Chapter 11 - Population distributions

Question 1

Differentiate between fundamental and realized niches.

Answer 1

Fundamental niche: The range of abiotic conditions under which species can persist.
Realized niche: The range of abiotic and biotic condition under which a species persists.

Question 2

Why might the fundamental and realized niches of a species not be the same?

Answer 2

Available environments with conditions of the fundamental niche may remain unoccupied because of other species within that location, forcing the species in question to inhabit a different area (i.e., the realized niche).

Question 3

What is a geographic range? Will you necessarily find individuals in every part of a species’ geographic range?

Answer 3

Geographic range is a measure of the total area covered by a population. Individuals often do not occupy every location within their range, however.

Question 4

What factors influence the abundance of individuals within certain locations of their geographic range?

Answer 4

Climate, topography, soil, vegetation structure.

Question 5

Why might it be important to know the fundamental niche of a species?

Answer 5

Can help biologists to bring back a species from the brink of extinction by knowing the conditions they can survive under. Can assess the probability of a pest spreading by understanding the conditions it thrives under. Can also be used to predict how environmental changes may affect a species.

Question 6

What is ecological niche modelling?

Answer 6

The process of determining the suitable habitat conditions for a species.

Question 7

What is an ecological envelope?

Answer 7

The range of ecological conditions that are predicted to be suitable for a species.

Question 8

What are the five important characteristics of population distributions?

Answer 8

Geographic range, abundance, density, dispersion and dispersal.

Question 9

Why is geographic range an important measure?

Answer 9

It tells us how large an area a population occupies. Larger geographic ranges are less vulnerable to events such as natural disasters.

Question 10

What is an endemic species?

Answer 10

A species that lives in a single, often isolated, location.

Question 11

What is a cosmopolitan species?

Answer 11

Species with very large geographic ranges that can span several continents.

Question 12

What is abundance? Why is it important?

Answer 12

The total number of individuals in a population that exist within a defined area. Provides a measure of whether a population is thriving or on the brink of extinction.

Question 13

What is population density? Why is it important?

Answer 13

The number of individuals within a particular area. If the population density is lower than what the habitat can support, the population can continue to grow. If it is larger than what can be supported by the environment, individuals will have to leave the area.

Question 14

Where are individuals typically concentrated within their population’s geographic range?

Answer 14

The center.

Question 15

What is dispersion?

Answer 15

The spacing of individuals with respect to one another within the geographic range of a population.

Question 16

What type of dispersion patterns are there?

Answer 16

Clustered, evenly spaced, random.

Question 17

What is clustered dispersion? How might this occur?

Answer 17

A pattern of population dispersion in which individuals are aggregated in discrete groups. Can be caused by individuals living in social groups or offspring remaining close to their parents.

Question 18

What is evenly spaced dispersion? When might this occur?

Answer 18

A pattern of dispersion of a population in which each individuals maintains a uniform distance between itself and its neighbours. Occurs in agricultural settings and in populations that defend territories. Can also be affected by competition.

Question 19

What is random dispersion? How common is it?

Answer 19

A pattern of dispersion of a population in which the position of each individual is independent of the position of other individuals in the population. It is not common in nature.

Question 20

What is dispersal?

Answer 20

The movement of individuals from one area to another.

Question 21

How might the location and number of individuals be quantified?

Answer 21

Through surveys or censuses.

Question 22

What is a census? A survey?

Answer 22

Census counts every individual in a population. A survey counts a subset of the population.

Question 23

Why might a survey be used instead of a census.

Answer 23

It is not feasible to count every individual within a population for most species.

Question 24

What are area- and volume-based surveys?

Answer 24

Surveys that define the boundaries of an area or volume and then count all of the individuals in the space.

Question 25

What are line-transect surveys?

Answer 25

Surveys that count the number of individuals observed as one moves along a line.

Question 26

What is a limitation of area- and volume-based and line-transect studies? What type of survey can be used in this instance?

Answer 26

Area- and volume-based and line-transect studies are not as useful when studying populations that move around a lot or are well-camouflaged. Mark-recapture surveys are more useful for these situations.

Question 27

What is a mark-recapture survey?

Answer 27

A method of population estimation in which researchers capture and mark a subset of a population from an area, return it to the area, and then capture a second sample of the population after some time has passed.

Question 28

What is necessary in order to quantify the dispersal of individuals?

Answer 28

The source of individuals must be identified.

Question 29

What is lifetime dispersal distance? What can this be used to estimate?

Answer 29

The average distance an individual moves from where it was hatched or born to where it reproduces. This can be used to estimate how rapidly a growing population can increase its geographic range.

Question 30

How are population abundance and geographic range connected?

Answer 30

Populations with high abundance also have a large geographic range.

Question 31

How are population density and adult body size connected?

Answer 31

The density of a population is negatively correlated to the body size of the species.

Question 32

What is a dispersal limitation? What is a common barrier?

Answer 32

The absence of a population from suitable habitat because of barriers to dispersal. A common barrier is the presence of large expanses of inhospitable habitat that an organism cannot cross. For example, a highway.

Question 33

What is a habitat corridor?

Answer 33

A strip of favourable habitat located between two large patches of habitat that facilitates dispersal.

Question 34

What is ideal free distribution? How common is this?

Answer 34

When individuals distribute themselves among different habitats in a way that allows them to have the same per capita benefit. Individuals in nature rarely match the ideal expectations.

Question 35

What are subpopulations?

Answer 35

When a larger population is broken up into smaller groups that live in isolated patches.

Question 36

What is the basic metapopulation model?

Answer 36

A model that describes a scenario in which there are patches of suitable habitat embedded within a matrix of unsuitable habitat.

Question 37

What does the basic metapopulation model emphasize?

Answer 37

How colonization and extinction events can affect the proportion of total suitable habitats that are occupied.

Question 38

What is the source-sink metapopulation model?

Answer 38

Builds upon the basic metapopulation model and accounts for the fact that not all patches of suitable habitat are of equal quality.

Question 39

Differentiate between source and sink subpopulations.

Answer 39

Source: In high-quality habitats, subpopulations that serve as a source of dispersers to maintain the subpopulation within a metapopulation. Sink: In low-quality habitats, subpopulations that rely on outside dispersers to maintain the subpopulation within a metapopulation.

Question 40

What is the landscape metapopulation model?

Answer 40

A population model that considers both differences in the quality of the suitable patches and the quality of the surrounding matrix.

Question 41

What assumptions need to be made in mark and recapture surveys?

Answer 41

Tags are not lost. Marked individuals are just as likely to be captured as non-marked individuals. Populations remain constant. Tags do not influence an individual's behaviour

Question 42

Provide some examples of tags in mark-recapture studies.

Answer 42

Fin tags on fish, paper tags on butterflies, bird banding, markers on mammals, pictures of humpback whale tails.