IB Bio ecological niches

niche definition and things that make up a niche

definition- The role of a species within its habitat

• The role of a species includes

  • What it eats

  • Which other species depend on it for food

  • What time of day a species is active

  • Exactly where in a habitat a species lives and feeds

  • The abiotic factors acting on a species

  • The biotic factors acting on a species

why can no two species fill the same niche within a habitat

they will be in direct competition and eventually outcompete one another

even if it seems like species are occupying the same niche, there will be subtle differences in their role e.g. they have different feeding locations or times throughout the day

obligate anaerobes+ examples

can only respire anaerobically

they cant tolerate oxygen

e.g. early bacteria due to the lack of O2 in the atmosphere ages ago

the only ones now are found in deep soil or water

facultative anaerobes and examples

mainly respire aerobically but can switch to anaerobic

e.g. brewers yeast or E Coli

obligate aerobes and examples

These organisms cannot survive in the absence of oxygen; they rely on aerobic respiration to release energy from food

• They may be able to carry out anaerobic respiration in some cells for short periods, but they cannot survive on anaerobic respiration alone

e.g. most animals, most fungi except yeast, bacteria like mycobacterium tuberculosis

what is ATP and where does it come from

it is energy which is stored in the form of ATP

organisms need this to survive

the energy stored in ATP comes from carbohydrates and is transferred during respiration

method/ mode of nutrition definition

the way by which an organisms gains its organic molecules to fuel respiration

2 modes of nutrition and how they work

autotroph- produces its own organic molecules from inorganic substances in its environment

heterotroph- gains organic molecules from the tissues of other organisms

photoautotrophs and chemoautotrophs

photoautotrophs are organisms that use light energy

chemo are organisms that se energy from the oxidation of chemicals

examples of photosynthetic organisms (photoautotrophs)

examples of photosynthetic organisms aka producers are:

plants (terrestrial and aquatic)

algae (single cellular and multicellular seaweeds)

photosynthetic bacteria like cyanobacteria

how do photoautotrophs produce their own food

they use light energy to convert CO2 into organic molecules like carbohydrates

their pigments like chlorophyll absorb the light energy, enabling this process

the light energy is transferred into chemical energy

holozoic nutrition

definition- involves internal digestion

organisms that use holozoic nutrition are heterotrophs who ingest, digest, absorb and then assimilate molecules from the tissues of other cells

ingest= eat

digest= break down larger molecules into smaller ones

absorb= the transport of molecules from digestive tract into cells

assimilation- using molecules to build cells

mixotrophs

these are organisms which are able to make use of more than one mode of nutrition, such as auto and heterotrophy

examples include

corals

marine plankton

carnivorous plants

obligate mixotrophs

• Obligate mixotrophs must constantly have access to both methods of nutrition

Facultative mixotroph

• Facultative mixotrophs can survive using one method of nutrition, which is supplemented by the other

saprotrophs and examples

these are heterotrophs which externally digest their food by secreting an enzyme onto it before absorbing the products of this digestion

examples are fungi and bacteria (decomposers)

how do saprotrophs work and what products do they produce before absorption

Saprotrophs secrete a wide range of digestive enzymes that allow them to hydrolyse a large variety of biological molecules, and so to release a large range of products.

Examples of these products include mineral ions, such as ammonium ions and phosphate ions

do saprotrophs absorb all of the products that are released during hydrolysis

no, some minerals are left behind in the surrounding soil for absorption by other organisms such as plants

why are saprotrophs important?

without them, all of the locked up nutrients in dead matter would never be released and plants wouldn’t be able to absorb enough minerals

archaea definition

a diverse group of single celled organisms which make up one of the 3 domains

they can be phototrophic, chemotrophic and heterotrophic

phototrophic archaea

use energy from light to generate ATP

chemoautotrophic archaea

they produce ATP by chemosynthesis:

1. energy is released from chemicals in the environment

2. this energy is transferred to carbon compounds

3. these carbon compounds are used for ATP production

examples of chemicals in the environment which can act as energy sources for chemosynthetic archaea

hydrogen gas

ammonia

methane

hydrogen sulphide

chemoheterotrophs (archaea)

these use chemicals to produce ATP but they gain their carbon compounds from other organisms, they dont produce them

heterotrophic archaea

gain their carbon compounds from other organisms and then use these carbon compounds to generate ATP

adaptation definition

traits that aid an organisms survival to its environment

adaptations for herbivory in insects and mammals

insects:

aphids have specialised mouthparts called stylets which allow them to pierce plant tissues and reach sugary sap inside the phloem

caterpillars and other insects have mouthparts called mandibles which allow them to cut through leaves

mammals:

they have the ability to neutralise the toxins produced by plants

they may have flat teeth for grinding plants

ruminant mammals are able to regurgitate and re-chew their food

example of a mixotroph

euglena is a freshwater protist which is both auto and heterotrophic.

plant adaptations against herbivory

mechanical deterrents:

-cacti have sharp spines

-nettles have hairs which contain toxins and irritate the skin

-thick nark prevents aphids piercing stems

toxic compounds:

-foxgloves produce digitalis which affects the heartbeats of humans and animals

-many plants produce tannins which deter herbivores by their bitter taste

types of predator/ prey adaptations

chemical

physical (features)

behavioural

chemical predator adaptations

snakes, scorpions and spiders produce venom

-this either damages the circulatory system or interferes with nerve impulses

chemical mimicry attracts prey

physical predator adaptations

either sense organs:

birds of prey have great vision

predators have eyes at the front of the skull for good perception of distance

or body structures:

swordfish are streamlined so can swim fast

cheetahs have long limbs so can run fast

behavioural predator adaptations

crocodiles approach their prey from underwater before bursting out of the water at high speed

pack predators increase their chance of success by working together

chemical prey adaptations

some prey animals produce toxins that deter predators like skunks producing unpleasant smells

poison dart frogs produce toxins in their skin

physical prey adaptations

camouflage

mimicry such as owl butterflies who have wings that look like owl eyes

turtle shells

spines in hedgehogs and porcupines

behavioural prey adaptations

rabbits run to their burrows when they sense a predator

grouping together

warning calls to others in the group

pretending to be dead (bluffing)

plant adaptations for harvesting light

trees that grow to the upper canopy are called emergent trees and gain the most sunlight

lianas- woody vines that grow around tree trunks to reach sunlight at the canopy. they get their nutrients from their roots in the soil

epiphytes- similar to lianas, but they grow around tree branches and don’t begin their lives on the forest floor, instead get their nutrients from the canopy

strangler epiphytes- same as above but grow roots down to the floor so gain nutrients and water from the soil

shade tolerant shrubs and herbs- grow on the forest floor and are adapted to absorb limited range of light wavelengths that reach the understory. they contain different photosynthetic pigments allowing them to absorb other light wavelengths. they have large leaves to maximise surface rea

fundamental niche

the potential and full range of conditions in which a species could survive and reproduce, based on is adaptations and tolerance limits

realised niche

the actual conditions and resources in which a species exists, due to biotic interactions and competition

competitive exclusion and its results

when a species is eliminated from its niche due to competition with another species in the same niche.

its either forced to occupy a slightly different niche

or is made locally extinct