lecture 6 - extinction

Question 1

local vs large scale extinction?

Answer 1

• local vs large scale - what does it entail to know if a species is extinct?
○ Looking for signs of the species at different age stages, recruitment, etc
○ Clear but becomes a large/impossible task

Question 2

what genetic method can be used to determine if a sp is extinct? what is lost with extinction?

Answer 2

• Pcr sequencing + genome data base - can see if you found something that was previously thought to be extinct
○ Expensive but cheaper than sending out more manual labor
Biodiversity lost with extinction - ecosystem becomes more vulnerable when biodiversity is eroded - all organisms are connected

Question 3

what is the ratchet concept?

Answer 3

• Extinction is a one way street - on a global scale there is no way to make a species return
• Ratchet can turn counter clockwise but not the other way - extinction is an accumulation of loss
○ we can build conservation units such as parks but it can still all be lost (politics, funding, etc)

Question 4

ex of global extinction - tasmanian tiger

Answer 4

• Proper extinction – the Tasmanian tiger, it was from Australia and it was a marsupial there was only one known to be in captivation but it died. It was a predator, which means that it is higher up on the food chain, which make it more vulnerable because there are less of them. Like a saber tooth tiger as well. Predator that had lower population more vulnerable to changes in the ecosystem.
• For less noticeable organism we don’t necessarily notice if it disappears.

Question 5

why is local extinction important

Answer 5

• distinct pops. Have distinct gene pools - founder effects, genetic exchange, environment
A local population can be critical to different scales of population and species. One aspect of having a variety of species in different places could mean that the population may be successful.

Question 6

st helena tree example - sp that can exist when protected but not in nature

Answer 6

• Ex. That st Helena ebony tree is essentially extinct despite it being able to grow well when in captivity or in other places, but it is under a lot of stress in its natural habitat

Question 7

functionally extinct?

Answer 7

• Functionally extinct- when the population are very low, like the caribou, affecting the ecological role that they used to have that will eventually be replaced by another organism.

Question 8

canadian act for sp at risk ?

Answer 8

• In Canada, we have the species at risk act- SARA. Says that the status of species are done by independent species , and form a omitted of endangered life in Canada.

Question 9

extirpated definition?

Answer 9

• Extirpated- a wildlife species that no longer exists in the wild in Canada but exists elsewhere.
• Species in Canada may have lower density and at a higher risk to become locally extinct because of the climate and how the species are distributed in Canada

Question 10

endangered def?

Answer 10

• Endangered – species facing imminent extirpation or extinction – species in concern
• Macro view of extinction- the big picture, we have information of earths past by the fossil record, non human induced extinction ( volcanoes, comets ext. )

Question 11

what is the background extinction rate?

Answer 11

• Estimating extinction – background extinction rate is around 0.0001%- 0.00001% per year based on fossil record. Observed extinction rate is 0.01% per year (what we see now)

Question 12

what era are we in? ex of our mass extinction- the dodo

Answer 12

• The Anthropocene era – era of humans. Of we imagine how future geologists will find in the strata from what we are leaving in the ground- like plastic, will have chemical signatures.
• The Dodo - did not adapt to the presence of humans, they are not human shy there is no fear response to humans/predators, so they go extinct because they are easy to obtain. - extinct bc we have samples of the birds + old paintings/mentions of them
• If speciation is less than the climate change then there might be a loss of species like extinction

Question 13

• How do we estimate the rate of extinction when we don’t know the quantity of species?

Answer 13

? There is a reliance on theoretical understandings of diversity. The bigger the area the more diversity there will be.
• Estimating extinction using species area relationships – S = CA^z

Question 14

• Wilson and McCarther method to measure extinction?

Answer 14

• Wilson and McCarther developed a graph of extinction and area of islands because they studied these islands and how species would move (look at the graph in the slides) islands that are father of the inland will have lower introduction of species, than those islands that are closer to the inland

Question 15

why are islands important for biodiversity?

Answer 15

• Islands in themselves are important for biodiversity because they have a lot of endemic organism (only live on that island)

Question 16

• Insular biogeography?

