B4.2 Ecological Niches

Niche

Ecological niche: The role a species plays in its ecosystem

What niche an organism can fill depends on:

• How it obtains food (specialisation reduces competition)

• Zones of tolerance (range determines habitat)

• How it interacts with other species In the ecosystem

Fundamental vs Realised niche

Fundamental niche: Potential niche species could occupy with no competition

Realised niche: Actual niche a species occupies in presence of its competitors - range of tolerance is occupied by competitors

E.g. Chthamalus barnacles

• Fundamental: low tide + high tide

• Realised: Only high tide due to competition with Semibalanus barnacles.

Competitive exclusion

• When fundamental niches of 2 species overlap causes competition

• Which can lead to one species outcompeting the other, resulting in the exclusion of the less competitive species from that niche.

  • Only if the non competing species is outcompeted in all parts of its fundamental niche

• Weaker species is eliminated

• E.g. 2 species of protozoans

  • Paramecium aurelia + Paramecium caudatum

  • aurelia survived and outcompeted caudatum

Niche partitioning

• The process by which competing species in fundamental niche coexist

• By utilising different resources or habitats to reduce competition

• Allowing them to occupy the same area without directly competing for the same resources

• Both become restricted to just part of fundamental niche

• E.g. Warbler birds inhabiting particular part of same tree

• E.g. Shore birds that share area on shore

Obligate Anaerobes, facultative anaerobes, + obligate anaerobes

• Anaerobes survive in environments with no air/oxygen - eutrophication, polluted lake/soil

• Aerobes require oxygen to survive and thrive in oxygen-rich environments, such as the atmosphere.

• Organisms can be placed into 3 categories

  • Facultative anaerobes - can survive in either oxic (aerobic) or anoxic (anaerobic) environments

    • E.g. E. coli, yeast

  • Obligate aerobes - must have oxygen = all animals + plants

    • E.g. humans, most animals

  • Obligate anaerobes - cannot survive in oxygen

    • E.g. Clostridium species

Autotrophic nutrition

• Photosynthesis is the mode of nutrition in plants, algae + several groups of photosynthetic prokaryotes

• Produce own organic compounds from inorganic (self-feeding) - through photosynthesis or chemosynthesis.

  • Plants, algae, some bacteria

• Organisms such as plants and some bacteria that convert sunlight or chemical energy into food, forming the base of the food chain

  • Photosynthetic prokaryotes (Cyanobacteria) even tho there aren’t any organelles the whole thing is like a chloroplast

Adaptations of plants for harvesting light

• Lianas (type of plant): Climbs to the top by using other plants - top has more light

• Epiphytes: Germinate high up (not rooted in soil), grow on other plants, gaining access to sunlight without harming their host, get nutrients and water from air/moisture/host branch

  • not parasites but need a host plant

• Strangler epiphytes: Start same as epiphytes BUT grow long roots down, gradually enveloping it and competing for light, eventually outcompete the host--killing it.

• Shade tolerant shrubs/herbs: These plants can thrive in low-light conditions, adapting their leaf structure and photosynthetic efficiency to maximize light capture in shaded environments.

• Trees grow very tall so no competition of light - Yellow Meranti

Heterotrophic nutrition

• Obtain organic compounds from other compounds (feed on others)

  • All animals + All fungi

• Includes:

  • Holozoic - whole pieces of food eaten + digested internally (ingest food, digest (chemical breakdown into smaller molecules, absorption (of some of smaller molecules) assimilate (incorporate into new material), egestion (leave as waste))

    • Amoeba, Humans

  • Saprotrophic - type of decomposer that digests matter externally (don’t ingest, release enzymes onto food to digest and absorb the digested food)

    • Fungi + bacteria

      • Detrivitores: digest matter internally - holozoic nutrition

Mixotrophic nutrition

• Organisms can obtain energy and nutrients through both autotrophic and heterotrophic means, such as some protists and plants.

• This allows them to adapt to varying environmental conditions.

• E.g. Euglena is a freshwater example - facultative mixotroph

• Obligate mixotroph: must use both methods

• Facultative mixotrophs: can use one method or other depending on what is available in the environment

Diversity of nutrition in archaea

• Archaea: one of three domains of life

• Archaea are very diverse with many methods of nutrition

• Main methods

  • Phototrophic: absorption of light energy

  • Chemoautotrophic: oxidation of inorganic chemical substances to obtain energy (Fe2+—>Fe3+)

  • Heterotrophic: Obtain organic compounds from other compounds (feed on others)

Adaptations of herbivores for feeding on plants and of plants for resisting herbivore

Herbivore: Organisms that primarily consume plants or plant-based materials for energy and nutrients, playing a key role in the food chain.

• Adaptations of herbivores: Leaf eating insects - E.g. Aphid Insect

  • Chewing mouth part (mandibles)

  • Piercing mouth part (Stylets) used to suck up sap from phloem

• Adaptations of plants for resisting herbivore (being eaten by herbivores)

  • Spines/spikes

  • Stinging parts

  • Toxins (poisoners or just stingers)

• Some herbivores have adaptations for overcoming these adaptations ^^^

  • Some aphids produce saliva that acts like a barrier + protects it from plant toxin

Omnivores

Organisms that consume both plants and animals for energy and nutrients, contributing to various trophic levels in ecosystems.

Carnivores

Organisms that primarily consume other animals for energy and nutrients, often serving as predators in the food chain.

Adaptations of predators for finding, catching and killing prey and of prey animals for resisting predation

Predators: Organisms that hunt and kill other animals for food, playing a crucial role in controlling prey populations and maintaining ecosystem balance.

• Not all carnivores are predators - vultures do not kill

Adaptations of predators for catching prey

• Physical: Stealth + speed, eagle spot prey from 3km away, Owl hears everything even tiny movements by mouth, teeth/claws in lion

• Chemical: Cone snail injects venom

• Behavioural: Dolphins hunt in packs

Adaptations to resist predation - some adaptations develop more quickly than others (behavioural is fastest - chemical is slowest)

• Chemical: Monarch butterflies produce toxin that kills predator, skunk spray is a pungent liquid from anal glands

• Physical: Walking stick bug camouflage

• Behaviour: mackerel fish school together and seem larger to avoid predation

Prey

Organisms that are hunted and consumed by predators, playing a vital role in food webs and ecosystem dynamics.

Relationship between dentition (teeth) + diet of omnivorous + herbivorous members of family hominidae

For extinct species we can figure out what they were by: By examining their fossilised teeth and jaw structures, scientists can infer dietary habits and classify them as herbivores, carnivores, or omnivores.

• Hominidae: family that includes humans, orangutans, chimpanzees, + gorillas

• Shape of teeth = indicators of what they eat

• Carnivore: sharp teeth adapted for tearing flesh - sharp canine incisors

• Herbivore: flat teeth designed for grinding plants

• Omnivore: a combination of sharp and flat teeth for consuming both plants and animals.