Questions for Chapter 4:1. Some small fishes have evolved an antipredator mechanism rather like those possessed by noctuid moths and cockroaches. In the case of the fishes, this system is based on two large neurons located on either side of a fish’s brainstem. The giant cells respond very rapidly to water disturbances that reach the side of the fish; the cell closest to the source of the disturbance fires more strongly, and the fish responds by turning away from the side more strongly stimulated. Hunting tentacled snakes form their bodies into a U shape in order to catch their prey. Small fish that happen to swim into the U-shaped bay formed by the body of the snake often turn towardthe mouth of the predator, facilitating their capture. Provide a proximate and an ultimate explanation for the fish’s behavior, which constitutes an obvious Darwinian puzzle.2. The blue tit (Cyanistes caeruleus) is a songbird with a blue patch of feathers that reflect ultraviolet radiation. Female blue tits apparently prefer to pair with males that have relatively bright UV-reflecting feathers on their crowns. But at least in one population, male blue tits whose crowns reflected less UV produced more offspring than males with more UV-ornamented crowns (Hunt et al. 1999). A research team suggested that males with low-UV crowns were better able to sneak onto neighboring territories and sire “extra-pair” offspring with their neighbors’ mates than were males with high-UV crowns. How would you test this hypothesis experimentally? List your predictions. 3. Homing pigeons (Columba livia domestica) are very good at returning home after being released in a strange location. Internal biological clocks play a role in this ability (Walcott 1972). You can reset a pigeon’s biological clock by placing the bird in a closed room with artificial lighting that comes on and goes off out of phase with sunrise and sunset in the real world. For example, if sunrise is at 6:00 AM and sunset at 6:00 PM, let’s set the lights in the room to go on at noon (6 hours later than the actual sunrise) and off at midnight (6 hours later than actual sunset). A pigeon exposed to this routine for several days will become clock-shifted 6 hours out of phase with the natural day. If taken from the room and released at noon30 kilometers due east of its loft, the bird will behave as if the sun had just come up in the east. Why then will the bird fly north instead of west?Chapter 5 Questions:1. Inhibitory neural messages often play a key role in organizing the behavior 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 (Loher et al. 1993). 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 behavior. How might inhibitory messages be involved? What is the adaptive significance of this proximate mechanism?2 You may recall that the transition to foraging in honey bees (Apis meliffera) 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 the foraging role. What prediction follows about pergene 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 (Levine 2004), which do not live in highly organized societies.