Natural Causes of Population Decline and Extinciton

Question 1

What is the Theory of Island Biogeography?

Answer 1

The number of species of a given taxon represents a dynamic equilibrium between the rate of immigration of new colonizing species and the rate of extinction of previously established ones.

Question 2

What is an Island characterized by?

Answer 2

• Various Sizes
• Various Distances

Question 3

What is the Species-Area curve?

Answer 3

A tool used to estimate biodiversity in a habitat, where number of species on an island or patch increases as area increases.

Question 4

What is the equation for the species-area curve?

Answer 4

S = cA (z-superscript)

Question 5

What are the two factors of Island Biogeography?

Answer 5

Island Size & Island Isolation

Question 6

Larger islands have greater range of ________.

Answer 6

Microhabitats

Question 7

Near islands are more likely to be ___________.

Answer 7

Colonized

Question 8

_______ island populations are more likely to go extinct.

Answer 8

Small

Question 9

True or False: As the number of resident species increases the number of new immigrants decreases because there are fewer new potential immigrants from the source pool.

Answer 9

True.

Question 10

Given a finite resource base, as number of species increases, population size of individual species must _________.

Answer 10

decline

Question 11

What theory does the Turnover Rate apply to?

Answer 11

Theory of Island Biogeography

Question 12

What is the Turnover Rate?

Answer 12

The rate at which species are lost and new ones gained.

Question 13

Define the Rescue Effect:

Answer 13

Extinction of a dwindling population may be slowed or halted through immigration of new individuals.

Question 14

What is turnover rate influenced by?

Answer 14

1. Island Size (Patchy)
2. Nearness to other sources immigrants

Question 15

What are some types of islands?

Answer 15

• Mountaintops
• Bogs
• Ponds
• Dunes
• Insects and their parasites

Question 16

What is the rule of thumb in the Theory of Island Biogeography?

Answer 16

A tenfold increase in area leads to a doubling of the number of species.

Question 17

Define a Metapopulation:

Answer 17

If they are far enough apart to exist as distinct, partially isolated sub-populations each possessing its own population dynamics, linked only through dispersal (emigration/immigration).

Question 18

_____ Effect: The loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population.

Answer 18

Founder Effect

Question 19

Define the Genetic Bottleneck:

Answer 19

A sharp reduction in the size of a population due to environmental events such as famines, earthquakes, floods, fires, disease, and droughts; or human activities such as specicide, widespread violence or intentional culling.

Question 20

What is an example of a genetic bottleneck?

Answer 20

Elephant Seals

Question 21

Define Random Genetic Drift:

Answer 21

The changes that occur in the frequency of alleles in a population due to random chance.

Question 22

Define Inbreeding:

Answer 22

The breeding between close relatives.

Question 23

What are the 4 genetic aspects of Metapopulations?

Answer 23

1. Founder Effect
2. Genetic Bottleneck
3. Random Genetic Drift
4. Inbreeding

Question 24

Define the Minimum Viable Population:

Answer 24

The minimum number of individuals that will ensure the persistence of a metapopulation for some set period of time (100 years commonly used).

Question 25

What is the 50 / 500 rule for an effective population size?

Answer 25

An effective population sizeof 500 is required to offset the effects of genetic drift while a minimum of 50 is needed to avoid inbreeding depression.

Question 26

What is an effective population size?

Answer 26

the number of breeding adults that pass gametes on to the next generation, not just those capable of breeding.

Question 27

What are some limitations of a minimum viable population?

Answer 27

smaller population sizes are at risk for extinction in a shorter period of time.

Question 28

PRACTICE THE EXTINCTION VORTEX

Answer 28

Week 1: Slide 26

Question 29

Define a Niche:

Answer 29

A multidimensional space occupied by a species, defined by position along physical, environmental and temporal gradients.

Question 30

What is an example of a niche?

Answer 30

Crayfish in MB, its like having a McDonalds in a mall, you won't often see two in the same place, one will outperform the other.

Question 31

Explain competition in terms of a niche:

Answer 31

If two species occupy the same niche, one will eventually eliminate the other through competition.

Question 32

What is Resource Portioning?

Answer 32

Similar species usually differ in some habit or feeding requirement that allows them to co-exist.

Question 33

True or False: Disease and Parasitism often work in concert with other factors.

Answer 33

True, it either weakens a population so other factors (pollution, climate change, etc.) have a greater impact

Question 34

What type of case is the Chestnut Blight?

Answer 34

Disease / Parasitism, a fungus introduced accidentally to NY around 1900 from Asia.

Question 35

What are the Wood Bison an example of?

Answer 35

Hybridization