Chapter 12: Principles of Social Evolution

Question 1

Describe group living in termites

Answer 1

a huge number of tiny STERILE termites build a huge home for their 1 REPRODUCING QUEEN AND ONE KING.

Question 2

Phenomenon that allows the sterile tiny termites to built a home for the one queen and one king.

Answer 2

EUSOCIALITY: small number of reproductive individuals being helped by a bunch of sterile individuals.

Question 3

Why are eusocial groups even favored by natural selection?

Answer 3

sterile individuals often are related to be the reproductive members, so it does STILL GIVE THEM REPRODUCTIVE SUCCESS.

Question 4

Living in a cooperative group in which usually one female and several males are reproductively active and the nonbreeding individuals care for the young or protect and provide for the group

Answer 4

Eusociality. focuses on that non-breeding individuals/sterile individuals still get reproductive success by helping becasue they are related to the fertile insect/animals.

Question 5

eusociality often results in the evolution of a ___ system. What does this result in?

Answer 5

CAST SYSTEM. results in different morphological differences in members of the population (soldiers, queens etc).

Question 6

Outline the 7 major evolution transitions

Answer 6

1) replicating molecules to populations of molecules in compartments
2) independent replicators to chromosomes
3) RNA as both genes and enzymes to DNA and protein
4) prokaryotes to eurkaryotes
5) asexual clones to sexual populations
6) protists to multicellular organisms
7) solitary individuals to colonies with nonreproductvive CASTES (EUSOCIALITY)
8) primate societies to human societies.

Question 7

3 key features to all major evolutionary transitions

Answer 7

1) a transition of independent replicators to higher-level evolutionary units
2) the emergence of DIVISION OF LABOUR that allows greater efficiency
3) the emergence of NOVEL INHERITANCE SYSTEMS that allow information to spread.

Question 8

What is altruism

Answer 8

behavior that benefits others at a cost to the individual performing the behavior.

Question 9

T/F cowbirds are altruistic

Answer 9

false. they are considered to be a selfish species.

Question 10

provide an example of altruism in honey bees

Answer 10

a worker bee provides a suicidal sting to an enemy when there is an invader.

Question 11

example of altruism in eusocial an species

Answer 11

in colobopis saundersi, the soldier ants store a quantity of mucus glue-like substance. when they’re approached by a predator, the soldier goes out and explode themselves to release glue onto the predator.

Question 12

Wynne-edwards theory of group selection

Answer 12

groups or species with self-sacrificing (altruistic) individuals are more likely to survive than groups without altruists, leading to the evolution of GROUP-BENEFITTING ALTRUISM. Basically “for the good of the group”

Has been discredited because suicide on an individual level would be selected AGAINST by natural selection, even if it were beneficial to the group or species as a whole.

Question 13

Wynne-edwards suggested that individuals self-sacrifice “for the good of the species,’ whereas George williams agrued that:

Answer 13

Traits spread for individual advantage or FAMILIAL advantage, but not for the entire good of the species.

The presence of a hereditary trait (including a behaviour) and of the genes underlying the development of that trait, was much more likely to be determined by differential reproductive success of genetically distinct individuals instead of genetically distinct groups (altruistic vs not altruistic groups)

Williams argued that individual level selection trumped group level selection

Question 14

weakness of group selection

Answer 14

williams pointed out that the weakness of group seelction was that it undermined CHEATING. The genes of selfish individuals who cheat will be disproportionaly represented in groups of altruists because the cheaters (not as altruist) will most likley be the ones to breed if the others are self-sacrificing.

Ex/ seabirds lay only one egg. People thought this was done for the good of the group because these seabirds are still able to take care of two babies if you place another egg in the nest.
It is actually in their self interest to raise one chick at a time because it is really hard to raise two puffins at once, often resulting in death of the parents.

Question 15

T/F: group selection theory (wynne-edwards) can explain lion infanticide

Answer 15

false. Group selection cannot explain why male lions kill cubs that aren’t theirs. This does not benefit the entire species.

If group selection was true, the male lions should kill all cubs indiscriminately in order to REDUCE STRESS ON RESOURCES, but they keep their own cubs alive. This Is a selfish phenomenon

Question 16

Hamilton’s theory was based on the premise that some species demonstrate altruism or eusociality beause relatives tend to:

Answer 16

share genes by recent common ancestry. Personal reproduction results in DIRECT selection, but assisting close kin other than one’s own offspring is an INDIRECT route to the same end: propagating identical genes.

