Part II Flashcards
(39 cards)
1
Q
why is it difficult to estimate current rate of extinction?
A
- difficult to say w/ certainty that a species is extinct
- most species unknown to scientists, therefore extinct species also unknown
2
Q
cycles that generate climate changes short term
A
- earth revolves on its axis leading to alternating cooling and warming w/ solar radiation
- earth orbits sun, tilted axis generates annual climactic cycles b/w northern hemisphere tilted toward sun during half of the orbit, southern hemisphere tilted toward sun other half
- LEADS TO
- diurnal-nocturnal behaviour of animals
- seasonal growth and death of annual plants
3
Q
cycles that generate climate changes long term
A
- variaration of tilt of earth’s axis
- variation of shape of earth’s orbit around sun
- procession of equinoxes: distance form earth to sun cna either accentuate or ameliorite effects of axial tilt on weather
4
Q
3 concerning observations re:global warming
A
- greenhouse gases lead greenhouse effect
- increased concentration of gg lead to increase greenhouse effect
- mean global temperature has increased
5
Q
greenhouse gases
A
water vapor, carbon dioxide, methane, etc.
6
Q
greenhouse effect
A
gg allow solar radiation to penetrate atmosphere and warm earth’s surface and inhibit reradiation of energy back to space
7
Q
causes of global warming
A
- increased consumption of fossil fuels
- devasation of ecosystems (release gg)
- astronomical factors, increased photosynthesis (unpopular)
8
Q
will organisms be able to adapt to future climate change?
A
- have been able to adapt well in past but maybe not in future
- current pops. already stressed by habitat degradation and overexploitation
- stressed pops. are small and therefore have lower chance to produce offspring
- human alteration of landscapes has reduced quantity of suitable habitats and fragmented landscapes by roads, etc. decreasing odds of individuals arriving in new suitable habitat
- possible temps will rise to unprecedented levels
- melting ice caps reduce shoreline
- unprecedented rate of increase in temp
9
Q
why are rare species more vulnerable to extinction than common species?
A
- greater chance of pushed to extinction by environmental change
- environmental event may encompass species’ entire range
- demographic problems
- unbalanced sex ratio can limit birth rate
- more likely to happen to small pops.
- genetic problems
- inbreeding
- genetic drift
- bottlenecks
- restricted ability to adapt
10
Q
why are some species particularly sensitive to human-induced threats?
A
- limited adaptability and resilience
- may be due to low reproductive capacity, limited dispersal capabilities, inflexible habitat requirements, etc.
- human attention
- may be edible, extremely unpopular (e.g. bats)
- ecological overlap
- tied to human-preferred ecosystems (e.g. w/ fertile soil and benign climates)
- large home-range requirements
- cannot fit in among humans
11
Q
population
A
groups of individuals of some species occupying a defined area at same time
12
Q
meta populations
A
group of diff. patch pops.
13
Q
turnover
A
subpopulations appearing and disappearing due to colonization and local extinction
14
Q
population visibility analysis (PVA)
A
any systematic attempt to understand processes that make pop. vulnerable to extinction, technique used to measure minimum viable population
15
Q
4 interacting factors that might contribute to pop’s extinction
A
- demographic stochasticity
- =uncertainty resulting from random variation in reproductive success and survivorship at individual level
- environmental stochasiticity
- =random variations in components of habitat quality
- e.g. climate, nutrients, water
- catastrophes
- =dramatic events that occur at random intervals
- e.g. droughts, hurricanes
- genetic stochasticity
- random variation in gene frequencies of a pop. resulting from genetic drift, bottlenecks, inbreeding, etc.
16
Q
habitat degradation
A
process by which habitat quality for a given species is diminished
17
Q
habitat loss
A
habitat quality so low that environment is no longer usable by given species
18
Q
ecosystem degradation
A
alterations to an ecosystem degrade/destroy habitat for many of the species that constitute the ecosystem
19
Q
ecosystem loss
A
changes to ecosystem so profound to so many species (esp. dominant species) are lost so that ecosystem converted to another type (e.g. deforestation)
20
Q
contamination: air pollution
A
- extensive research on effects on human and domesticated species, less on wild species
- destroy plant species downwind from factories
- eradicate lichen species
- diminish individuals’ health and ability to reproduce
- can make aquatic habitats more acidic
21
Q
contamination: water pollution
A
- aquatic species more vulnerable than land species
- extinction of species in one place can lead to entire extinction b/c only found in one place
- less likely to cause extinction if in marine habitats
- eutrophication and harmful algal blooms
22
Q
contamination: pesticides
A
- some benign and break down quickly, others wreak havoc (e.g. DDT)
- biomagnification = pesticides concentrate at top of ecosystem
23
Q
human structures: roads
A
- curbs/lanes dividers absolute barriers to small, flightless mammals, etc.
