Biology 102: Chapter 53

Suppose that scientists also studied a second population of Belding's ground squirrels from a different habitat. Life table data for the first three years of this hypothetical population are shown below. (Note that the table is not completely filled in because you will be calculating some of these values.) Age (years) Number Alive at Start of Year Proportion Alive at Start of Year Death Rate Average Number of Female Offspring 0-1 80 1.000 0.00 1-2 64 ? 1.20 2-3 40 2.40 Which equation determines the proportion of ground squirrels alive at the start of year 1-2? (This value is marked with a "?" in the table.)

64/80 = 0.800

Determine whether the actions described will increase K, decrease K, or not affect K.

K increases - an abandoned building creates more nesting areas - a main competitor for food is eliminated, increasing food availability K decreases - a parking lot is built, shrinking the habitat - wetlands are drained, decreasing the amount of available water - a species with the same food requirements is introduced No Effect on K - offspring live longer

Let's compare the life tables of the two Belding's ground squirrel populations. This is the life table for the first population, as shown in the figure walkthrough: Age (years) Number Alive at Start of Year Proportion Alive at Start of Year Death Rate Average Number of Female Offspring 0-1 653 1.000 0.614 0.00 1-2 252 0.386 0.496 1.07 2-3 127 0.197 0.472 1.87 This is the life table for the second population: Age (years) Number Alive at Start of Year Proportion Alive at Start of Year Death Rate Average Number of Female Offspring 0-1 80 1.000 0.200 0.00 1-2 64 0.800 0.375 1.20 2-3 40 0.500 0.450 2.40 Which statement regarding the two populations of Belding's ground squirrels is correct?

The second population had a higher proportion alive at the start of year 1-2.

Which of the following conditions favors "big-bang" reproduction?

low rates of offspring survival

The rate of human population growth is increasing.

not supported

In the models that describe population growth, r stands for _____

per capita population growth rate

During the 20th century, the human population increased from less than 2 billion to more than 6 billion.

supported

From 1500 to 2010, the human population approximately followed the exponential growth model.

supported

Total population size is projected to increase through the middle of the 21st century

supported

To determine the density of a rabbit population, you would need to know the number of rabbits and _____

the size of the area in which they live

Which decade had, or is projected to have, the highest annual population increase?

1980-1990

Here is the same life table again. Age (years) Number Alive at Start of Year Proportion Alive at Start of Year Death Rate Average Number of Female Offspring 0-1 80 1.000 ? 0.00 1-2 64 0.800 1.20 2-3 40 2.40 Which equation determines the death rate in year 0-1? (This value is marked with a "?" in the table.)

(80-64)/80 = 0.200

According to this graph, the world population doubled between _______.

1930 and 1975

What is represented by the distance between two vertical white gridlines on this graph?

A time span of 50 years

Which of the following is regarded as a density-independent factor in the growth of natural populations?

flooding

A population of animals in a specific environment with a K of 2500 has an rmax of 1.0 per individual per year and exhibits logistic growth as follows: dN/dt=rmaxN(K−N)/K Arrange the following population sizes in order of decreasing growth.

Fastest Growth N= 1250 N= 1500 and 1000 N= 750 N= 500 N= 2500

What is represented by the vertical blue bars on this graph?

The number of people added to the population annually in each decade

The number of individuals that a particular habitat can support with no degradation of that habitat is called _____

carrying capacity

In wild populations, individuals most often show a _____ pattern of dispersion.

clumped