Question

1. Define 'proximate cause' of behavior and 'ultimate cause' of behavior. Describe two examples of proximate cause and two examples of ultimate cause of monogamy in prairie voles.

2. Describe what we mean by ‘conditional strategy’. Describe what we mean by ‘optimal behavior.’ (Don’t give examples of an animal using conditional strategy or optimal behavior, rather actually describe conditional strategy and optimal behavior). Describe, with the use of specific examples, how conditional strategy and optimal behavior “interact” for a group of males of a given species that can choose among alternate mating tactics when attempting to mate.

3. Define circadian rhythm. Describe the biochemical / physiological regulation of circadian rhythms. Discuss the influence of external environmental factors on circadian rhythms, and give an example of a situation with an animal that demonstrates the influence of external environmental factors on circadian rhythms? What is a free-running cycle? Give an example of a free-running cycle that clearly supports your definition. Discuss the adaptiveness of circadian rhythms to an animal, and the adaptiveness of circadian rhythm sensitivity to external environmental factors.

Answer 1

1.

Proximate cause of the behaviour explains how an organism behaves, physiological, psychological etc. The main focus is on the immediate cause of the behaviour.

Ultimate cause of the behaviour is why animal bahves in the way ot behaves which includes the evolutionary reasons behind the behaviour.

Proximate cause is an explanation which is aimed at how an organism behaves the way it is behaving.

Ultimate behavior is the answer why an organism behaves the way it behaves which is based on the evolution of the behavior.

Proximate behaviour of the Prieri voles monogamous behavior is the release of Dopamine which is involved in reward and addiction and the pleasure related to monogamous mating. There is experimental evidence to proove to this effect.

Ultimate cause of the behavior is lack of number of female in the region, which resulted in mating only with one mate by the male in order to keep the species alive.

2. When individuals adopt alternate strategy for reproductive behavior based on environmental conditions.

Not one reproductive strategy will give highest reproductive success but it is best for one individual organism.

In dung beetles, males there are major and minor males. Minor males have no horns and other traits for attracting the mate. But they have a big testis to produce more sperms to flood to gain reproductive success. The males with poor nutrition develop in to minor males. So the environment has resulted in the development of such a male. The individuals can be genetically capable of being both types of males. But environment has resulted in different types. So the alternate strategy helps in more reproductive sucess of both.

Optimal behavior maximizes the difference between costs and benifits of a decision. The dung flies are polygamous. A female can copulate with two males in shorter time interval. However the male which copulates later will have chances of fertilizing 80% of eggs where as the male copulating first will have 20% chance of fertilizing with eggs. So,longer the beetls spendds time with the female, better chances of its eggs getting fertilized. But, spending more time with one female will reduce the chances of finding another female for copulation. So if a cowpat is far apart there are more chances of the beetle remaining with the female increasing its chances of pasing on its genes to next generation. So an optimal bahavior ensures the reproductive success.