Part 1

Part 2

Part 3

1-1) Describe the three basic classes of hormone that can influence animal behavior.

1) Developmental

2) Primer

3) Releaser

b) Give a real-life example of a behavior that is influenced by one of these three types of hormones:

Many possible answers from lecture notes and the reading

1-2) Give an example of Classical Conditioning.

Pavlov's dog salivating at the ring of a bell that accompanied food is perhaps the best known example.... any situation in which both the conditioned and unconditioned stimulus precede the response.

b) Is this an example of associative or non-associative learning? Associative

1-3) Describe the four basic elements of a basic nervous system that are required for the adaptive expression of behaviors. Feel free to use a diagram if that would help.

These are REQUIRED:

1) Detection of information or signal (nerves)

2) Transmission of information (interneurons)

3) Processing or decoding of information (brain)

4) Response to processed information by muscles after signal from decoder

Doing all of this fast is an advantage, but not necessarily a requirement

1-4) Every biologist knows that genes make proteins, not behaviors. Is their any evidence that indicates a link between genetic makeup and the expression of specific behaviors? a) YES

If you answered yes, give a specific example:

Many possible answers: anything that linked a pattern of behavior with known similarity or dissimilarity in genetic make up was sufficient.

1-5 Give two examples of a "social" environmental cue

Any answers that show how the presence of other animals can influence how an animal behaves: e.g., Bruce effect, chemical signaling in ants, response to an alarm call, etc, etc....

2 - 1) Students of animal behavior may ask both "ultimate" and "proximate" questions about a specific behavior. What is the primary difference between these two approaches? Support your answer by providing an example of behavior that can be addressed from both perspectives.

Ultimate questions ask "why" animals behave as they do. Proximate questions ask "how" animals behave as they do. For example, consider bird migration: Proximate questions focus on how changes in day length induce hormonal changes that lead to different levels of activity and movement. Ultimate questions focus on why investing the time and energy to move from one area to another (costs) are outweighed by benefits of moving (e.g., increased food, decreased mortality, higher reproduction).

2-2) Dawkins discussion of "selfish" genes includes a section on the evolution of displays rather than all-out fighting. Using examples from your readings, explain why natural selection might favor animals to use displays rather than open aggression when contesting for resources. Be sure to consider both the potential costs and benefits of these two alternative strategies.

This is a four part question (costs and benefits of two different strategies). A good answer focused on the costs of fighting due to risk of injury (to both winner and loser) vs. the benefits of winning a resource. We would expect animals to avoid fighting if the costs outweigh the benefits. Dawkins points out that displays may provide useful predictors of outcome, allowing individuals to avoid the costs of fighting, so long as the display is an honest signal of fighting ability (e.g. size, speed, agility, etc). Costs of displaying are lower than those of fighting, so long as bluffing or cheating is not common.

3 - 1) Field mice maintain small, exclusive-use territories within meadows and shrub land. Females defend small feeding areas from other females. Males defend larger territories (that typically contain several female territories) from which they exclude all other males. Despite their nocturnal habits, both sexes are at high risk from predators such as owls, cats, and weasels. Given what you know about the various means that animals can communicate, how and when do you think these mice signal each other with regard to: a) members of the same sex; and b) members of the opposite sex. Hypothesize both on the sensory modality used for communication, and upon the structure of the signal (duration, locatability, etc). Answer separately for males and females.

Keys to this question: identifying the sensory modality given the costs and benefits of each. Thus, to answer well, you should initially indicate which have the potential to work: Vision and Electric won't work (its dark and above water). Territoriality means spread out, so tactile (which works only under extremely short distances) seems unlikely to be used unless animals are right next to each other (mating, fighting). That leaves auditory and chemical signaling. Both work at night and can be transmitted around objects (don't require line of sight), but auditory is relatively costly (both in terms of energy expenditure and risk of predation) and very short term when compared to chemical signaling (which has the advantage of being locatable, but the animal does not have to be present at the source of the signal at all times (good for anti-predation)

In the context of same-sex communication, this is basically territory maintenance... In the context of intersexual communication, this is basically reproductive signaling. For both, chemical signals work for the above stated reasons, plus they have the added advantage of giving information on both presence/absence (last time since marking) and physiological state (reproductive condition, etc). Thus, chemical signaling seems the most likely to be adaptive, and, indeed, field mice rely heavily on pheromones for communication.

 

3 - 2) It is clear that some behaviors are primarily "learned" while others are primarily "innate" or "instinctual". The expression of these different types of behaviors carry distinct costs and benefits, depending on the environmental context in which they are performed. Below, using example(s) of real animals, describe the various costs and benefits associated with the expression of "learned" and "innate" behaviors. It may be helpful to define a specific environmental context to which behaviors can be deemed "appropriate" or "inappropriate".

This question is all about the relative costs and benefits of innate vs learned behaviors. The best answers listed these:

Innate behaviors are good because the are: fast, require little information processing (brain, memory, etc), and can be done "correctly" the very first time. The term "correctly" depends upon environmental context however, and this highlights the main problem with innate behaviors... they are a "gamble" that the organism will experience a stimulus in the correct context.

Learned behaviors are good for this reason: they allow organisms to develop responses to environmental stimuli based on feedback relative to context. The costs of learning may be large, however, since they require mistakes to be made during the learning process. These mistakes can be extremely costly (e.g., not recognizing a predatory). Additionally, learned behaviors require neuronal systems for processing and memory, and time to learn. These can both be considered costs.

There are many examples that highlight these differences... some responses were hypothetical examples, but the question asked for "real" animals.

 

3-3) Male fiddler crabs are notable for their one extremely large claw. Males use this claw to fight with other males and to attract prospective mates using a waving display.  Claw size, among other attributes, is known to be an important determinant of female choice and male dominance in fights. Males that lose this claw grow a replacement that is identical in form to the original. Replacement claws are, however, lighter and less robust, making them less effective as a fighting weapon.  Males with original claws do not differentially fight males with replacement claws, even though they are likely to win.  Females show no preference for males with original claws.
In the context of what you have learned in this class, would you consider the behavior of males with replacement claws to be honest or deceitful?  Below, justify your answer in as much detail as possible. Hint: a good answer will clearly define what is meant by “honest” and “deceitful” in this particular example and will include a careful consideration of the potential costs and benefits associated with the information being sent and received.

An honest signal conveys accurate information about the state (quality) of a sender, from the sender to a receiver. Theory suggests that honest signals must be costly to be reliable indicators of state (quality), otherwise, nothing would prevent lower quality individuals from making the same signal (cheating), reducing the reliability (and making for a dishonest signal). A claw that is lighter and less robust is presumably less costly to make and also less effective as a weapon. If a male with a replacement claw is not attacked preferentially by a male with an original claw, then there is an increase in net benefit whenever the attack does not take place. This occurs because: A) they do not incur additional costs from having more/costlier fights while simultaneously using a less costly “signal” and B) these males are still chosen non-preferentially by females for mating. This indicates that the signal is a dishonest signal that is somehow “bluffed” successfully by males with replacement claws.

A complete answer to this question must also consider the additional costs accruing to receivers (males and females). For males, there is presumably a cost with not detecting the type of claw their opponent has (inferred from the lack of preferential attacks upon replacement claw males), since males with original claws should win encounters with replacement claw males. For females the situation is less clear, since a males with replacement claws might or might not represent a cost in terms of mate choice. There is insufficient information to know, however you could argue it either way if you supposed specific conditions (e.g., good genes/bad genes ideas, etc), although the potential success of deceitful “sons” might lead to increased fitness for females, as well as males.

 

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