate that DNA is the molecule of heredity.
7. If an experimenter is able to artificially select for increased barking in
a population of dogs over four generations, then:
a. There must have been genetic variation relevant to the development of barking in the initial population in the experiment.
b. Barking is probably very important to the reproductive success of dogs.
c. We have proof that natural selection and artificial selection are somewhat different.
d. The experimenter has shown that if dogs were to go wild, the population would evolve toward a higher level of barking in nature too.
8. The statement "An adaptation is a trait whose fitness benefits (B) exceed its costs (C)" is false because an adaptation:
a. Can have higher costs than benefits if the trait helps the species survive.
b. Not only has to have B > C but it also has to improve an individual.
c. Not only has to have B > C but the difference between B and C has to be greater than any other alternative.
d. Not only has to have B > C but it also has to be more common than any other alternative in the population.
9. Match (a) and (b) with one of the following three terms (1-3).
a. Releaser
b. Innate releasing mechanism
1. Male wasp pounces on orchid flower petal
2. Odours coming from orchid flower petal
3. Hypothetical element of the wasp's nervous system
10. Study the following graph, which shows the tuning curve of crickets exposed to sounds from 3 to 100 kHz:
i. The "intensity threshold" on this graph refers to the:
a. Loudest sound of a given sound frequency that a cricket can hear.
b. Softest sound of a given sound frequency that a cricket can hear.
c. Most intense response given by a cricket to a given frequency.
d. Least intense response given by a cricket to a given sound frequency.
ii. What sound frequency can crickets hear most easily?
a. 3 kHz
b. 5 kHz
c. 20 kHz
d. 40 kHz
iii. The graph does not constitute a scientific conclusion because:
a. It does not contain the prediction that the data were designed to check.
b. It does not answer a causal question of any sort.
c. The data were gathered to test whether a prediction was correct prior to reaching a conclusion.
d. The data were collected only from one cricket and so are inconclusive.
iv. We could best use the graph to demonstrate "stimulus filtering" by making the point that:
a. Crickets cannot hear all sound frequencies equally well.
b. Individual crickets differ in their own intensity thresholds for sounds of different frequencies.
c. Crickets respond differently to sounds of different frequencies.
11. A spider researcher Pia Stålhandske knew that males of Pisaura mirabilis offer their mates a nuptial gift, a prey item, such as a cricket, whose acceptance by the female is critical for male mating success.
Males wrap their generally dark coloured gifts in white silk. Stalhandske wondered if the males wrapped their gifts in order to make them look like the white, silk-covered egg sacs that mated females make and hold in their jaws to protect until the spiderlings hatch.
i. The last sentence in the paragraph above constitutes:
a. A causal question
b. A hypothesis
c. A prediction
d. Test evidence
ii. What theory was Stalhandske using to explore this species' courtship behavior?
iii. Which of the following predictions might Stålhandske have felt was likely to be correct, given her presumption that males might be making their nuptial gifts look like eggs sacs?
a. The time for a female to accept a nuptial gift should be less for prey covered in silk that has been experimentally coloured brown instead of white.
b. Natural silk-covered prey should be comparable in light reflectance to silken egg sacs.
c. Females ought to be highly prepared to grab and hold silken egg sacs that had been taken from them but then offered back as if they were a nuptial gift.
Part B: Long Answer Questions
Based on what you have learned so far, consider THREE of the following questions. Write your responses in 200-300 words.
1. What features of language learning in humans are similar to song learning in birds? Do these similarities suggest certain hypotheses on the proximate bases of human language learning, especially the genetic and developmental components? Do comparisons with birds also suggest some interesting hypotheses on the adaptive value of learned language for members of our species?
2. In 1998, a team of geneticists claimed that men with two copies of the I allele of the ACE gene were much less able to improve their physical condition through exercise than people with a different allele (D) of this gene. According to these researchers, individuals with two copies of the I allele were very much underrepresented in groups of mountain climbers who climb to 7000 meters without oxygen. Dispute the claim that the D allele is a "gene for mountain climbing." What role does the environment play in the development of the biochemical product of the ACE gene? Why are many genes almost certainly involved in the development of a person who enjoys mountain climbing? How, then, could a single difference in the ACE gene potentially result in a difference in mountain-climbing behaviour between two people?
3. You may recall that the transition to foraging in honey bees depends on the makeup of the colony, such that if there is a shortage of nurse workers within the hive, older bees will delay their shift to foraging role. What prediction follows about per gene expression in the brains of these socially delayed older nurses relative to foragers of the same age from other colonies with numerous young nurse bees? Provide proximate and ultimate hypotheses for the fact that social interactions can alter circadian rhythms in honey bees-and even fruit flies, which do not live in highly organized societies.
4. Although natural selection is blind, the products of this process are often amazingly complex. In order to explain how a blind process dependent on random events (mutations) can generate such complexity, Richard Dawkins has provided us with an analogy [303].
He invites us to imagine that a complex current trait is like an English sentence; for example, a line from Shakespeare's Hamlet: METHINKS
IT IS LIKE A WEASEL. The odds that a monkey would produce this line by tapping at a typewriter are vanishingly small, one in 10,000 million million million million million million. These are not good odds. But if instead of trying to get a monkey or a computer to get the "right" sentence in one go, let's change the rules so that we start with a randomly generated letter set such as
SWAJS MEIURNZMMVASJDNA YPQZK. Now we get a computer to copy this "sentence" over and over, but with a small error rate. From time to time, we ask the computer to scan the list and pick the
Whatever "sentence" is closest is used for the next generation of copying, again with a few errors thrown in. The sentence in this group that is most similar to METHINKS...is selected to be copied, and so on. Dawkins performed the experiment and found that it took 40 to 70 generations to reach the target sentence-a few seconds of computer time, not years. What was Dawkins's main point in illustrating what he called "cumulative selection?" In what sense might you say that the sentence analogy more closely resembles artificial selection than natural selection?