Question 17

what does the coefficient of relatedness refer to?

Answer 17

r refers to the probability that an allele in one individual is present in another because both individuals have inherited it from a recent common ancestor

Question 18

r of siblings

Answer 18

0.5

Question 19

r of half siblings

Answer 19

0.25

Question 20

r of cousins

Answer 20

0.125

Question 21

r of aunts or uncles to their neice or nephew

Answer 21

0.25

Question 22

direct fitness

Answer 22

fitness gained through personal reproduction

Question 23

indirect fitness

Answer 23

fitness achieved by helping nondescendent kin survive and reproduce

Question 24

inclusive fitness

Answer 24

a sum of an individuals bot direct and indirect fitness. a total measure of an individuals contributions of genes to the next generation generated by both the direct and indirect fitness.

Question 25

kin selecion

Answer 25

a type of natural selection that favors the reproductive success of the relatives an organism helps, even at a cost to the organism’s own fitness.

Question 26

in order for an altruistic trait to be adaptive, the inclusive fitness of an altruistic individual has to be greater than:

Answer 26

it would have been if those individuals had tried to reproduce personally.

Question 27

Hamilton’s rule:

Answer 27

rB>C
r= relatedness
B= benefit
C= cost

Question 28

explain brood parasite birds in terms of why they are selfish using hamiltons rule

Answer 28

We expect selfishness in brood parasites because there are no fitness benefits to their sbilings/recipients because there are no degrees of relatedness.

Therefore, altruistic behavior is more likely across closely related relatives.

Question 29

_____ selection encompasses both kin/individual and group selection

Answer 29

MUTLILEVEL SELECTION.

some people didn’t fully agree with kin selection because they thought there were some situatoins in which group seelction could still apply. Multilevel selection explain these “exemptions,’ such as the fact that insect colony members benefit when there are a more altruistic members of the group (group selection tendency), but also accounts for relatedness playing a factor in how altruistic someone is.

Question 30

What is multilevel selection

Answer 30

colonies with more self-sacrificing individuals will be favored by group selection if groups with more altruists OUTCOMPOETE RIVAL GROUPS AND CONTRIBUTE MORE GENES to the next generation.

-encompases both individual and group-level selection. Ie, selection may occur simulatneously at the level of the group AND the level of the individual: the outcome will depend upon the strength of selection at the different levels.

Multi-level selection can occur in the level of species, groups within species or individuals. There may often be conflcit within genes in an individual itself.

Question 31

haplodiploidy

Answer 31

a SEX-DETERMINATION SYSTEM in which males are haploid and females are diploid.

Question 32

explain haplodiploidy in hymenoptera wasps

Answer 32

males are haploid and possess only one set of chromosomes because of parthenogenesis (development from an unfertilized egg)

females are diploid, developing from fertilized eggs.

Question 33

in haplodiploidy species, what happens to the degree of relatedness of the offspring relative to each parent?

Answer 33

because males are haploid, all their sperm is GENETICALLY IDENTICAL.

in a female , all the sperm she receives will have the same set of genes: her daughters will carry identical sets of paternal genes (100% of dad), but will share only 50% of maternal genes. Therefore, daughters are 50% related to their father and 25% related to their mother, for a total of 0.75.

Therefore, sisters are more related to each other (0.75) than they are to their mother.

Question 34

how does haplodiploidy set the stage for altruism

Answer 34

sisters are related to each other by 0.75, rather than 0.5.

Question 35

in haplodiploidy species, what the degree of relatedness between sisters? brothers and sisters? mothers and daughters?

Answer 35

Sisters share UP TO 75% of their genes
Mothers and daughters share 50% of their genes
Brothers and sisters share 25% of their genes

Question 36

haplodiploidy hypothesis

Answer 36

the relatively higher relatedness of full sisters in haplodiploid populations promotes altruism among siblings, and, consequently, the evolution of eusociality.

Question 37

according to the haplodiploidy hypothesis of eusociality, female worker hymnoptera should help which siblings?

