Chapter 12 Ecology The Economy of Nature

Question 1

A population’s maximum per capita growth rate is called the _____ growth rate.

Answer 1

intrinsic

Question 2

A graphical relationship that shows how decreases in population density over time lead to increases in the mass of each individual in the population is referred to as _____.

Answer 2

a self-thinning curve

Question 3

A type III survivorship curve depicts a population with _____ mortality early in life and _____ survival later in life.

Answer 3

high; high

Question 4

If a population of bears, which breed only once per year in the spring, grows from 100 to 120 individuals over a 5-year period, then _____.

Answer 4

λ > 1

Question 5

In the logistic growth model, when the number of individuals in a population is small relative to the carrying capacity, the rate at which the population grows is _____.

Answer 5

exponential

Question 6

For life tables, _____ is operationally defined as the number of female offspring produced per reproductive female.

Answer 6

fecundity

Question 7

To estimate how populations grow over time under ideal conditions, we use the _____ growth model for species that reproduce throughout the year and the _____ growth model for species that have limited breeding seasons. To depict the slowing growth rate of populations as the carrying capacity is approached, we use the _____ growth model.

Answer 7

exponential; geometric; logistic

Question 8

A population of emperor penguins in Antarctica consists of 214 individuals and has an intrinsic annual growth rate of 0.07. Recent work by scientists shows that the waters where the penguins live are productive enough to sustain a maximum of 287 individuals. On a per capita basis, what is the penguin population’s current annual rate of increase?

Answer 8

0.02 individuals

Question 9

Individuals in populations with type I survivorship curves typically _____.

Answer 9

exhibit a high degree of parental care for offspring

Question 10

In the exponential growth model, a population increases faster over time because _____.

Answer 10

the number of reproductive individuals in a population increases over time

Question 11

For the past two decades a scientist has been studying the population dynamics of a prairie dog town. Over the course of her study, the scientist calculated the population growth rate for different time intervals. She also determined that the carrying capacity for the town is 252 individuals. Using the logistic growth model, and assuming the intrinsic growth rate stayed the same throughout the study, at what population size would the scientist have found the fastest rate of growth?

Answer 11

135

Question 12

You began studying the population growth of an invasive aquatic weed on August 23, 2005, when the population contained 350 individuals. You monitored the population’s abundance every year from 2005 through 2010, when the population had 1,550 individuals. On August 23, 2010, what was the approximate instantaneous rate of change of the invasive weed’s population size?

Answer 12

dN/dt = 240 individuals per year

Question 13

After constructing a life table for a red fox population, you determine the population’s net reproductive rate (R0) is 3.2 and the generation time (T) is 1.3 years. Therefore, you approximate the intrinsic rate of increase as: λa = _____ and rα = _____.

Answer 13

2.45; 0.89

Question 14

On a recent trip to the Amazon rainforest, you discover a new insect species. You perform some basic life history studies and discover three characteristics of this species: (1) This insect produces a large number of small-bodied young, which have low survivorship. (2) Individuals that survive their first year have very high survivorship for the next 2 years. (3) After individuals reach age 3, their survivorship drops significantly each year until they are 5, after which no individuals survive. This new insect species has a type _____ early-life survivorship curve, a type _____ midlife survivorship curve, and a type _____ late-life survivorship curve.

Answer 14

III; I; I

Question 15

You are hired by a farmer to solve her problem with groundhogs eating her crops. You look up groundhog life history and find that these animals mate and produce young only in the spring. You know that to address the farmer’s problem with the groundhogs you must first understand how large the population is and how fast it is growing. You estimate that the current size of the groundhog population is 32 individuals and that the annual rate of growth is 1.73. What do you estimate the change in population size per year will be after 2 more years?

Answer 15

63 individuals

Question 16

According to the logistic growth model, when the term inside the parentheses, (1 - N/K), approaches 1, it means _____.

Answer 16

the number of individuals in the population is small relative to the carrying capacity

Question 17

An island can support a population of 1,340 birds with an intrinsic annual growth rate of 0.23. If this bird population is at its inflection point when the bird population size is plotted against time, what is the population’s current growth rate per year?

Answer 17

77

Question 18

Polar bears are considered vulnerable to extinction because of habitat loss caused by melting sea ice. Which technique for predicting how polar bear populations will change in abundance over time is MOST useful for scientists wishing to conserve polar bears?

Answer 18

generating a static life table by compiling survival and fecundity data of individuals of all ages during a single time interval

Question 19

In the geometric growth model, what does a λ value of 0.97 mean?

Answer 19

The population has decreased from one year to the next because the number of deaths has exceeded the number of births.