Chapter 53 - Population Ecology

A population of 3000 starfish has a yearly per capita population growth rate of 0.012. A year from now, how big will the population be? Assume that the population grows exponentially according to the equation

3036 r = 0.012, N = 3000 3000 × 0.012 = 3036

A population of 1000 monkeys has a yearly birth rate of 80 young, and a yearly death rate of 90 individuals. In one year, the population will be...

990 monkeys 1000 to start+80 born-90 dead=990 individuals in one year

What is the carrying capacity for this population of whooping cranes?

>325

Compared to exponential growth, what happens as the population size grows and approaches nears carrying capacity? A) population growth rate speeds up B) population growth rate slows down C) population growth rate stays the same

B) population growth rate slows down

An ecosystem has a carrying capacity of 1,000 individuals for a given species, and 2,000 individuals of that species are present. The population... A) size will slowly increase. B) size will decrease. C) will show a clumped dispersion pattern. D) size will remain at equilibrium.

B) size will decrease.

Which population should display the highest growth rate? A) One with a high birth rate and a high death rate B) One with a low birth rate and a low death rate C) One with a high birth rate and a low death rate D) One with a low birth rate and a high death rate

C) One with a high birth rate and a low death rate

In the logistic population growth model, A) new individuals are added most rapidly to the population when N is very big B) the population doubles every year C) population growth rate increases when N approaches K D) population growth rate is slow when N is small and when N is close to carrying capacity

D) population growth rate is slow when N is small and when N is close to carrying capacity

Under what conditions would a population grow slower than predicted by exponential growth? A) Low food resources B) Limited refuges C) Limited nesting sites D) Limited nutrients E) All of the above

E) All of the above

A population of 2000 starfish has a yearly per capita population growth rate of 0.012. By next year, how do you expect population size to have changed? Assume that the population grows exponentially according to the equation

It will increase by 24 starfish r = 0.012, N = 2000 2000 × 0.012 = 24

A population of flamingoes in Florida grows according to a logistic model, with r = 0.17 and K = 10,000. Which of the following statements are correct? Check all that apply.

dN/dt is lower at N=200 than it is at N=5000 dN/dt is lower at N=9000 than it is at N=5000 dN/dt will be negative if N = 12,000

exponential population growth

growth of a population in an ideal, unlimited environment, represented by a J-shaped curve when population size is plotted over time

A population of snails has an annual per capita birth rate of 0.055 and an annual per capita death rate of 0.015. Calculate an estimate of the change in population size over one year, for a given starting population of 1,000 individuals. Assume that the population grows exponentially according to the equation

increases by 40 individuals r = birth rate - death rate, so 0.055 - 0.015 = 0.04. N is 1000 1000 × 0.04 = 40

Which species can have a more rapid population growth?

mouse

What is the earth's carrying capacity for humans?

not too sure

logistic population growth

population growth that levels off as population size approaches carrying capacity

Based on the following equation of population growth: 𝑑𝑁𝑑𝑡=𝑟𝑁dNdt=rN a population will be stable over time when...

r=0

density independent

referring to any characteristic that is not affected by population density

density-dependent

referring to any characteristic that varies with population density

ecological footprint

the aggregate land and water area required by a person, city or nation to produce all of the resources it consumes and to absorb all of the waste it generates

carrying capacity

the maximum population size that can be supported by the available resources, symbolized as k

For an albatross population to be stable, how many offspring should females have on average?

~2 offspring

Bacteria reproduce by binary fission (one cell becomes two cells). Imagine that the generation time for Lactobacillus acidophilus is one hour. You start a culture of L. acidophilus at noon with 100 bacteria, in a large petri dish with a great culture medium (i.e. resources are not limiting). What is the current R0 for L. acidophilus? (assume that no bacteria die)

2

In a stable frog population, the average female produces 6,000 eggs during her lifetime and an average of 300 tadpoles hatch from these eggs. How many of these tadpoles will, on average, survive to reproduce?

2

A population of 1000 monkeys has a yearly birth rate of 80 young, and a yearly death rate of 90 individuals. The yearly per capita population growth rate is...

-0.01 b = 80/1000 = 0.08 d = 90/1000 = 0.09 r = b - d → 0.08 - 0.09 = -0.01

The net reproductive rate most directly helps predict future population size in...

1 generation

A population of snails is located in a lake that has a carrying capacity of 20,000 snails. The intrinsic capacity for increase for these snails is 0.15 and the current population is 12,000. In a year, how big do you expect the snail population to be?

12,720

Bacteria reproduce by binary fission (one cell becomes two cells). Imagine that the generation time for Lactobacillus acidophilus is one hour. You start a culture of L. acidophilus at noon with 100 bacteria, in a large petri dish with a great culture medium (i.e. resources are not limiting). Four generations later (at 4pm), how many bacteria are there?

1600

A K-selected species is likely to follow which type of life curve?

A (Type I - most individuals die late in life)

For populations that grow exponentially (𝑑𝑁𝑑𝑡=𝑟𝑁dNdt=rN): which of the following populations will experience the fastest population growth rate?

A population of 1000 rabbits that has a yearly death rate of 0.01 and a yearly birth rate of 0.11 Given that all these populations have the same initial size, the population with the fastest per capita growth rate (r) will have the fastest population growth. For rabbits, r=0.1; for wolves, r=0.05; for elephants, r=0.01 and for blue whales, r=0. Therefore the rabbit population will increase the fastest

Which of the following statements is correct about the graph of exponential population growth shown here? A) Over time, the population size gets bigger and the rate of population growth becomes faster. B) Over time, the population size gets bigger and the rate of population growth becomes slower. C) Over time, the population size gets smaller and the rate of population growth becomes faster. D) Over time, the population size gets smaller and the rate of population growth becomes slower.