- animals run down even if can cross
- provide access to habitats to people who want to exploit ecosystem
- may provide access for exotic species to infiltrate habitat
24
Q
human structures: dams
A
- limits species’ ability to move up/down stream during mating season
- e.g. salmon populations eliminated by dams
25
soil erosion
* natural process accelerated by humans (e.g. agriculture)
* leads to habitat degradation and decreased productivity of land
26
fire regimes
* severe human fires can destroy habitats
* campaigns to prevent fire also too effective - low intensity fires suppressed, leads to accumulation of fuel
27
water use
* mostly used for agriculture than industry, domestic uses and reservior expansion
* when remove large quantity of water, biota affected
28
deforestation
* forests grow in places w/ fertile soil so desireable for agriculture
* slowed, stopped or reversed in some areas
* demand for forest in developed countries decreased b/c pop stabilised or shift away from agro
* still issue in tropical regions
* damages diverse ecosystems
29
desertification
* grasslands/woodlands being degraded until dominated by sparse unproductive veg.
* usually associated w/ overgrazing and cultivation
30
why do large fragements have more species than small ones?
* greater variety of environments
* provides niches for additional species
* likely to have common and uncommon species
* small fragment likely to only have common species
* larger samples have more species
31
history of overexploitation
* humans killed off woolly mammoth 11000 years ago
* overkill (most important factor)
* climate change
* disease
* human-set fires
* Polynesians arrive in NZ and kill off bird species
* all types of moas
* Madagascar extinction
* giant tortoises
* giant lemurs (etc.)
* N.America by colonials
* nearly eradicated turkeys, beavers
32
what are the two major forms of overexploitation?
* bushmeat
* overfishing
33
overfishing
* not given enough public scrutiny
* not sympathetic to fish
* fishing happens in sea + not w/in national boundaries
* fish stocks only recently starting to decline
* fish population phenomena
* 'fishing down the food chain'
* predatory fish that used to dominate catches replaced by species further down food chain
* individual fisheries collapsing
* running out of new places to exploit (usually sustain total catch by fishing in remote and deep places)
34
bushmeat exploitation
* wild animal used for human food (esp. in tropical terrestrial ecosystems)
* profound effects
* loss of supply of protein
* exposure to HIV/AIDS and Ebola
* in W. Africa when have large fish supplies, lower bushmeat levels
* could be solved if Europeans stopped fishing off their coasts
35
commercial exploitation
why does this easily lead to over exploitation?
* huge potential markets for wild species
* enormous desire for wealth among exploiters
* domestic substitutes not identical to wild versions and therefore have lower prices
* market price of wild species increase as becomes rarer
* communal resources - costs shared among everyone
* wildlife found in remote places (lesser legal grip)
* exploiters have capital to purchase tech to gather wildlife in large quantities
* disparity in currencies makes selling rare species profitable
36
recreational exploitation
* examples
* hunters
* watchers
* anglers
* pros/cons
* bad b/c leads to overexploitation
* good b/c licenses fund conservation efforts
* even nonconsumptive exploitation can be harmful to animals b/c shy, etc.
37
incidental exploitation
* e.g. catching tuna w/ nets and drowning dolphins in process
* most destructive is trawling for shrimp
* killed turtles but now must have devices on trawlers to release turtles
38
indirect exploitation
e.g. roads, fences, etc.
39
consequences of overexploitation
* effects on large species worse b/c larger = more babies
* tend to hunt animals in reproductive prime or growth prime (i.e. cutting down trees) not at natural mortality
* tend to kill males more b/c larger and travel more therefore more contact w/people
* skewed pop can affect reproduction
* not worst b/c most males mate w/ many females (polygynous)
* can change genetic structure - kill best and leave worst
* change landscapes (cut down trees, no longer forest)
