chp 20 biology

Why are truly random distributions rare in nature?

- Individuals of a particular species often need certain types of conditions to survive and grow, so more individuals are found in these areas. - Many species have social behaviors that promote clusters of individuals for increasing foraging success or for predator avoidance. - Resources are unevenly distributed across most landscapes.

When moose first arrived on Isle Royale and found a habitat without predators, the moose population _____.

- grew exponentially, and then crashed due to lack of food. - could be categorized as going through a cycle of "boom and bust" population dynamics. - re-grew after a starvation period that allowed the vegetation to recover. - was not regulated by predator-prey interactions.

ecosystem,

A biological community of interacting organisms and their physical environment.

Which ecological definition is incorrect?

A community is made up of biotic and nonliving components.

density-independent factor

A factor that can influence population size and growth regardless of the numbers and crowding within a population (for example, weather).

population density

A measurement of the number of people per given unit of land

logistic growth

Growth pattern in which a population's growth rate slows or stops following a period of exponential growth

exponential growth.

Growth pattern in which the individuals in a population reproduce at a constant rate

carrying capacity

Largest number of individuals of a population that a environment can support

How have warmer-than-normal climatic conditions affected moose populations on Isle Royale?

Moose escaped the heat by resting in the shade, but then had less time for eating, which resulted in thinner moose that were not as prepared to survive winter temperatures. Tick populations have grown and they have fed on the moose, which resulted in blood loss and higher death rates for moose. An increase in the tick population has resulted in weight loss for the moose, which increased their death rate.

Immigration

Movement of individuals into a population

biotic

Refers to the living components of an environment.

abiotic

Refers to the nonliving components of an environment, such as temperature and precipitation.

ecology

Scientific study of interactions among organisms and between organisms and their environment

Which statement is true of distribution patterns in nature?

Uniform distribution allows individual organisms to maximize space between them.

Ecologists often study the spatial distribution of animals. Which of these descriptions of common distribution patterns is incorrect?

Uniform: moose are highly territorial creatures and move around an island habitat in large groups.

Which event or condition is a density-independent factor that could influence population growth?

a volcanic eruption that covers an island in a layer of lava

Imagine a system where a finch feeds on thistle seeds and the finch population size is linked to the productivity of the thistle, and the thistle population size is related to foraging pressure of the finch population. This is an example of population dynamics at the _____ level.

community

density-dependent factors

factor that limits a population more as population density increases

Which of these is NOT an example of something that ecologists would generally study?

how the mitochondria of a mouse function in its cells

Ecologists study organisms at a number of levels with different numbers of components. Which sequence correctly orders these levels, from smallest to largest?

individual, population, community, ecosystem

Once the carrying capacity of an environment is reached, the population generally _____.

may fluctuate by slightly exceeding the carrying capacity, and then dropping below it may experience cycles of "boom and bust" cannot continue growing exponentially

emmigration

movement of individuals out of a population

Which phrase is NOT a biotic factor affecting population growth of moose on Isle Royale?

summer temperatures

All of these statements regarding ecosystems are correct EXCEPT _____.

sunlight and water are good examples of living components of an ecosystem

growth rate,

the amount by which a population's size changes in a given time

Growth rates are _____.

the difference between birth and death rates in a population

dispersion pattern

the manner in which individuals in a population are spaced within their area

Population dynamics are influenced by birth and death rates. Which situation is NOT a factor that can cause early death for wolves on Isle Royale?

warmer temperatures causing tick populations that feed on wolves to increase dramatically, which causes wolves to lose blood and decreases their hunting abilities

Carrying capacity is NOT the point _____.

where additional resources are available only to individuals that immigrate into the population