Lecture 4

Question 1

range (distribution)

Answer 1

area over which a specific population occurs

Question 2

geographic range

Answer 2

area over which all populations of a species reside

Question 3

subpopulation vs. metapopulation

Answer 3

• subpopulation: a subset of a larger population
• metapopulation: a collection of subpopulations that are exchanging genetic information (connected by gene flow)

Question 4

population size

Answer 4

the number of individuals in the total population; density × range

Question 5

population abundance

Answer 5

the number of individuals in a given area (can vary across the range)

Question 6

two things population abundance is influenced by

Answer 6

population density and population range

Question 7

population density

Answer 7

the number of individuals per unit area

Question 8

three types of individual distribution

Answer 8

• random: the position of each individual is independent of the position of the other individuals in the population
• uniform: individuals are evenly spaced out, often due to negative interactions (i.e. competition, territoriality)
• clumped: individuals occur in groups, due to location of resources, suitable habitats, or protection from predators (social units)

Question 9

examples of organisms that demonstrate random distribution

Answer 9

• trees
• wind-dispersed seeds
• animal-dispersed seeds, and the animals that eat them

Question 10

examples of organisms that demonstrate uniform distribution

Answer 10

nesting birds (e.g. penguins on breeding grouns)

Question 11

examples of organisms that demonstrate clumped distribution

Answer 11

• social animals (e.g. wolves, lions)
• animals that eat unevenly distributed food (i.e. seedlings can clump around parent plants if gravity-dispersed)
• plants that are dispersed by small scatter-hoarder animals

Question 12

reasons why population abundance has to be estimated

Answer 12

• hard to see microscopic/dull-coloured organisms
• some organisms are only present during reproduction
• to measure size (especially for plants; trees)

Question 13

two ways to estimate abundance

Answer 13

• quadrats: splitting a range up into quadrats (square frames)
• mark-recapture: animals are captured, marked, and then recaptured

Question 14

mark-recapture equation

Answer 14

N/M = n/R

• N = unknown population size
• M = number of individuals marked
• n = number of individuals recaptured
• R = number of recaptured individuals that are marked

Question 15

three ways individuals move within a population

Answer 15

• dispersal: movement of individuals/genes into a certain space
• emigration: movement of individuals/genes out of a subpopulation
• immigration: movement of individuals/genes into a subpopulation

Question 16

Richard Levins’ definition of metapopulations

Answer 16

• a set of local subpopulations that persist in balance between individuals that reproduce and die within local patches, and their offspring disperse into other patches
• emigration/immigration is rare

Question 17

the importance of corridors between subpopulation habitat patches

Answer 17

• when patches are isolated, more species become extinct
• when patches are connected by corridors, fewer extincts become extinct

Question 18

the importance of empty patches in a metapopulation

Answer 18

a certain number of empty patches is necessary for a stable metapopulation, to allow for offspring dispersal to patches

Question 19

four conditions necessary for stable metapopulations, following Levins’ Classic Model

Answer 19

• suitable habitats occur in patches
• all populations must have a substantial risk of local extinction
• habitat patches can’t be too isolated, to allow for recolonization after local extinction
• the dynamics of the subpopulations aren’t synchronized (or the entire metapopulation could go extinct at once)