IB Biology Hl: all ecology-related case studies

just all of them. some flashcards are repeats from other decks

adaptations of maram grass - sand dunes

• high resistance

• fine, narrow leaves resisting strong winds and sandblasting

• thick outer layer of waxy cuticle resists water loss

• rolled leaves reduce SA for evaporation, conserving water

• hairs inn the inner leaf epidermis reduce evaporation and air flow over the stomata to tolerate dessication

• sunken stomata and rolled leaves decrease the humidity gradient and reduce water loss

• extensive root systel allows for coping with moving sand and low nitrate in top soil

Rhizophora apiculata adaptation - mangroves

• stilt roots; gives structural integrity

• halophyte; can survive in salty water

• specialised roots; pneumatocytes; they respire even in waterlogged soil

• seeds start to germinate while still attached to parent plant

Coral reef conditions

• warm water (23-28)

• sunlight for zooxanthellae

• salt water; won’t growth at mouth of rivers

• clear water; so no farming/freshwater treatment. no sediment

• moderate wave action; not too strong

• need inundation

• alkaline water ( like ph8 )

rainforest conditions

• high precipitation ( 1500-2000mm )

• high temperatures

• low sunlight

• low seasonal variation

conditions of grasslands

• low to moderate temperature ( 10-25 C° )

• low to moderate precipitation (250-1000m)

• high light intensity

• high seasonal variation

conditions of taiga

• low temperatures ( -20 - 10 C° )

• moderate rainfall

• high seasonal variability

conditions of temperate biome

• moderate temp ( 20C°)

• moderate to high rainfall ( 500-1500mm )

• moderate light intensity

• moderate seasonal variation

conditions tundra

• low temperatures ( -30 - 10 )

• low rainfall

• moderate to high light intensity

• high seasonal variability

conditions desert

• high temperature

• low precipitation

• high light intensity

• low seasonal variation

plant adapted to desert example

• ocotillo

• deep root system which allows access to water deeper down, and extensive shallow root system to absorb as much water as possible during rainfall

• chlorophill containing bark allows it to perform photosynthesis

• no leaves as water would be lost by evapotranspiration

• thorny stems expand to store water during rainfall and deter herbivores

• small leaves sprout after rainfall to perform photosynthesis

• bright red flowers to attract pollinators

animal adapted for desert example

• gila monster

• fat storage in tail

• bumpy scales on skin allows to retain moisture

• slow metabolic rate allows to go long time without water

• venomous saliva; for predators and prey

plant adapted for rainforest

• giant water lilly

• giant waxy leaves with 3M of diamater; wax is hydrophobic, allows to float

• large flower with strong fragrance attracts pollinators

• root system which allows to anchor to soil of lake and absorb nutrients

animals adapted for rainforest

• orchid mantis

• female looks like orchid, which attracts pollinators

• example of mimicry

• male is small and plain, allowing it to camouflage in the tree

allelopathy in plants - example

the black walnut tree produces juglone into the soil, which inhibits root development and photosynthesis in nearby plants.

allelopathy of microbes

penicillin ( the funghi ), produces penicillin, which kills bacteria by blocking bacterial enzymes needed for cell wall formation

streptomycin (bacteria ): secretes streptomycin into the soil, to suppress other bacteria to not have to compete with other bacteria

exampleS of stable ecosystems

• tropical rainforests; despite natural disasters, number of species remains relatively constant, but recovery is slow

• coral reefs

• borea forests/ taiga; withstand cold, long winders, many coniferous trees

• Deserts; despite year long heat, species survive

trophic cascade example

• sea otters prey on sea urchins and control population size

• if sea otters die, sea urchins can reproduce unhindered, population boom ensures

• sea urchins overgraze kelp forest, which is bad as kelp forests are carbon sinks

• other organisms dependent on kelp for habitat are negatively affected

keystone species effect

beavers; create dams, which alter flow, which create new habitats for species = new niches. if they disappear, the habitats the created and species dependent on them are endangered. plus, droughts can appear as water storage abilities of ecosystem are hindered

yellowstone wolves case study

• wolves were hunted to extinction

• elk population increases, tree species such as aspen and cottonwood suffered from overgrazing

• plant diversity lowered, and land erosion increased

• elk control prevented further degradation but didn’t improve condition

Rewilding/ restoration case study - Hinewai Reserve, New Zealand

• used to be farmland, but is now privately owned

• initial intervention: removal of non native species

• now minimal human intervention = > native species are restored by succession

cyclical succession example

pasture to forest

• conditions temporarily change (less water, unideal temps) and tree dies

• open pasture is created

• herbivores eat the seeds and shrubs (baby trees) making it hard for forest to redevelop

• when grazers become less active, shrubs begin to dominate as they have the opportunity to grow - spiny, so grazers don’t eat them

• tree seedlings start to grow as they have sheltered by shrubs

• tree matures

primary succession case study

Iceland surtsey island, created in 1960 - now mid succession, not yet climax community ( no trees )

teeth

• require large masseter muscles connecting to the skull

• need a lot of muscles to chew the leaves with waxy cuticles

• lateral movement of mandible

and teeth stuff

alien invasive species case study

grey squirrel introduced from US

• greater reproductive rates

• carry squirrelpox

• can digest acorns quicker+ more efficiently

• bad as outcompetes local and causes more bark stripping damage

mutualism example

• root nodules in fabacea ( legumes ) - nitrogen fixing bacteria, nitrogen to ammonia to nitrates, can be used for amino acid synthesis. good for bacteria as get carbs

• mycorrhyzae in ochidacerae; orchids cannot photosynthesise, gets nutrients

• zooxanthelle and corals: zoo gets refuge from coral, coral gets nutrients from zoo’s photosynthesis

parazitism

• fleas feed on mammals blood

• mistletoe growths on branches of trees, taking their nutrients

example of food web ( use your few iq points and turn it into a pyramid if needed )

example of chemotroph

iron oxidative bacteria

ecosystem loss 2 case studies

mixed dipterocarp forest southeast asia

• deforestation for palm tree expansion and for high value timber

• reduced carbon storage capacity

• reduced frugivore population: orangutans

aral sea

• 1960’s soviet irrigation system for cotton plantation

• by now from 4th largest lake, lost 90% of it’s coverage

• now very salty, most fish population destroyed

• loss of wetland habitat, reducing biodiversity (birds)

population growth curve

24 rabbits released in Australia in 19th century

• no natural predators and abundant food source

• up to 6 litters a years, increase pop exponentially, 100km a year

• overgrazing/ habitat degradation and intraspecic competition increases

• by beggining of 20th century population stabilises at a high number

3 examples of human extinction

• new zealand north island giant Moa - giant flightless bird hunted to extinction by humans when they arrived in 1300

• carribean monk seals - existed in the gulf of mexico, declared extint in 2008, easy to hunt for oil and meat by european colonisers as docile

• passenger pigeon, endemic to north america, excessive hunting and loss of habitat + very social nature, requires a high population, lead to it’s exctinction in the wild in 1895