APES Ch 8 Population Ecology

environmental resistance

All the limiting factors that act together to limit the growth of a population. See biotic potential, limiting factor.

A population's growth rate will increase as the population reaches its carrying capacity.

FALSE

Because humans can control over their environment and readily adapt to change, human populations can never experience a population crash.

FALSE

Highly developed countries have such a high population growth rate because the birth rate is so high.

FALSE

It is always an advantage to reproduce sexually.

FALSE

K-selected species tend to be opportunists and can fill a niche by reproducing rapidly until carrying capacity is reached.

FALSE

On a survivorship curve, r-selected species tend to demonstrate late loss.

FALSE

The human population can continue yielding a J-shaped growth curve because of technology.

FALSE

When a population overshoots the environment's carrying capacity, species diversity becomes constant.

FALSE

When a population reaches carrying capacity, the population's biotic potential gradually declines to a consistent value slightly greater than the original.

FALSE

S-shaped curve

Leveling off of an exponential, J-shaped curve when a rapidly growing population exceeds the carrying capacity of its environment and ceases to grow.

population dynamics

Major abiotic and biotic factors that tend to increase or decrease the population size and age and sex composition of a species.

reproduction

Production of offspring by one or more parents.

intrinsic rate of increase (r)

Rate at which a population could grow if it had unlimited resources. Compare environmental resistance.

sexual reproduction

Reproduction in organisms that produce offspring by combining sex cells or gametes (such as ovum and sperm) from both parents. This produces offspring that have combinations of traits from their parents. Compare asexual reproduction.

asexual reproduction

Reproduction in which a mother cell divides to produce two identical daughter cells that are clones of the mother cell. This type of reproduction is common in single-celled organisms. Compare sexual reproduction.

K-strategists

See K-selected species.

J-shaped curve

Curve with a shape similar to that of the letter J; can represent prolonged exponential growth. See exponential growth.

population dispersion

General pattern in which the members of a population are arranged throughout its habitat.

survivorship curve

Graph showing the number of survivors in different age groups for a particular species.

linear growth

Growth in which a quantity increases by some fixed amount during each unit of time. An example is growth that increases in the sequence 2, 4, 6, 8, 10, and so on. Compare exponential growth.

exponential growth

Growth in which some quantity, such as population size or economic output, increases at a constant rate per unit of time. An example is the growth sequence 2, 4, 8, 16, 32, 64 and so on; when the increase in quantity over time is plotted, this type of growth yields a curve shaped like the letter J. Compare linear growth.

carrying capacity (K)

Maximum population of a particular species that a given habitat can support over a given period.

biotic potential

Maximum rate at which the population of a given species can increase when there are no limits on its rate of growth. See environmental resistance.

population size

Number of individuals making up a population's gene pool.

population density

Number of organisms in a particular population found in a specified area or volume.

logistic growth

Pattern in which exponential population growth occurs when the population is small, and population growth decreases steadily with time as the population approaches the carrying capacity. See S-shaped curve.

age structure

Percentage of the population (or number of people of each sex) at each age level in a population.

reproductive potential

See biotic potential.

r-strategists

See r-selected species.

dieback

Sharp reduction in the population of a species when its numbers exceed the carrying capacity of its habitat. See carrying capacity.

K-selected species

Species that produce a few, often fairly large offspring but invest a great deal of time and energy to ensure that most of those offspring reach reproductive age. Compare r-selected species.

r-selected species

Species that reproduce early in their life span and produce large numbers of usually small and short-lived offspring in a short period. Compare K-selected species.

A population will increase in size when it is made up mostly of individuals in the prereproductive age category.

TRUE

Carrying capacity (K) is a result of the combination of biotic potential and environmental resistance.

TRUE

Carrying capacity is the population size (or density) at which the environment is saturated.

TRUE

No population can grow indefinitely because there is always some limiting factor that keeps a population in check.

TRUE

The effect of population increase or environmental resistance is not felt instantly in most cases.

TRUE

The size of a species' population, be that animal or human, is influenced by births, deaths, immigration, and emigration.

TRUE

population distribution

Variation of population density over a particular geographic area. For example, a country has a high population density in its urban areas and a much lower population density in rural areas.