Deck 12: After Conception: the Evolution of Life History and Parental Care

Question 1

In laboratory experiments, short-lived nematodes outcompete long-lived nematodes. This provides evidence that

A) natural selection does not favor long life for long life's sake.
B) longevity-extending mutations lower early reproductive fitness.
C) natural selection favors longer lived organisms.
D) a and b
E) a, b, and c

Answer 1

D

Question 2

Which living organism experiences menopause?

A) chimpanzee
B) killer whale
C) Drosophila fly
D) none of the above

Answer 2

B

Question 3

Which of the following is a critical assumption of the Trivers-Willard hypothesis?

A) Offspring condition depends on the mother's physiological condition.
B) Paternity in the population is skewed heavily toward males in best condition.
C) Most females in the population mate.
D) all of the above
E) none of the above

Answer 3

A

Question 4

Why might NOT a limited diet increase longevity?

A) An unlimited diet leads to obesity.
B) A limited diet may trigger a stress response that repairs damaged cells.
C) A limited diet increases the reproductive capacity of an individual.
D) An unlimited diet leads to diabetes.

Question 5

In species where there is an unbiased operational sex ratio, you would most likely see

A) both males and females cooperating in the care of young.
B) strong sexual selection.
C) more females ready to breed compared to males.
D) females fulfilling the majority of parental care.

Question 6

Based on the outcome of previous experiments, if you moved guppies from predator-free streams to predator-rich streams for many generations, which of the following changes is most likely to occur?

A) Male fish would mature at larger body size.
B) Females would produce more offspring.
C) Embryos would be larger.
D) all of the above

Question 7

What is menopause for human women?

A) their remarkably long life span
B) the unnaturally early onset of puberty
C) the loss of fertility later in life
D) the state of being born infertile

Question 8

Why might it be beneficial for a parent to adjust their number of offspring?

A) because with the uncertainty of reproduction, a flexible response may be more adaptive
B) because daughters always increase the reproductive success of a parent
C) the fewer offspring, the more a parent will increase their own fitness (ability to survive)
D) all of the above

Question 9

Some evolutionary biologists have argued that menopause is adaptive based on the mother hypothesis. Which statement(s) below help(s) form the logical basis of their argument?

A) The risks of childbearing increase with age.
B) Older mothers are unlikely to survive until offspring reach independence.
C) Remaining fertile detracts from investment in current offspring.
D) all of the above

Question 10

How do Igf2 and Igf2r affect parental fitness?

A) Igf2 is a growth-promoting gene, which may reduce a mother's fitness.
B) Igf2 is a growth-inhibiting gene, which may increase a mother's fitness.
C) Igf2r is a growth-inhibiting gene, which may increase a father's fitness.
D) Igf2r is a growth-promoting gene, which may increase a mother's fitness.

Question 11

If extrinsic mortality is high,

A) selection will act more strongly against mutations that negatively affect organisms late in life than those that do so early in life.
B) selection will act equally strongly on mutations that negatively affect organisms early in life and late in life.
C) organisms are likely to age more rapidly than if extrinsic mortality were low.
D) a and c
E) b and c

Question 12

What did surgical removal of ovaries in brown anolis lizards demonstrate?

A) Females without ovaries grow faster because they have free resources to invest in growth.
B) Control females (with ovaries) used resources to invest in eggs.
C) There is a trade-off between growth and reproduction in brown anolis females.
D) a and b only
E) a, b, and c

Question 13

Male and female penduline tits cooperate to build nests and bring food to their young, but exhibit conflict over who provides care the longest. This is an example of

A) parent-offspring conflict.
B) parental conflict.
C) sexual conflict.
D) a and b
E) b and c

Question 14

Which of the following is true regarding senescence?

A) Animals may vary in longevity, but the aging processes are similar.
B) There is minimal variance in either longevity or the process of aging among animals.
C) The aging process differs dramatically among animal species.
D) Aging must be explained by different evolutionary forces among different species.

Question 15

Which of the following support(s) the hypothesis that miscarriages may be favored by natural selection for embryos that are unlikely to survive?

A) In humans, miscarriages can reduce nine months of investment to a month or less for embryos unlikely to survive.
B) Many human embryos with abnormal chromosome numbers result in miscarriages in the first trimester.
C) Most embryos with normal chromosome numbers continue to term.
D) all of the above

Question 16

Genomic imprinting

A) occurs when certain genes are silenced in egg or sperm.
B) results in offspring that express both the maternal and paternal copies of a gene.
C) occurs only in humans.
D) is when certain genes are silenced via transcription factors.

Question 17

Which of the following examples does not support the Trivers-Willard hypothesis?

A) Gravid females of certain hymenoptera species can directly manipulate the sex of their offspring by fertilizing, or not, eggs before laying.
B) Male sand gobies devour some offspring when density increases.
C) Female Seychelles warblers adjust the balance of male and female chicks in broods.
D) The bluestreak cleaner wrasse begins life as a female, but switches its sex to male when the benefits of being male outweigh those of being female.

Question 18

Parental conflict continues at the molecular level via

A) senescence.
B) menopause.
C) genomic imprinting.
D) Parental conflict can only occur at an organismal level.

Question 19

Which statement helps explain why male pipefishes produce very few sperm?

