Part A:
1. Observation: You see "shaky leaf walking" in a Madagascaran mantid (one of about 1800 species, a member of one of dozens of genera of mantids, and a member of one of eight families of mantids). Hypothesis: The behaviour is effective because it makes the mantid look like a dried leaf blown about on the leaf litter of the forest floor or a trembling leaf on a low-lying shrub.
a. State a prediction that could be tested via additional observation.
b. State a prediction that could be tested via experiment
c. State a prediction that could be tested via the comparative method. (Example of legitimate use of the comparative method based on the phenomenon of convergent evolution.)
d. State a prediction that could be tested via the comparative method. (Example of legitimate use of the comparative method based on the phenomenon of divergent evolution.)
e. State a prediction that illustrates the illegitimate use of the comparative method.
2. Several hundred male bees sometimes gather to sleep on the dried stems of a shrub. A predatory assassin bug sometimes visits the bees and kills some as they are settling down. Present three different hypotheses on the possible adaptive anti -predator value of these sleeping aggregations. For each hypothesis, present a piece of evidence that would enable you to reject the hypothesis.
3. For each of the following traits, put NS if the trait is largely a product of natural selection and SS if the trait is largely a product of sexual selection.
a. The donation by a mother elephant seal of special nutrients and biochemicals other than DNA to her eggs.
b. A female starling's destruction of the eggs laid by another female that has been mated by the first female?s partner (if a male starling has only one mate, he will help her incubate the eggs).
c. The loss of all but two teeth in the jaws of ziphiid whales.
d. The enlargement of the two remaining teeth in the jaws of ziphiid whales.
e. The production and transfer of chemicals (in a male ejaculate) to a female fruit fly that increase the probability that the sperm transferred to her at the same time will fertilize her eggs.
4. For each of the following, put PI if the trait is an example of "parental investment." Put NO if the trait cannot be categorized as parental investment.
a. The donation by a mother elephant seal of special nutrients and biochemicals other than DNA to her eggs.
b. A female starling's destruction of the eggs laid by another female that has been mated by the first female's partner (if a male starling has only one mate, he will help her incubate the eggs).
c. The elaborate ornaments that a male bird of paradise possesses without which he will not attract a mate.
d. The transfer of large quantities of sperm to a female, which increases the probability that one of those sperm will fertilize the eggs.
e. The production and transfer of chemicals (in a male ejaculate) to a female fruit fly that increase the probability that the sperm transferred to her at the same time will fertilize her eggs.
5. Why might male Mormon crickets have a lower potential reproductive rate than females?
a. Males make relatively few sperm compared to the egg production rate of females.
b. Males compete so intensely for mates that this shortens their lifespan.
c. Males donate a very large, hard -to -replace spermatophore to each mate.
d. Females make almost no parental investment in their offspring.
6. Although some male crab spiders find and mate with adult female spiders, others that find immature females remain with them although the subadult females are incapable of mating until they become adults. This behaviour would puzzle most evolutionary biologists because:
a. The genetic basis for this behaviour would be very difficult to determine.
b. Mating is instinctive in spiders and therefore all males should behave the same, either mating with adult females only or guarding subadult females only.
c. Males that guard subadults cannot use the time to find receptive females.
d. One would think that immature female spiders should accept and store sperm from males in order to permit good female-finding males to have time to find many mates.
7. A conditional strategy is unquestionably an adaptation when individuals able to switch tactics:
a. Leave some surviving descendants to carry their genes into the next generation.
b. Leave more surviving offspring than individuals with any other strategy.
c. Are better able to adjust to changing conditions than other members of their species.
d. Experience a net gain in fitness from their behavioural flexibility.
8. Why do lions hunt together? Provide a one -sentence hypothesis that fits under each of the following categories (refer to Lessons 19 and 20 in Unit 6).
a. Mutualism hypothesis
b. Reciprocal altruism hypothesis
c. Altruism hypothesis
d. Selfish exploitation hypothesis
Part B
1. Take one possibly survival -enhancing element of bowerbird behaviour that could be the product of natural selection and anothersurvival -decreasing trait that might be the evolutionary result of sexual selection. For each, list the essential conditions that had to occur in the past for natural selection and sexual selection to occur. Is the factor "differences among individuals in age at death" on your list? Why or why not?
2. The manes of African lions vary in colour from very dark to quite pale. When two models of male lions, one with a dark mane and the
other with a light -coloured mane, were put out in lion territories, the males that found the models first approached the light -coloured one more often than the dark -maned model. In contrast, lionesses almost always walked close to the dark -maned model first. Peyton West and Craig Packer found that in general, mane colour was darker in older males and in those with higher testosterone levels [1275]. Knowing what you know about lion social behaviour (see Chapters 1 and 8) and sexual selection theory, how would you explain the differences in the reactions of males and females to the dark -maned models?
3. Among certain monkeys and apes with prolonged parental care, females live longer than males in species in which females provide most or all of the parenting, but males live longer than females in species in which males make the major contribution to offspring care [24]. In other words, adults of the parental sex tend to live longer than the nonparental sex. Does this finding indicate that parental care provides a fitness benefit for caretakers in the form of improved survival? Someone then claims that the longer life span of the parental sex has been selected for because primate young are very slow to develop, and therefore parents must live long enough to get their offspring to the age of independence in order to maintain a stable population. What do you have to say about that hypothesis? Do you have an alternative explanation for the observed pattern?
4. Territorial male bluegill sunfish defend the eggs and fry in their nests against predatory fish such as largemouth bass (see Figure 13.7 in the textbook). Figure 12.10 in the textbook shows how intensely males defended their nests in an experiment in which some territorial bluegills were exposed to potential cuckolds during the spawning season. Bryan Neff put sneaker males (see Figure 10.25 in the textbook) in plastic jars near the nests of his experimental subjects to provide the cues associated with a high risk of cuckoldry; he measured male brood defense by quantifying how intensely bluegill dads charged and threatened a predator of bluegill eggs and fry, a pumpkinseed sunfish, which Neff placed near bluegill nests in a clear plastic bag [866]. How do you interpret the results shown in Figure
12.10? What is puzzling about them? Does it help to know that bluegill males can apparently evaluate the paternity of fry, but not eggs, by the olfactory cues they offer?