Answer 16

a reversed graph that shows how the loss of vegetation increases the loss of biodiversity. If you remove half the habitat, you lose 10% and if you lose 50% of habitat you lose 50% of species so on until extinction. But organisms are usually good at moving and changing their behaviour and moving to a place that does have their habitats.

Question 17

why might we care or not care about extinction?

Answer 17

○ Human conflict
○ Bias - prefer non-predators but higher in trophic pyramid = less numbers = more likely to be vulnerable
Looking at fossil record - bigger/higher up tend to go extinc

Question 18

COSEWIC endangered vs threatened?

Answer 18

Endangered: A wildlife species facing imminent extirpation or
extinction.
• Threatened: A wildlife species that is likely to become an
endangered if nothing is done to reverse the factors leading to its
extirpation or extinction.

Question 19

COSEWIC special concern?

Answer 19

pecial Concern: A wildlife species that may become threatened
or endangered because of a combination of biological
characteristics and identified threats

Question 20

COSEWIC data deficient or not at risk?

Answer 20

Data Deficient: A category that applies when the available
information is insufficient (a) to resolve a wildlife species’
eligibility for assessment or (b) to permit an assessment of the
wildlife species’ risk of extinction.
• Not At Risk: A wildlife species that has been evaluated and found
to be not at risk of extinction given the current circumstances.

Question 21

what impacts our estimates of extinction

Answer 21

• Quality of data impacts this - ballpark figure but regardless seems to be a mass extinction

Question 22

model of theory of island biogeography ? how can we reverse it

Answer 22

○ Smaller islands = higher extinction rate - less immigration
• Can reverse this model
○ Ie. Lose about half of the hhabitat = lose 10% of species
○ Often where habitats are destroyed- the number of species lost is not as severe as predicted by this model - bc of the ability of them to hang on longer than we think - the model has a dynamic idea - takes a longer time to meet that eq. than we assume

Question 23

what does a large home range imply

Answer 23

Large home range -implies a large amount of habitat needs to be used - ex vast migration of salmon from oceans to rivers/streams
More pressure points

Question 24

peka peka bat ex?

Answer 24

• Endemic to NZ
  
  • Limited in size of pops and number of pops
  • American shad - may stages at which pop can be bottle necked bc of vast migration

Question 25

extinction vortex?

Answer 25

• When you add all these factors together, they tend to have a positive reinforcement feedback
  
  • Vortex- slow decline
  • Demographic - smaller pop may have disproportionate representation - limited by smaller gene pool
  • H1 is a function of H0 which is a function of the effective pop size
  • Unequal sex ratio - genetic bottleneck if only a few individuals of a specific sex
  • Genetic structure - not just sheer numbers

Question 26

exs of the extinction vortex facotrs

Answer 26

small pop size - devils hole pup fish 
seasonal migration - american shad 
large home range - salmon 
limited dispersal ability- quino checkerspot butterfly 
large home range - panda

Question 27

beaver reintroduction?

Answer 27

hunted or harvested by people, reintroduced into ecosystems

Question 28

problems of small pops?

Answer 28

Loss of genetic diversity
• Outbreeding depression
• Loss of evolutionary flexibility
• Vulnerable to demographic stochasticity
• Vulnerable to environmental stochasticity

Question 29

loss of genetic diversity?

Answer 29

larger pops = greater genetic diversity 
Maintenance of
heterozygosity as a
function of effective
population size:
H1= {1-1/(2Ne)]H0
• Effective population size
(Ne) is the
approximately the
number of breeding
individuals

Question 30

consequences of reduced genetic diversity?

Answer 30

inbreeding depression - educed survival and fertility of offspring of related individuals.
• Outbreeding depression - happens when crosses between two genetically distant groups or populations result in a reduction of fitness.
• Loss of evolutionary flexibility

Question 31

Factors that influence effective population size (Ne

Answer 31

Unequal sex ratio
Variation in reproductive output
• Population fluctuations and bottlenecks- ex ngrongoro crater lion pop