Population Ecology: Key Concepts and Growth Models

What is a habitat?

The physical location where the members of a population live.

What is population density?

The number of individuals of a species per unit area or unit volume of a habitat.

What does population distribution describe?

How individuals are scattered through the habitat.

Name the three types of population distributions.

Uniform, clumped, and random.

What are three methods for estimating population size?

Aerial photos, sampling small subsets, and mark-recapture.

What factors increase population size?

Births and migration into the population.

What factors decrease population size?

Deaths and migration out of the population.

How is the birth rate calculated?

By dividing the number of births by the population size.

How is the death rate calculated?

By dividing the number of deaths by the population size.

What is the formula for population growth rate (r)?

r = birth rate (b) - death rate (d).

What does G represent in population ecology?

The growth increment, or the number of individuals added to or lost from a population in one unit of time.

What is the formula for calculating G?

G = rN, where r is the population growth rate and N is the population size.

How is the population size for the next year calculated?

Population size next year = Current population size + G.

What is exponential population growth?

Population growth that occurs when resources are unlimited, typically represented by a J-shaped curve.

What are density-dependent factors?

Factors that limit population growth and depend on the density of the population.

What are density-independent factors?

Factors that limit population growth regardless of population density, such as natural disasters.

If a population of 100 individuals has 60 births and 40 deaths in one month, what is the birth rate?

0.6 (60 births / 100 individuals).

If a population of 100 individuals has 60 births and 40 deaths in one month, what is the death rate?

0.4 (40 deaths / 100 individuals).

If a population has a birth rate of 0.6 and a death rate of 0.4, what is the population growth rate?

0.2 (0.6 - 0.4).

What will be the population size after one year if the growth increment (G) is 20 and the current population size is 100?

120 individuals.

What is the population size after two years if the growth increment (G) is 24 and the population size after the first year is 120?

144 individuals.

How do you calculate the population size at N3 given N2 and G?

N3 = N2 + G.

What happens to population growth if the death rate exceeds the birth rate?

The population size will decrease.

What is the significance of the formula N2 = N1 + G?

It calculates the population size after one year of growth based on the original population size and growth increment.

What is the shape of the curve representing exponential population growth?

J-shaped curve.

What is the shape of the curve representing logistic population growth?

S-shaped (sigmoid) curve.

What is carrying capacity?

The maximum number of individuals of any species that can be indefinitely supported in a given area.

What happens to growth rate (G) as population size (N) approaches carrying capacity (K)?

Growth rate (G) tends to approach zero as N gets closer to K.

What is the formula for calculating population growth (G)?

G = rNt, where r is the intrinsic growth rate and Nt is the current population size.

If N equals K, what is the growth rate (G)?

G equals 0, indicating no population growth.

What is the intrinsic growth rate (r)?

The difference between the birth rate (b) and the death rate (d), expressed as r = b - d.

How do immigration and emigration affect population size?

Immigration increases population size, while emigration decreases it.

What is the expected population size (N2) if N1 = 100, r = 0.05, G = 5, and K = 150?

N2 would be approximately 105.

What is the population growth pattern of the wolves in Yellowstone National Park from 1995 to 2001?

The growth pattern is classified as logistic due to the lack of natural predators and abundant food sources.

What is the predicted population size of wolves at the end of 1998 if 12 wolves were released in 1995?

The predicted population size was approximately 324 wolves.

What happens to the elk population when it reaches carrying capacity?

The birth rate equals the death rate, stabilizing the population.

What is the growth pattern of the goldfish population introduced into Round Pond?

The growth is best described as exponential due to rapid reproduction and few natural predators.

What is the carrying capacity of the goldfish population in Round Pond?

The carrying capacity would be close to 10,600 goldfish.

When a population reaches its carrying capacity, what happens to the birth and death rates?

The birth rate equals the death rate (b = d).

What is the effect of a dense population of penguins on their distribution?

They are likely to have a uniform type of distribution due to fierce guarding of nests.

What is the significance of conservation biologists in relation to carrying capacity?

They work to protect or create habitats for endangered species, raising the carrying capacity for those species.

How does competition affect population dynamics?

Increased competition for resources can lead to decreased growth rates and increased mortality.

What is the relationship between population density and disease spread?

As population density increases, the spread of disease typically accelerates.

What mathematical relationship defines logistic population growth?

Logistic growth can be modeled with the equation G = rN[(K - N) / K].

What does it mean if G is negative?

A negative G indicates that the population is declining.

What is the role of predators in population dynamics?

Predators can regulate prey populations, affecting their growth and survival rates.

What is the impact of habitat destruction on carrying capacity?

Habitat destruction typically lowers the carrying capacity for species living in that habitat.

What factors can lead to a population crash?

Overpopulation, resource depletion, and increased disease can lead to a population crash.

What is the significance of the S-shaped curve in logistic growth?

It illustrates how population growth slows as it approaches carrying capacity.

What is the effect of abundant resources on population growth?

Abundant resources can lead to rapid population growth until carrying capacity is reached.