Chapter 6 Flashcards
Extant /Extinct
Species that do have at least on individual alive in the world/The species no longer exists
Locally extinct (Extirpation)
Species are no longer found in a specific area.
Ecologically extinct
Species exist but its numbers are so low that it no longer fits its roll in the ecosystem
Extinct in the Wild
No natural population exists, but the species remains in captivity
Endemic
Species found in a specific location and no where else
Why is an endemic species at greater risk of extinction?
Because they are only found in a particular area, have limited defenses against exotics and cannot migrate away
How does the time of human contact (or arrival) affect the number of species recently extinct and currently threatened with extinction?
Increases
How has bird diversity changed with waves of human colonization on Hawaii? What are some of the reasons bird species have been lost?
-Decreased
-introduction of exotic species to islands
Consider the impact of humans on the extinction rate – is this something new for our species?
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
What is the background extinction rate (in MSY)? How is it calculated?
-1 mil
-Fossil records
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?
-1,000 – 10,000 times the background rate
-expected to increase (50%)
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?
-Critically endangered, Endangered, Vulnerable
-We cant tell how many eukaryotes there are
How many mass extinction events have occurred? What is the threshold for an extinction event to be a mass extinction event?
-5
->75% species lost
What is the largest mass extinction event? What may have contributed to it? Can you relate this to current changes in ocean chemistry?
-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
What may be the sixth major extinction event? Is this inevitable?
-Antropocene
-Can be fixed if we get our act together
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?
-50%
-10%
What assumptions are included in species -area models? How could these assumptions be violated?
-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
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.
-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
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?)
-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
How can island biogeography be applied monophagous insects (feed on just one tree species!)? To alpine habitats? To National Parks and Reserves?
-These habitats are similar to islands, more closed off than normal habitats
-Specialized
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?
-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)
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?
-The smaller the area, the less species richness
-Tested on Florida keys island, Mads Island smaller by cutting down mangroves
Population characters?
-Small pop size
-Declining pop size
-low pop density, Allee effect, cant fully function as a species.
-Have one or few populations
Distribution?
-Require a large home range
-Have a narrow geographic range
-Endemic species