Answer 37

female workers in ants should help their reproductively competant SISTERS and not brothers because they are up to 0.75 related to females, but only 0.25 to their brothers.

a worker bias in favor of sisters would also bring workers into conflict with their mothers, because mothers (queens) are equally related to sons and daughters.

Question 38

Explain the works of bob trivers and hope hare on haplodiploidy

Answer 38

they argued that because sisters are three times more closely related to another than they are to their brothers, wasps should invest three times as much in their sisters than their brothers.

the combined wieght of all the adult females (a measure of the total resources devoted to the production of females) should be three times as much as the combined wieight of all the adult male reproductives.

They noted that workers maintain some level of control over offspring production. If queens had full control, you’d expect a 1;1 ratio because they are genetically related to their sons just as much as to their daughters.

Question 39

two problems to the haplodiploidy hypothesis

Answer 39

1) it doesn’t explain all eusociality- ex/ termites are diploid
2) haplodiploidy works best with monogamy; but many eusocial hymenoptera are polyandrous, lowering relatedness among workers.

Question 40

what is the monogamy hypothesis?

Answer 40

the idea that lifetime monogamy ensures that siblings are highly related, making it evolutionarily adaptive to be an obligately sterile worker, and ultimately making eusociality able to evolve.

Question 41

most eusocial insects are ___ ___. Why is there no incentive for worker insects to go start their own colony?

Answer 41

most eusocial insects are FAMILY GROUPS. If the sterile workers of one family are helping in ways that benefit the entire colony, the fact that their reproducing relatives are present means that sterile individuals CAN GAIN FITNESS benefits from the enhanced output of reproducing relatives

there is no incentive for worker insects to go start their own colony because they must survive to reproduce. There is no incentive for worker insects to go out and start their own colony if they are gaining INDIRECT FITNESS ADVANTAGES from helping their siblings survive to reproduce.

Question 42

T/f: in the case of hymenoptera, polyandry evolved from monogamy

Answer 42

true. all these groups of wasps and ants started off as monogamous. Therefore, monogamy is linked to eusocial behavior.

Question 43

a defining characteristic of eusocial societies is a ______ ___ ___ ___

Answer 43

reproductive division of labour, or the PRESENCE OF CASTE SYSTEMS

Question 44

in all eusocial species, there is a ___ ____.

Answer 44

REPRODUCTIVE CASTE: a queen or queens, and sometimes a king, and the rest tend to be of the worker caste who forage, take care of young, and perform other colony work.

Question 45

Castes in harvester ants

Answer 45

there is a large queen, a major worker, a minor worker.

some other castes have soldier castes

Question 46

explain worker policing in eusocial insects.

Answer 46

workers and the queen monitor the reproductive behavior of others. Being sterile might actually not be voluntary.. Eggs laid by individuals other than the queen will usually be eaten by other colony members.

Question 47

what is reproductive conflict

Answer 47

encompasses not only conflict over which individuals get to breed, but also the battle over the resources that individuals need to breed.

Question 48

outline reproductive conflict seen in ant colonies.

Answer 48

individuals that are about to reproduce are detected by colony-mates and physically prevented from doing anything for hours or days.

The queen smears the ant in the center with her sting. Three workers grasp the would-be reproductive ant from moving.
After holding her captive for 3 or 4 days, a worker may turn her prisoner over to another worker to continue imprisonment.

Question 49

the percentage of reproducing workers in the nests of social wasps ____ as the effectiveness with which their fellow workers destroy their eggs increasese.

Answer 49

the percentage of reproducing workers in the nests of social wasps DECREASES as the effectiveness with which their fellow workers destroy their eggs increases.

Question 50

if worker policing is responsible for reducing the number of workers’ songs, then in cases with low number of worker sons, the policing workers are:

Answer 50

the policing workers are MORE CLOSELY RELATED TO THE QUEENS SONS THAN OTHER WORKERS SONs.

Question 51

the greater the difference in the relatedness of worker’s and queens sons, the greater the proportion of males that are produced by:

Answer 51

workers. ex/ the queen would be “more okay” with workers reproducing if they shared more genes with the potential offspring.

Question 52

kin selection vs group selection

Answer 52

kin selection theory has been used to make testable predictions about the kinds of conflicts likely to occur in colonies.

group selection is better at explaining altruism than conflict.