A) Over time, the population size gets bigger and the rate of population growth becomes faster.

Population ecologists are primarily interested in A) understanding how biotic and abiotic factors influence the size of groups of interbreeding individuals. B) how humans affect the size of wild populations of organisms. C) studying interactions among populations of organisms that inhabit the same area. D) how gene pools of populations change over time

A) understanding how biotic and abiotic factors influence the size of groups of interbreeding individuals.

The carrying capacity for the Puerto Rican lizard cuckoo is limited by the amount of lizard prey available. Typically carrying capacity is 30,000 individuals. Over a 10-year period, there is an increase in the population of anole lizards, their favorite prey. Over this period, the Puerto Rico's carrying capacity for Puerto Rican lizard cuckoo will... A) Be constant B) Increase C) Decrease D) Be likely to change, but unclear in which direction

B) Increase

In logistic growth, which of these is likely to occur as population density increases A) Per capita birth rate increases B) Per capita birth rate decreases C) Per capita death rate decreases D) Carrying capacity increases

B) Per capita birth rate decreases

A population of 18 wolves is declining. Which of the following could be true? A) R0 = -0.1 and r = -0.1 B) R0 = 0.9 and r = -0.035 C) R0 = -0.047 and r = -0.8 D) R0 = 0.8 and r = 0.75 E) R0 = 1.8 and r = -0.078

B) R0 = 0.9 and r = -0.035

net reproductive rate

expected number of offspring of a female during her lifetime

Which of the following is an r-selected animal?

fish

Which of the following cause of mortality is most likely to be density-independent? A) Competition for food B) Disease C) Fire

C) Fire

per capita growth rate

for some interval, the added number of individuals divided by the initial population size

What does a negative per capita population growth rate tell you about a population? A) The birth rate equals the death rate. B) The population size is increasing instead of decreasing. C) The population size is decreasing instead of increasing.

C) The population size is decreasing instead of increasing.

On your first day as a wildlife biologist for a national park, you are told that yearly changes in the size of the wolf population in the park can be modeled with the following equation, where N is 120 and r is -0.05. 𝑑𝑁𝑑𝑡=𝑟𝑁dNdt=rN You conclude that: A) the population is doubling every year. B) In the next year, one in two wolves will die. C) the population is declining, and you expect to have ~114 wolves in the park next year D) the population is growing, and you expect to find ~126 wolves next year.

C) the population is declining, and you expect to have ~114 wolves in the park next year

Which of the following applies to r-selected species?

Early age of first reproduction Short generation time Many offspring per reproductive event Short-lived Little parental care Poor competitor Thrives in shifting environments Fast growing

A population of 18 wolves has a net reproductive rate of 0.95. If this continues for generations, what would you expect to see?

Eventually, the population will go extinct A population will be stable with a R0 of 1, decline with a R0 < 1 and get bigger with an R0 > 1. In this case, the R0 is 0.95 which indicates the population will be smaller in one generation. If the R0 remains stable, the population will keep declining until is extinct.

Bacteria reproduce by binary fission (one cell becomes two cells). Imagine that the generation time for Lactobacillus acidophilus is one hour. You start a culture of L. acidophilus at noon with 100 bacteria, in a large petri dish with a great culture medium (i.e. resources are not limiting). Assuming that the Net Reproductive Rate (R0) does not change for 6 hours, what kind of population growth is occurring?

Exponential

What kind of growth curve has the human population followed?

Exponential

A population of deer in Florida grows according to a logistic model, with r = 0.17 and K = 10,000. At what population size is the per capita population growth rate the highest?

N = 1000 The per capita rate of population growth is highest when the population is small, and (𝐾−𝑁𝐾K−NK) is close to 1. (𝐾−𝑁𝐾K−NK) gets smaller as N gets bigger and it becomes 0 when K = N = 10000.

In logistic growth, population growth will be 0 when...

N=K

For populations that grow exponentially (𝑑𝑁𝑑𝑡=𝑟𝑁dNdt=rN): given a per capita growth rate of 0.1, which of the following populations will have the most rapid population growth?

One with 1000 individuals Since 𝑑𝑁𝑑𝑡=𝑟𝑁dNdt=rN, for a constant r, the rate change in population size will increase with increasing N.

From this graph of the elephant population in Kruger National Park, you can tell that:

The vegetation the elephants eat could support more than 5,000 elephants Even though the population is continually increasing, it doesn't mean that no individuals died. It simply means that more individuals are born than die. This curve shows a classic exponential growth curve, which is what happends when the realized per capita population growth rate is constant and equal to rmax. While the rate of overall population growth (dN/dt) increases over time because the population size is betting bigger, the per capita (i.e. per individual) population growth rate is the same, which means that each female is not having more offspring in 1960 than 1920, it's just that there are more females around having the same number of offspring each. Given that we see the population increase well beyond 5000 without signs of slowing down, it suggests that the carrying capacity (which is based on food availability and many other factors) is greater than 5000.

If the carrying capacity for the North Atlantic cod on the Grand Banks of Newfoundland is 500,000 tons, when do you expect that the rate of population growth would be greatest?

When there are 250,000 tons of cod on the grand banks Overall population growth rate (𝑑𝑁𝑑𝑡dNdt) is greatest when N is at half of K.

population

a group of individuals of the same species that live in the same area and interbreed, producing fertile offspring

r-selected species

a species that has a high intrinsic growth rate, which often leads to population overshoots and die-offs

k-selected species

a species with a low intrinsic growth rate that causes the population to increase slowly until it reaches carrying capacity