Unit 8: Ecosystems - Stability, Change and Conservation Flashcards
what is evolution
change in the heritable characteristics of a population
what is lamarckism
acquired traits can be passed down to offspring
–> now FALSIFIED
evidence for evolution
DNA –> RNA –> Proteins
Evidence =
1. new sequences arise and some become more common
2. some genes are common to many species
3. genes in closely related species are more similar
evidence for evolution from selective breeding of domesticated animals and crop plants
(artificial selection) selective breeding –> domestication of crop plants and animals
—-> control reproduction, control offspring so that desirable traits become more common
evidence for evolution from homologous series
homologous series = same structure
what is a stable ecosystem
can persist for a very long period of time
what are the requirements for a stability in an ecosystem
stability depends on:
- nutrient cycling
- constant energy supply
- genetic variation within a species
- stable climate
disruptions include:
- removal of materials/species
- eutrophication
- climate change
what is a tipping point
reaching a level of disturbance that causes quick change that is difficult to reverse
(i.e. amazon rainforest: deforestation = fewer trees = less transpiration = drought
= fires)
positive feedback loop
what is a model that can be used to investigate the effect of variables on ecosystem stability
mesocosm
adv: replicates, easy, control factors
disadv: impossible to replicate all natural factors
what is a keystone species
an organism that has a disproportionate effect in a community (i.e. removal will make it likely that the entire ecosystem will collapse)
what is sustainable harvesting
replacement rate must be > or = to harvesting rate
i.e. cod
-> protected breeding zones
-> increase net hole size
-> set harvesting limits
-> monitor populations
what are the factors that affect the sustainability of agriculture
consider the following:
-> soil erosion (tilling causes soil loss)
-> fertilisers leach into bodies of water (causes eutrophication)
-> pollutants (pesticides)
-> carbon footprint (from energy/fuels)
explain eutrophication
nitrogen and phosphorus rich fertilisers on land run off into bodies of water
algae bloom on surface blocks sunlight and kills bottom plants
deecomposition of plants consumes all of the oxygen, increases biological oxygen demand, killing other marine life
explain biomagnification of pollutants in natural ecosystems
bioaccumulation - increase toxin levels throughout an organisms life
biomagnification - increase toxin levels throughout trophic levels
–> higher trophic levels higher toxin levels
toxin examples: mercury and DDT
what are the effects of microplastic and macroplastic pollution of the oceans
plastic waste accumulates because it doesn’t break down, can release toxic compounds
macroplastic = large visible waste
–> ingestion by marine life
–> entanglement
microplastic = small fragments from the degradation of large pieces
–> found EVERYWHERE
–> in animal tissues
–> effect TBD
what is rewilding and what does it do?
rewilding = remove effects of human intervention to allow natural processes to restore ecosystems
can do this by:
- stop human activities
- reintroduce species
- distributing seeds of plants that should occur there
- control invasive species
- reconnect habitats
example: Hinewai Reserve in NZ
shift from farmland to native forest by reducing effect of human intervention
describe ecological succession and its causes
ecological succession = biotic and abiotic changes that transform an ecosystem
what is primary succession
succession starting w an environment w few living organisms
(like bare rocks, bacteria, lichens cause erosion, soil development, shrubs, trees
what are the changes that happen during primary succession
increase in…
- primary production
- species diversity
- food web complexity
- nutrient cycling
what cyclical succession
patterns of change and succession that occur either naturally or due to periodic disturbances
i.e. = oak forest –> grassland –> oak forest
no stable climax community
what is a climax community
a stable, relatively unchanging ecosystem
what is a plagioclimax
alternative climax community that results from human activity
i.e.
