B4.2 Ecological niches

niche

the unique role of a species in an ecosystem

low temp adaptation in oak and maple trees

• they live in very cold climates often

• synthesize special “anti-freeze” proteins which prevent the formation of crystal inside the cells

• enable species to survive in temps as low as -40º

• these species cannot survive at high temps

biotic factors affecting species

• human

• competitors

• predators

• parasites

abiotic factors affecting species

• water

• temperature

• food supply

• soil pH

• mineral/nutrient availability

spatial habitat

the physical area inhabited by any particular organism

tolerance

how well a species reacts to something in its environment

obligate anaerobes

single celled organisms that have no tolerance for oxygen. They die of they come in contact with oxygen. they live in deep soil and water where no oxygen can reach them

facultative anaerobes

organisms that can carry out both aerobic and anaerobic respiration, depending on wether there is oxygen present. yeast is an example

obligate aerobes

need oxygen to convert food nutrients in to energy. If levels of O2 drop too low or there are non, the organism dies

autotrophs

organisms that can make their own food from inorganic substances using techniques such as photosynthesis

heterotrophs

organisms that cannot make their own food but rely on eating other organisms for food

holozoic nutrition

food is absorbed, digested internally, absorbed, and assimilated

consumers

organisms that obtain their organic molecules through eating other organisms

mixotrophic nutrition

organisms that are both heterotrophs and autotrophs

example of a mixotroph

euglena. they are single celled and have both photosynthetic pigments and can ingest food from the water around them

obligate mixotroph

organisms that need both autotrophic and heterotrophic systems to grown and survive

facultative mixotrophs

can survive on one system but they use the other as a supplement

saprotrophs

• live on or in non-living organic matter

• they secrete digestive enzymes onto the organic matter and absorb the products of digestion

why are saprotrophs important

they facilitate the breakdown of organic material.

decomposers

fungi and bacteria that facilitate the decay of organisms

archaea

one of the three domains of life

modes of nutrition used by archaea

• photosynthesis

• chemosynthesis

• heterotrophic nutrition

chemosynthesis

generating cellular energy from reactions involving inorganic molecules without the help of sunlight

why are teeth fossils important

these fossils tell us a lot about one’s diet and what niche they could have occupied based on that diet

incisors

• the front teeth

• used for cutting

• present in meat eaters

canines

• the pointy teeth next to the incisors

• used for tearing

• present in meat eaters

premolars

• the first of the 3 back teeth

• used for grinding

• present in vegetarians

molars

• the back teeth

• used for grinding

• more pointy are adapted for meat

• more flat adapted for plants

herbivores

animals that eat a plant based diet (ie. they feed on producers) eg. zebras, deer

carnivores

meat eaters. feed on other consumers. eg. lions, snakes

teeth and herbivores

• large incisors

• wide premolars

• used for shearing and crushing plant

carnivores and teeth

• pointy teeth

• premolars are narrow and pointy

omnivores and teeth

• their teeth are somewhere between those of carnivores and herbivores

• not very pointy

• there premolars are rounded but not flat

omnivores

eat both meat and plants

chimpanzees and teeth

• small incisors and pointed canines for eating meat

orangutang and teeth

• long canines despite not eating meat

• they are there for intimidating predators

adaptations of plants against herbivory

• thick barks

• thorns and spikes

• chemical irritants (like stinging nettle)

• phytotoxins

animals and phytotoxins

• ruminants have bacteria in their gut that detoxify the toxins

• in other mammals, the liver can detoxify small amounts of the toxin

adaptations of herbivores to eat plants

• the small bugs aphids, they have a mouth part that acts like a needle that pierces the bark to immediately drink the sugar inside the sap

• cows and sheep have special back teeth that are broad to better grind plants

• ruminants chew their food again and again in order to break down the cellulose to a smaller size for digestion

• bacteria in the stomach of ruminants also helps in breaking down cellulose

chemical adaptations to catch prey

• injecting neurotoxins that paralyse prey (eg snake venom)

• some species are able to replicate pheromones to trick their prey

physical adaptations for catching prey

• sharp claws and teeth to disable prey

• echolocation used by bats and dolphins

• acute sense of smell

• excellent eyesight in birds

behavioural adaptations to catch prey

• hunting in packs

• ambush predaturs and tiring out prey (cheetahs)

chemical adaptations to resist predation

• prey can produce bad tasting chemicals

• can produce poisonous chemicals (eg poison dart frog)

physical adaptations to resist predation

• camouflage

• bright colors used as warning that they are poisonous

• mimicking more dangerous animals

• spines and shells

behavioural adaptation to resist herbivory

• herding

• hiding

adaptations of trees to harvest light

• positioning leaves high above ground so they are above competitors

lianas

• borrow support from nearby tress

• lianas are vines

• the seedlings grow towards the trees to they can climb up them as they grow

• they can eventually kill a tree

epiphytes

• grow on the tree trunks and grow like moss on leaves

• survive on very little water that trickles down from leaves

hemi-epiphytes

• half their lives are without roots on the ground, the other half their roots grow and reach the gorund

plants growing the shade

• mostly herbs

• absorb longer wavelength of light to survive

fundamental niche

the potential niche it could inhabit given the adaptation of the species and its tolerance limits

realized niche

the actual niche a species inhabits

principle of competitive exclusion

• no 2 species in a community can occupy the same niche for a long time

• if they do the numbers of both populations will both decrease

• in the long run, one species will replace the other

• the less adapted species will day and the more adapted will survive

interspecific competition

competition between 2 or more species for the same resources