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43 Cards in this Set

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  • Back

What is population ecology?

The study of how populations interact in their enviornments

What are the levels ecology can be studied at?

Individuals, populations, communities, ecosystems

What does ecology study on an individual?

Individual organisms

What does ecology study on populations?

Groups of individual organisms that interbreed with each other.

What does ecology study on communities?

Populations of different species that interact with each other within a locale.

What does ecology study on ecosystems?

All living organisms, as well as non-living elements, that interact in a particular area.

Population ecology particularly studies what?

populations patterns of growth and how they are influenced by other species and by enviornmental factors.

Can ecological processes be observed or studied within an individual?

Most cannot.

Why does ecological processes need a group of individuals?

Because they regularly exchange genes in a particular locale.

What can population ecology examine that cannot be studied with an organism but with a population?

Population size.

What are the two things needed to figure out how a population grows or shrinks?

The Per capita growth rate, and the number of individuals in the population at a particular time.

How do you find the Per capita growth rate?

Birth rate - death rate= r

What is the letter that stands for the number of individuals in the population at a certain time?


What is the population growth rate formula?

r×N=Population Growth Rate

500 individuals are in a population. The course of one year 125 offspring are born. 25 out of 500 individuals die during the course of the same year. What is the birth rate, death rate, and how many individuals per individual is in the population per year?

Birth rate is 125/500 or 0.25 births per individual, the death rate is 25/500 or .05 deaths per individual, the growth rate is 0.25-.05 or .20 individuals per individual in the population per year.

How does exponential growth occur?

When each individual produces more than the single offspring necessary to replace itself.

Why does exponential growth not last long in nature?

Because populations cannot grow unchecked forever.

What is a consequence of population density?

Some limitations on a populations growth.

What do organisms experience as population sizes increase?

Reduced food shortages due to competition, Diminished accessibility to places to live and breed due to competition, Increased incidence of parasites and disease, and increased predetation risk.

Why do organisms experience increased incidence of parasites and disease when a population size increases?

It is spread more easily at a high population density.

Why do organisms experience increased predation risk when a population size increases?

Because predator populations grow in response to increased availability of prey.

Ceiling on growth is known as the ________ ________, (_), of the environment.

Carrying Capacity, (K)

What is the population growth formula?

(r × N) × [(K - N)/K]

If [(K - N)/K] is close to 1, is a population growth exponential, close to exponential, or no where near exponential?

Is exponential or close to exponential

What happens if [(K - N)/ K] is close to 0?

The environment is nearly full to capacity, and population growth reduces to almost zero.

What is logistic growth?

Population growth that has stabilized because of limited resources.

What does logistic growth do?

Describes population growth that is gradually reduced as the population nears the environment's carrying capacity.

What is Density-independent Forces?

Factors that strike populations without regard for the size of the population.

What are some density-independent forces?

Fires, floods, and earthquakes

What does Density-independent forces do to a population?

Populations can dramatically decrease in size.

What happens in an enviornment with "bad luck" occurring regularly?

A population can be in a prepetual state of exponential growth with periodic massive mortality events.

Do populations stay about the same size?

Some populations cycle between large and small.

Why does the snowshoe hare and lynx population rise and crash in a 10 year cycle?

1) a growing hare population provides more food for the lynx, which then reproduce at higher rates, 2) Lynx eat too many hares which reduces their food source and causing their own population to crash which enables the hare population to grow.

Populations tend to grow exponentially, but...

This growth is eventually limited.

A populations growth can be limited by density-dependent factors which includes...

The density increasing causing the population to reach the carrying capacity of its environment, and limited resources put a ceiling on growth.

Population growth can be reduced by density-independent factors such as _______ or _____-______ environmental calamities.

Natural, human-caused

Is it simple or easy to utilize natural resources efficiently and sustainably?

Difficulties such as estimating population size and carrying capacity complicate the implementation of such strategies.

What does the vital statistics of the species include?

Age at first reproduction, probabilities of survival and reproduction at each age, litter size and frequency, and longetivity

What are the three variations in life histories?

Big-Bang Reproduction, Fast Intensive Reproductive Investment, Slow Gradual Reproductive Investment

What are the factors to the Big-Bang Reproduction.

Reaches sexual maturity at one year, Mates intensly over a three-week period, Males die shortly after mating period, Females usually die after weaning their first litter.

What are the factors to the Fast, Intensive Reproductive Investment?

Reaches sexual maturity at one month, produces litters of six to ten offspring every month.

What are the factors to the Slow, Gradual Reproductive Investment?

Reaches sexual maturity at one year, produces about one offspring per year.

An organisms investment pattern in growth, reproduction, and survival is described by what?

Its life history.