Lecture 4

Question 1

mark-recapture equation

Answer 1

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 2

range (distribution)

Answer 2

area over which a specific population occurs

Question 3

two ways to estimate abundance

Answer 3

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

Question 4

examples of organisms that demonstrate clumped distribution

Answer 4

• 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 5

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

Answer 5

• 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)

Question 6

population size

Answer 6

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

Question 7

geographic range

Answer 7

area over which all populations of a species reside

Question 8

the importance of corridors between subpopulation habitat patches

Answer 8

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

Question 9

three types of individual distribution

Answer 9

• 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 10

subpopulation vs. metapopulation

Answer 10

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

Question 11

Richard Levins’ definition of metapopulations

Answer 11

• 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 12

examples of organisms that demonstrate uniform distribution

Answer 12

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

Question 13

three ways individuals move within a population

Answer 13

• dispersal: permanent 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 14

two things population abundance is influenced by

Answer 14

population density and population range

Question 15

reasons why population abundance has to be estimated

Answer 15

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

Question 16

examples of organisms that demonstrate random distribution

Answer 16

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

Question 17

the importance of empty patches in a metapopulation

Answer 17

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

Question 18

population density

Answer 18

the number of individuals per unit area

Question 19

population abundance

Answer 19

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