Question 1

Explain two significant ways in which environmental productivity and stability can influence the number of offspring produced and their probability of survival.

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Question 2

Yucca plants are mostly iteroparous, but some can be semelparous. Based on the information in Figure 8.9, semelparous yuccas have a higher percentage of seed germination, which suggests high fitness. Why, then, are most yucca varieties iteroparous?

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The answer of Yucca plants are mostly iteroparous, but some...

Question 3

A mature female sockeye salmon swims up to 5,000 km from her Pacific Ocean feeding ground to the mouth of a coastal river in British Columbia and then another 1,000 km upstream to her spawning ground. Once there, she lays thousands of eggs in her single reproductive event and promptly dies. The salmon's reproductive life history is

Accepted Answer

Semelparous refers to organisms that reproduce just once and then die, which is the case with the female sockeye salmon.

Question 4

According to the figure, what are the implications of producing five versus eight eggs? Which option should be favored by natural selection?

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Question 5

Which variable best summarizes the response to increased predation mortality for adults and suggests that putting more energy into reproduction provides an improved fitness benefit?

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Question 6

What type of reproduction will be favored if adult plant survival is low because of a disturbance such as fire?

Accepted Answer

Semelparity, also known as "big bang" reproduction, involves a single reproductive episode in an organism's lifetime, which would be advantageous if adult plant survival is low due to a disturbance such as fire. The plant would allocate all its resources into one big reproductive event before dying, rather than trying to survive and reproduce multiple times, which may not be feasible in a disturbed environment.

Question 7

How would fecundity and age at maturity be influenced by adult and juvenile survival rates?

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Question 8

The number of chicks fledged in a brood may not be independent of the number of eggs produced. How might researchers test these variables independently to determine whether there is a relationship between them?

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The answer of The number of chicks fledged in a...

Question 9

Red foxes mature after their first year of life and may live for 5 to 10 years. Foxes often reproduce many times over their life. The term to describe this aspect of their life history is

Accepted Answer

The term that describes the ability of an animal to reproduce multiple times over its life is iteroparity. Red foxes fit this description as they often reproduce many times over their 5 to 10 year lifespan. The term opportunistic refers to a species that takes advantage of whatever resources are available at the time, while precocious refers to animals that are capable of reproducing at a young age. Semelparity, on the other hand, refers to animals that reproduce only once in their lifetime and then die.

Question 10

In human females the increased prevalence of birth defects in offspring and of infertility after 30 years of age is one indication of

Accepted Answer

The increased prevalence of birth defects in offspring and of infertility after 30 years of age in human females is an indication of senescence, the gradual deterioration of physiological function with age. This is not related to iteroparity or semelparity (reproductive strategies that relate to how many times an organism reproduces in its lifetime), middle age (a general stage of life between young adulthood and old age), or reproductive failure (which could have a variety of causes beyond just senescence).

Question 11

A gradual decrease in fecundity and increase in the probability of mortality is known as

Accepted Answer

Senescence is the gradual decline in physical functioning, reproductive performance, and an increase in the probability of mortality as an organism ages. Logistic growth is a type of population growth that involves a sigmoid-shaped curve as a population approaches its carrying capacity. Acclimation is the process of an organism adjusting to a change in its environment through physiological or behavioral changes. Semelparity refers to a reproductive strategy in which an organism reproduces only once in its lifetime and then dies.

Question 12

We might expect natural selection to favor organisms that produce more offspring. Why is this not the case for species with a high degree of parental care?

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The answer of We might expect natural selection to favor...

Question 13

If maintaining high survival and reproduction would increase an individual's fitness at any age, what is the most likely reason these traits decline with age in humans?

Accepted Answer

DNA damage accumulates over time due to errors in replication, environmental factors, and the body's inability to perfectly repair all damage. This accumulation can lead to the decline in survival and reproduction traits as individuals age.

Question 14

Use the information in the figure to explain whether the fitness of the parent increases with more eggs produced and why.

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Question 15

Compare the relative influence of determinate and indeterminate growth patterns on natural selection for adult size.

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Question 16

Bet hedging (spreading reproduction over both good and bad years) has been proposed as an advantage to

Accepted Answer

Bet hedging, or spreading reproduction over both good and bad years, is an advantage of iteroparity. Iteroparous species can reproduce multiple times over their lifespan, allowing them to take advantage of favorable conditions in different years, whereas semelparous species reproduce only once and then die, which does not allow for spreading reproductive efforts over time.

Question 17

Tropical songbirds tend to lay fewer eggs in each clutch than birds nesting at higher latitudes. David Lack of Oxford University first placed this observation in a life history context. To what relation did Lack attribute this pattern?

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Question 18

Which panel best illustrates the most direct effect of predation?

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Question 19

What is the reproduction pattern of most insects?

Accepted Answer

Most insects exhibit semelparity, meaning they reproduce only once during their lifetime.

Question 20

For seed-producing trees, what conditions might favor production of few relatively large seeds? What conditions might favor production of many relatively small seeds?

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The answer of For seed-producing trees, what conditions might favor...

Quiz 8: Life Histories