Chapter 6

Question 1

Extant /Extinct

Answer 1

Species that do have at least on individual alive in the world/The species no longer exists

Question 2

Locally extinct (Extirpation)

Answer 2

Species are no longer found in a specific area.

Question 3

Ecologically extinct

Answer 3

Species exist but its numbers are so low that it no longer fits its roll in the ecosystem

Question 4

Extinct in the Wild

Answer 4

No natural population exists, but the species remains in captivity

Question 5

Endemic

Answer 5

Species found in a specific location and no where else

Question 6

Why is an endemic species at greater risk of extinction?

Answer 6

Because they are only found in a particular area, have limited defenses against exotics and cannot migrate away

Question 7

How does the time of human contact (or arrival) affect the number of species recently extinct and currently threatened with extinction?

Answer 7

Increases

Question 8

How has bird diversity changed with waves of human colonization on Hawaii? What are some of the reasons bird species have been lost?

Answer 8

-Decreased
-introduction of exotic species to islands

Question 9

Consider the impact of humans on the extinction rate – is this something new for our species?

Answer 9

It has definitely increased since we’ve advanced technologically and started moving environments, but we’ve always caused things like this. Species will/ and did, naturally go extinct

Question 10

What is the background extinction rate (in MSY)? How is it calculated?

Answer 10

-1 mil
-Fossil records

Question 11

How do current rates of extinction compare to the estimated background extinction rate? How is the expected extinction rate projected to change in the future?

Answer 11

-1,000 – 10,000 times the background rate
-expected to increase (50%)

Question 12

What IUCN categories are used for species that are threatened with extinction? Is the % of threatened species available for most groups of Eukaryotes? Why not?

Answer 12

-Critically endangered, Endangered, Vulnerable
-We cant tell how many eukaryotes there are

Question 13

How many mass extinction events have occurred? What is the threshold for an extinction event to be a mass extinction event?

Answer 13

-5
->75% species lost

Question 14

What is the largest mass extinction event? What may have contributed to it? Can you relate this to current changes in ocean chemistry?

Answer 14

-Permian
-Switch from palaeozoic to Mesozoic
–The water levels were rising, mass volcanic eruptions, oceans got warmer and more acidic, not good for marine life
-Water levels rising and decreased pH similar to todays ocean

Question 15

What may be the sixth major extinction event? Is this inevitable?

Answer 15

-Antropocene
-Can be fixed if we get our act together

Question 16

Using the species area curve covered in lecture, how much of the habitat would you have to protect to preserve 90% of the species? What about 50% of the species?

Answer 16

-50%
-10%

Question 17

What assumptions are included in species -area models? How could these assumptions be violated?

Answer 17

-Assumes species have typical species area curves/ estimates may vary for species with wide vs narrow ranges
-Assumes species are eliminated from areas that are cleared of forest/ some species will survive the deforestation
-Assumes habitat is eliminated at random/ we may be able to preserve critical habitats or areas with high species richness
-Fragmentation of habitat can make a difference/ could make it worse

Question 18

What are the basic points of Island Biogeography theory as presented by MacArthur and Wilson? Your explanation should include all of the following: change in immigration rates, extinction rates, island size, island distance, species pool, dynamic equilibrium.

Answer 18

-The number of species on an island tends towards an equilibrium number
-Rate of immigration decreases as the # of species on the island increases
-The rate of extinction increases as the number if species increases
-Large islands have more species than smaller islands, and more space for populations (decrease risk of extinction)
-Islands closer to the mainland have more species and higher immigration rates (far islands opposite
-species that could potentially colonize and inhabit a focal habitat area
-composition of species change

Question 19

What changes have been made to the basic theory of island biogeography? (Could you discuss the target and rescue effects? What do these relate to? How do these differ from MacArthur and Wilson’s ideas?)

Answer 19

-Island size and distance (not the only cases)
-Target rate: the rate of immigration depends on the islands size (large=high, small=low)
-Resue effect: the distance from an island to a source pool of potential colonists also affects rate of extinction

Question 20

How can island biogeography be applied monophagous insects (feed on just one tree species!)? To alpine habitats? To National Parks and Reserves?

Answer 20

-These habitats are similar to islands, more closed off than normal habitats
-Specialized

Question 21

3 main predictions can be drawn from MacArthur and Wilson’s theory of Island Biogeography. What are they and which of these are well supported by experimental evidence?

Answer 21

-The number of species should increase with increasing island size (well supported)
-The number of species should decrease with increasing distance of the island from the source pool (well Supported)
-The turnover of species should be considerable (little support)

Question 22

The basic theory of island biogeography states that island size (itself) is related to the dynamic equilibrium of species found. Or is the higher number of species (on larger islands) due to the higher number of habitats found on larger islands?? How did Simberloff’s (1976) with Mangroves test this idea?

Answer 22

-The smaller the area, the less species richness
-Tested on Florida keys island, Mads Island smaller by cutting down mangroves

Question 23

Population characters?

Answer 23

-Small pop size
-Declining pop size
-low pop density, Allee effect, cant fully function as a species.
-Have one or few populations

Question 24

Distribution?

Answer 24

-Require a large home range
-Have a narrow geographic range
-Endemic species

Question 25

Home Range?

Answer 25

-If the habitat size is decreased or fragmented, it may not be able to support the animal

Question 26

Body size?

Answer 26

-Often require a larger home range
-Are more obvious to humans
-Often have longer generation times (lower reproductive rates)

Question 27

Dispersal ability?

Answer 27

-Low dispersal capabilities, habitat is often fragmented, species that cannot cross this boundaries are at greater risk

Question 28

Migration, aggregations?

Answer 28

-Require at least 2 specific habitats
-Doubles the chances that they will be impacted by human action

Question 29

Specialists or stability needs?

Answer 29

-Slight changes in the environment can have a larger impact (extinction)
-Species may require specific prey items and physical conditions
-Symbiotic association: If one species has a close relationship with another, the loss of one species may lead to the loss of another.
-habitat degradation can drastically change the conditions
-specialists may not be able to tolerate change
-Low dispersal = a species may not be able to move to a new aera or recognize an area often a disturbance

Question 30

k & r selection?

Answer 30

-k is most likely to be affected by humans because of their larger size and larger habitat

Question 31

History with (and value to) humans?

Answer 31

-The number of species tends to decline after humans colonize the area
-over harvesting can lead to a decline in pop

Question 32

How might these factors apply to a frog? A black bear? A sea turtle? Etc

Answer 32

-Frogs are smaller, so they are less likely to be affected because of migration, body size or distribution, however they’re specialists so they may be affected by habitat destruction/degradation or dispersal activity.
-Black bear are likely to be affected because of distribution, body size, home range, humans, and the fact that they are a K animal.
-Sea turtles are likely to be affected by distribution, migration, population characters, and humans

Question 33

What is the allee effect? How is this different from the concept of ecological extinction?

Answer 33

-They are not able to do what they need to within the species
-They are not able to do their job in the ecosystem

Question 34

What is a paleoendemic and neoendemic species? Why might looking for areas of neoendemism be useful for conserving biodiversity?

Answer 34

-Ancient species whose relatives have gone extinct, or a relict of a once broader distribution, now restricted to a smaller region
-Recently evolved from close relatives
-Because they will be close enough to their close relatives but more adapted to the environment.