Ecol assignment 6

What is the fitness of a cooperator in mixed group type CCD for the payoff matrix and assumptions given in the study guide for the March 14 lecture.

2/3 x 7 +1/3 x 1=5

When an interviewer asked evolutionary biologist J. B. S. Haldane if he would risk his life to save a drowning man, he reportedly answered, "No, but I would for three brothers or 9 cousins." On this logic, what is the minimum number of nieces or nephews Haldane would risk his life for?

5

Fill in the blanks with words from the following list: development, between-group selection, heritability, heritable, variation, fitness, reciprocation, conflict mediation, cheating, multi-level selection, Prisoner's dilemma

A unit of selection and adaptation (i.e., an evolutionary individual) must possess heritable variation in fitness. Additionally, mechanisms of conflict mediation help prevent cheating at the lower level.

Which of the following is/are correct concerning the multi-level selection model discussed in class? More than one answer can be correct and all or no answers may be correct. A) Frequency of defect D never decreases within groups B) Groups with more cooperators C are more productive C) Groups with more defectors D are less productive D) Cooperators C never increase in frequency within a group E) Frequency of cooperators C increases overall, if between-group selection overpowers within-group selection

All are correct

Among which of the following groups of organisms is tit-for-tat most likely to evolve?

Barnacles which settle down next to each other and interact for life

Which of the following statements regarding complexity is true? a) evolution always progresses toward increasing complexity B) increased complexity, once gained cannot be lost C) during an evolutionary transition in individuality complexity increases D) complexity once gained can be lost E) complexity has increased in some lineages

C D E

What would happen to the frequency of cooperators in the global population if all groups had 1 cooperator and 2 selfish individuals?

Decrease

Which group composition is most conducive to enhanced between-group selection? C and D refer to cooperate and defect, respectively.

Groups are composed of either all C or all D. No mixed groups.

Briefly explain your answer to the last question.

Groups with only cooperators have more offspring than groups with only defectors. This means that overtime the groups with only cooperators will become much larger than the groups with only defectors.

Charles Darwin was initially puzzled by the observation that worker honeybees die when they sting an intruder to their hive (the bee's stinger is ripped from the bee's abdomen, causing a fatal injury). Based on what you know about natural selection, why did this observation complicate Darwin's theory?

He found it hard to imagine how such behavior could evolve, since a defending worker's chance of survival is zero.

What would have happened to the frequency of cooperators in the global population if all groups were composed either entirely cooperators or entirely of selfish individuals?

Increase

How is information different from most physical resources?

Information does not become depleted by sharing

Suppose that an allele is present in blue-footed booby offspring that causes a nestling to share its food with its nestmate if it is not particularly hungry during times of adequate food availability. This gene imposes a fitness cost of 0.3 on those who carry it, while conferring a benefit of 0.4 on the sibling who receives the additional food. Will this gene increase in frequency if the two nestmates are always half siblings (with the same mother but different fathers)? Why or why not?

No, because rb - c < 0

In order for a game to be a true prisoner's dilemma, which of the following conditions must be met? P is Punishment for mutual defection, R is Reward for mutual cooperation, S is "Sucker's" payoff, T is Temptation to defect.

T > R > P > S

Briefly explain your last answer to the last question.

Within group selection favors defectors when groups are mixed. In this example, all groups are mixed. Cooperation decreases.

Why don't higher-level individuals formed by a major transition usually succumb to the cheater problem discussed in the class and in the text?

examples of mechanisms: kin selection, reciprocal altruism, tit for tat

The case of altruism illustrates an important principle, namely that what is advantageous at one hierarchical level may be disadvantageous at another level, leading to a conflict. Various features of modern organisms suggest the importance of such inter-level conflicts. Mammalian cancer is an example. Cancerous cells increase in frequency relative to other cell lineages within the organism's body. So a maladaptive feature of individual organisms is explained by selection at a lower hierarchical level, in the case the cellular level. Cancer...

is explained by selection at the cellular level being stronger than selection at the organism level