Chapter 6

Question 1

Population

Answer 1

The individuals that belong to the same species and live in a given area at a particular time.

Question 2

Community

Answer 2

All of the populations of organisms within a given area.

Question 3

Population Ecology

Answer 3

The study of factors that cause populations to increase or decrease.

Question 4

Population Size (N)

Answer 4

The total number of individuals within a defined area at a given time.

Question 5

Population Density

Answer 5

The number of individuals per unit area at a given time

Question 6

Population Distrabution

Answer 6

A description of how individuals are distributed with respect to another.

Question 7

Sex Ratio

Answer 7

The ratio of males to females in a population

Question 8

Age Structure

Answer 8

A description of how many individuals fit into particular age categories in a population

Question 9

Limiting Resource

Answer 9

A resource that a population cannot live without and that occurs in quarantines lower than the population would require to increase size.

Question 10

Density-dependent Factor

Answer 10

A factor that influences an individual’s probability of survival and reproduction in a manner that depends on the size of a population

Question 11

Random Distribution

Answer 11

Resources are distributed evenly or sporadically.

Question 12

Uniform Distribution

Answer 12

Organisms are spread out in a fairly regular pattern.

Question 13

Clumped Distribution

Answer 13

Individuals are clustered in groups.

Question 14

Carrying capacity (K)

Answer 14

The limit of how many individuals in a population the environment can sustain

Question 15

Density-independent factor

Answer 15

A factor that has the same effect on an individual’s probability of survival and the amount of reproduction at any population size

Question 16

Population growth models

Answer 16

Mathematical equations that can be used to predict population size at any moment in time.

Question 17

Population growth rate

Answer 17

The number of offspring an individual can produce in a given time period, minus the deaths of the individual or its offspring during the same period.

Question 18

Intrinsic growth rate (r)

Answer 18

The maximum potential for growth of a population under ideal conditions with unlimited resources.

Question 19

Exponential growth model

Answer 19

(Nt = Noert) A growth model that estimates a population’s future size (ND after a period of time (t), based on the intrinsic growth rate (r) and the number of reproducing individuals currently in the population (No).

Question 20

J-shaped curve

Answer 20

The curves of the exponential growth model when graphed.

Question 21

Logistic growth model

Answer 21

A growth model that describes a population whose growth is initially exponential, but slows as the population approaches the carrying capacity of the environment.

Question 22

S-shaped curve

Answer 22

The shape of the logistic growth model when graphed.

Question 23

Overshoot

Answer 23

When a population becomes larger than the environment’s carrying capacity.

Question 24

Die-off

Answer 24

A rapid decline in the population due to death.

Question 25

K-selected species

Answer 25

A species with a low intrinsic growth rate that causes the population to increase slowly until it reaches carrying capacity.

Question 26

r-selected species

Answer 26

A species that has a high intrinsic growth rate, which often leads to population overshoots and die-offs.

Question 27

Survivorship curve

Answer 27

A graph that represents the distinct patterns of species survival as a function of age.

Question 28

Type I survivorship curve

Answer 28

A pattern of survival over time in which there is high survival throughout most of the life span, but then individuals start to die in large numbers as they approach old age.

Question 29

Type II survivorship curve

Answer 29

A pattern of survival over time in which there is a relatively constant decline in survivorship throughout most of the life span.

Question 30

Type Ill survivorship curve

Answer 30

A pattern of survival over time in which there is low survivorship early in life with few individuals reaching adulthood.

Question 31

Corridor

Answer 31

Strips of natural habitat that connect populations.

Question 32

Metapopulation

Answer 32

A group of spatially distinct populations that are connected by occasional movements of individuals between them.

Question 33

Inbreeding depression

Answer 33

When individuals with similar genotypes—typically relatives—breed with each other and produce offspring that have an impaired ability to survive and reproduce.

Question 34

Community ecology

Answer 34

The study of interactions between species.

Question 35

Symbiotic relationship

Answer 35

The relationship between two species that live in close association with each other.

Question 36

Competition

Answer 36

The struggle of individuals to obtain a shared limiting resource.

Question 37

Competitive exclusion principle

Answer 37

The principle stat-ing that two species competing for the same limiting resource cannot coexist.

Question 38

Resource partitioning

Answer 38

When two species divide a resource based on differences in their behavior or morphology.

Question 39

Mutualism

Answer 39

An interaction between two species that increases the chances of survival or reproduction for both species.

Question 40

Commensalism

Answer 40

A relationship between species in which one species benefits and the other species is neither harmed nor helped.

Question 41

Keystone species

Answer 41

A species that is not very abundant but has large effects on an ecological community.

Question 42

Ecological succession

Answer 42

The predictable replacement of one group of species by another group of species over time.

Question 43

Primary succession

Answer 43

Ecological succession occurring on surfaces that are initially devoid of soil.

Question 44

Secondary succession

Answer 44

The succession of plant life that occurs in areas that have been disturbed but have not lost their soil.

Question 45

Pioneer species

Answer 45

A species that can colonize new areas rapidly and grow well in full sunshine.

Question 46

Climax community

Answer 46

Historically described as the final stage of succession.

Question 47

Rate of Growth Formula

Answer 47

Original - Final / Original