1. A hummingbird species feeds almost exclusively on the nectar of Heliconia flowers. Each hummer has a circuit that takes it from one plant to another, with the bird showing up regularly at a given flower after a set period. It could be 30 minutes more or less to do the roundtrip.
a. In one sentence, explain why this statement could be wrong: "The bird is behaving optimally because it is getting more energy than it is expending on the foraging trips."
b. I want to collect information in order to determine if the bird is really foraging optimally in an energy gathering sense. What aspects of its foraging behaviour would I need to know and measure in order to calculate the net caloric gain for the foraging hummer?
c. Hummingbirds have been observed to hesitate before inserting their beaks into heliconia flowers to feed. How might this hesitation still be consistent with an optimal foraging hypothesis?
2. Polyandry in females might be advantageous if polyandrous females were to secure some genes from their several partners that were especially compatible with the genes in their eggs. What prediction follows from this hypothesis?
a. Females will typically choose the same very few males to be their sexual partners.
b. The mating system of males in a species of this type is more likely than not to be lek polygyny.
c. Polyandrous females should secure more material benefits from their mates than monogamous females.
d. The mating partners of females will vary substantially from female to female.
3. Behavioural ecologists have concluded that the ecology of females has more to say about the evolution of the mating system of a species than the ecology of males because
a. Receptive females are usually in short supply for males, not the other way around.
b. Male competition for mates is relatively unimportant in the definition of animal mating systems.
c. Females are the key for the preservation of the species; their reproduction, not that of males, determines the size of the next generation.
d. Females are almost always widely distributed and are difficult for males in search of mates to find.les are almost alway
4. Observation: You observe "shaky leaf walking" in a video of 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 works 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 from this hypothesis 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 (use a legitimate example of the comparative method based on the phenomenon of convergent evolution).
d. State a prediction that could be tested via the comparative method (use a legitimate example of the comparative method based on the phenomenon of divergent evolution).
e. State a prediction that illustrates the illegitimate use of the comparative method. After stating your prediction briefly, explain why this prediction would not be accepted by many behavioural biologists.
5. 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.
6. 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.
7. A hawk called the lesser kestrel nests in colonies. In this species, young birds sometimes move to the nests of adults other than their parents, perhaps because their parents are failing to rear them properly. The researchers found the following:
(1) The adopted nest-switching nestlings are not in poorer condition than those that stay in their natal nest.
(2) The adopted nestlings are not fed at a higher rate than they had been prior to the switch.
(3) The adoptees do not become top dogs in the dominance hierarchy among chicks in the new nest.
a. These data were collected to test a hypothesis. What was it?
b. What conclusion did the researchers reach from their work?
c. What relevance do you attach to the information that the lesser kestrel once nested on small cliff ledges but now often nests on rooftops in towns and villages?
d. On the basis of your answer to Question c, explain why adult lesser kestrels are so willing to adopt the offspring of other kestrels.
e. Rough-winged swallows will adopt the offspring of other swallows when parents are experimentally given these nestlings, just as lesser kestrels do when nesting on roof tops. This kind of similarity has a label; what is it and why might these two species behave similarly?
Part B: Long Answer Questions
Answer the following questions. Write your response in 200-300 words.
1. Some males of the white-ruffed manakin of Costa Rica move temporarily to lower areas while others skip migration to stay in the higher-elevation breeding locations. Birds that stay have greater mating success than those that leave. So why do any males migrate? Use conditional strategy theory to make some predictions about the age and condition of the birds that leave the breeding area.
2. Recently Sonia Altizer and her colleagues have found that the monarch butterflies that travel the longest distances have the lowest levels of infection by a protozoan parasite, whereas the prevalence of these parasites is highest in the nonmigratory populations of the butterfly. They suggest that because badly infected individuals cannot reach distant destinations, migration has the beneficial effect of culling parasite carriers, which keeps the species healthier than it would be otherwise. According to this hypothesis, who benefits from the removal of infected monarchs? From a theoretical perspective, why does this matter?
3. Inhibitory neural messages often play a key role in organizing the behaviour of an animal, as the mantis demonstrates. Mature female crickets (Gryllus bimaculatus) approach chirping males. About one hour after mating, during which the male transfers a spermatophore to his partner, the female stops tracking the calls of males of her species. If you found that emptying the sperm storage organ caused the female to resume responding to calling males, you could speculate on how the female cricket's nervous system controlled this aspect of her behaviour. How might inhibitory messages be involved? What is the adaptive significance of this proximate mechanism?
4. Although the number of cases of mate choice by females dwarfs the known examples of choosy males, that rarer form of mate choice does occur and may be more widespread than often appreciated. In this light, why might it be adaptive for male jungle fowl to enhance the speed with which their sperm can travel when roosters inseminate attractive versus unattractive females? Why might male potbellied seahorses (see Figure 8.4) strongly prefer to court large females, whereas females show no such preference for large males? And why might male black widow spiders bias courtship in favour of well-fed females as opposed to starved ones?