grazing
-protected, artificially high population of livestock
-grasses persist
-no succession by shrubs or trees
wetland drainage
-swamps and bogs are natural carbon sinks
-waterlogged and anoxic, special adaptations
-drainage causes other plants to thrive
what is arrested succession
ecosystem permanently halted in an early successional, typically non forested state
normal vs enhanced greenhouse effect
normal = good
- keeps earth warm
enhanced = bad
- thickening of greenhouse gases-BADDD
positive feedback cycles in global warming
- less snow –> less sunlight reflection –> more radiation absorbed –> more ice melting
- more heat –> more permafrost –> more decay and more methane
- warmer oceans –> less dissolved co2 –> more co2 in atmosphere –> more heat
- warmer temps –> more drought more fires –> more carbon release
explain an example of polar habitat change
emperor penguins
use ice for breeding
distance to/from sea is important
early icebreak can kill chicks
walruses
use ice for resting
lack of ice –> energy expenditure finding ice
explain how changes in ocean currents alter the timing and extent of nutrient upwelling
warmer surface water decreases ocean currents, leading to stratification (stable layers instead of mixing)
less current also leads to less upwelling of nutrients and altered timing, reducing nutrient cycling and primary production and energy flow
explain poleward and upslope range shifts of temperate species
UPSLOPE
animals live at top of mountain
only them because niches
if warmer, species move upslope to find optimal temp
compete for niches with species already living up there
POLEWARD
same as before, but instead of up, they move to the poles
what are the threats to coral reefs
co2 absorption causes water to become acidic
more difficult for corals to absorb carbon from water
calcium carbonate shells of marine organisms dissolve
warm water also causes coral to expel mutualistic algae (bleaching)
thus, coral reef ecosystem collapses
what is carbon sequestration
capturing and storing carbon (making a carbon sink)
–> photosynthesis
–> plant growth
–> building of shells of marine organisms
–> fossilisation and peat formation
what is afforestation
planting trees in areas w/ no trees
what is forest regeneration
planting trees that have been cut down
adv and disadv of afforestation/forest regeneration
usually fast growing species that do not occur naturally
adv:
positively affects carbon sequestration
disadv:
monoculture
may have neg. impacts on other factors that affect ecosystem stability
describe peat forming wetlands restoration
peat = partially decomposed organic matter trapped under acidic, waterlogged soil (anoxic)
can happen quickly in tropical environments
restoring previously drained wetlands and reintroducing native species helps reestablish these areas as carbon sinks
what is phenology
study of seasonal timing of event in plants and animals
changes in timing can indicate climate change
2 major factors: temp and photoperiod (daylight hours)
what are some events affected by the 2 major factors of phenology
temp:
bud burst (new leaves)
photoperiodism
bud set (growth stoppage)
flowering (short day vs long day plants)
bird migration
explain the disruption to the synchrony of phenological events by climate change
Temps are changing
Two interacting species need to synch their timing
if one is cued by photoperiods, and another by temps
a disruption in temp may throw off the timing of events necessary for successful interaction
i.e. caribou eat arctic mouse ear and time their spring migration to match the peak development of the arctic mouse ear
-mismatch between migration timing and plant development-> not enough food supply
i.e.2 great tit eat caterpillars
need lots of food during breeding season
caterpillar population peak earlier due to warmer weathers
great tit breeding season stayed the same
fewer surviving chicks
explain the increases to the number of insect life cycles within a year due to climate change
spruce bark beetle (pest)
-develops in weak trees
-healthy trees limit spruce bark beetle population
-drought and warm temps stress trees
-more spruce bark beetles
2 year generation time has reduced to 1
trees are now more susceptible and there are more beetles
explain evolution as a consequence of climate change
tawny owl
-overpopulation and competition = food shortage
-variation = feather colour (gray vs brown)
- survival of the fittest (less snow cover changes the ability to blend in)
- increase in trait frequency = brown colour more common
what are the different types of diversity
ecosystem
varied environments and species (i.e desert vs coral reef)
species
many diff species (i.e. fungus vs polar bear)
genetic
gene pool within species vary (poodle vs great dane)
now vs then: number of species on earth
many more now than then
causes of anthropogenic species extinction
- overharvesting
- habitat destructions
- invasive species
- pollution
- global climate change
causes of ecosystem loss
- land use for agriculture
- urbanisation
- overexploiting resources
- mining
- dams and water extraction
- diversion of water
- fertilisers and eutrophication
- climate change
evidence for a biodiversity crisis
biodiversity crisis: unprecendented loss of ecosystems, species, and genetic diversity
- population sizes
- ranges
- species diversity in an ecosystem
- richness and evenness
- area
- degradation extent
etc etc
simpson’s diversity index:
D = diversity index
N = total number of organisms in all species
n = total number of individuals in a specific species
D = (N(N-1))/(∑(n(n-1)))
high index when you have a high richness and evenness of species
causes of the current biodiversity crisis
overpopulation
need for several approaches to conservation of biodiversity
in situ: conservation in the natural environment
- no disruption to behaviour/evolution
-cost-effective
-active management
ex situ: outside the natural habitat
- captive breeding and release
- preservation of endangered species
- preservation of eggs/sperm/seeds
selection of evolutionarily distinct and globally endangered species for conservation prioritisation in the EDGE of Existence programme
you cannot save them all
EDGE of existence prioritises conservation efforts based on
- uniqueness
- likelihood of extinction)