A) Male fitness is limited mostly by the number of eggs they can fertilize.
B) Male fitness is limited mostly by the number of eggs they can care for.
C) Male fitness is limited mostly by the number of females available for mating.
D) none of the above

Question 20

How does the mother hypothesis explain menopause?

A) Women need to allocate resources toward the demanding needs of offspring and are more able to do so without more children.
B) Women who become pregnant at a later age face a threat to reproductive success by potential loss of current offspring.
C) Women who become pregnant at a later age face the threat of death during childbirth.
D) all of the above

Question 21

The ideal organism would be reproductively mature at birth, have high fecundity, reproduce continually, and live forever. Please explain why such an organism does not exist.

Question 22

Imagine that you collect data from many different species that vary in their rate of extrinsic mortality. Based on predictions from evolutionary theory, draw an expected plot with extrinsic mortality on the x axis and rate of senescence on the y axis.

Question 23

Which of the following is/are part of the life history of an organism?

A) age at first reproduction
B) duration and schedule of reproduction
C) number of offspring per reproductive episode
D) all of the above

Question 24

Evidence suggests that male pipefishes may be able to adjust investment in offspring depending on the size of the female. How would the probability of remating influence the optimal investment strategy by males?

Question 25

The Kakapo is a critically endangered flightless parrot from New Zealand. A number of efforts have been employed in order to stave off its extinction. Early on, the parrots were given supplemental food in order to ensure that they remained healthy. This had a positive impact on survival, but unfortunately the population remained at risk, in part because sex ratios were highly male biased. Based on research on sex ratios in other species, offer a hypothesis as to why sex ratios were male biased.

Question 26

You are studying sex ratios in Seychelles warblers. A drought results in very low resources. Explain how this is likely to affect the population sex ratio and why it would benefit the female to adjust the sex ratio this way.

Question 27

David Haig has proposed that genomic imprinting in the placenta is a signature of conflict between the parents over investment in offspring. Why would fathers benefit from a strategy that reduces the fitness of the mother of their offspring?

Question 28

In the Eurasian penduline tit, what are the costs and benefits for males of leaving the female?

Question 29

What does the following figure on primate longevity and fertility reveal?

A) Humans tend to live years after their last live birth.
B) Monkeys and apes do not live long after their last live birth.
C) Humans go through menopause because they live years after their last live birth.
D) a and b
E) a, b, and c

Question 30

You discover a new gene expressed in the placenta. You find that this gene is responsible for diverting more nutrients to the developing fetus. Based on the conflict hypothesis for imprinting, it is most likely that

A) the father's copy is turned on; the mother's copy is turned off.
B) the mother's copy is turned on; the father's copy is turned off.
C) both the mother's and the father's copies are turned on.
D) both the mother's and the father's copies are turned off.

Question 31

Which of the following is not an example of the deleterious effects of aging?

A) Cells accumulate malformed proteins.
B) Rates of noninfectious disease increase.
C) Immune system function decreases.
D) Fertility increases.

Question 32

In wattled jacanas,

A) there is a female-biased operational sex ratio.
B) males fight over access to females.
C) females recycle faster than males because they abandon eggs while males take on paternal care.
D) a and b
E) a and c

Question 33

Tasmanian devils are experiencing a massive population crash due, in part, to the emergence of a contagious cancer called devil facial tumor disease. The disease has significantly altered the age structure of populations, with far fewer older individuals in populations affected by the disease. Prior to the disease, devils typically reproduced seasonally starting in their second year. What effect would this change likely have on reproductive schedules in devil populations?

Question 34

The evolutionary conflict of interest over the optimal strategy for parental care is

A) parent-offspring conflict.
B) parental conflict.
C) offspring-offspring conflict.
D) sexual conflict.

Question 35

Would more parental conflict likely occur in species with monogamous or polygamous mating systems? Explain your answer.

Question 36

You discover a new imprinted gene in the placenta. The father's copy of the gene is turned on, and the mother's copy is turned off. Describe a process for determining what effect this gene has on the developing fetus.

Question 37

The evolutionary conflict of interest between siblings competing for parental care is

A) parent-offspring conflict.
B) parental conflict.
C) offspring-offspring conflict.
D) sexual conflict.

Question 38

The grandmother hypothesis

A) explains prolonged post-reproductive life span in women.
B) explains that helping grandchildren ultimately raises fitness.
C) explains why menopause occurs at the point it does in women's lifespans.
D) a and b
E) b and c

Question 39

Methylation is

A) short-term modification of gene expression.
B) long-term modification of gene expression.
C) the addition of methane groups to an enhancer.
D) the uncoiling of DNA, making transcription easier.

Question 40

What evidence suggests that male pipefishes adjust the amount of their investment in offspring depending on the size of the female?

Question 41

Compare the mother hypothesis and grandmother hypotheses as explanations of menopause and longevity of females.

Question 42

Researchers have demonstrated that the maximum life span of Drosophila melanogaster can be increased dramatically through artificial selection. This clearly demonstrates that genetic variation for increased longevity exists in
D. melanogaster populations. Why have flies likely not evolved longer life spans?

Question 43

Why is the placenta a structure that is particularly suited as an arena for interfamilial conflicts to play out?