Biology - B4.2 Ecological niches

Definition ecological niche

Describes the role of a species in an ecosystem

E.g. habitat, resource utilisation, interactions with other organisms

Definition fundamental niche

Potential range of conditions a species can tolerate

Definition realised niche

Actual conditions where a species exists due to competition

Comparing fundamental vs realised niche

Where the species actually lives is smaller than the fundamental niche because a competitor inhibits some of it

Definition competitive exclusion

When 2 species are occupying the same niche and there are limited resources. Therefore, one species outcompetes another species.

The species cannot co-exist indefinitely and occupy the same niche. Therefore, one is excluded (die out or live on periphery and move out) or both adapt.

Leads to unique niche

Definition exclusion

The species dies out or lives on the periphery and moves out

Types of competitive exclusion

Intraspecies and interspecies

Definition intraspecies competitive exclusion

Same species are competing for the same space, one is excluded or both adapt

Definition interspecies competitive exclusion

Different species are competing for the same space because they have the same diet and prey

Niche partitioning

Process where competing species use different resources or the same resource in different ways to reduce competition and coexist

Anaerobes and aerobes

Groups of organisms by their type of nutrition

Definition obligate aerobes

Organisms that require a continuous supply of oxygen, mostly perform aerobic respiration (e.g. all animals and plants)

Definition obligate anaerobes

Organisms that are killed by oxygen and require anaerobic environment (e.g. methanogenic archaea)

Facultative anaerobes

Organisms that can live in either environment (e.g. E coli and yeast)

Definition autotrophic nutrition

Self-feeding organisms that use external energy

For example plants that perform photosynthesis and inorganic molecules to make organic molecules for energy

Adaptations of plants for harvesting light

Plants in forests use different strategies to reach light sources quickly or simply tolerate lower light conditions. Its crucial because photosynthetic autotrophs rely on light for their nutrition.

E.g. lianas, epiphytes, strangler epiphytes and shade tolerant shrubs and herbs

Adaptations of lianas for harvesting light

• Climb other trees to get to the top of the canopy

• The plant uses other trees to grow quicker than other competitors

Adaptations of epiphytes for harvesting light

• Gains nutrients from tree branches or air/moisture

• Also has trees for structural support and to get to upper canopy

Adaptations of strangler epiphytes to harvest light

• Are like the normal epiphytes but roots in the soil, climb trees to get to upper canopy

• Eventually kills host tree

Adaptations of shade tolerant shrubs and herbs to harvest light

• Have adapted to grow in low light on the forest floor

Definition heterotrophic nutrition

Organisms that feed on others,

Get energy from organic molecules through consumption of other molecules

Types of heterotrophic nutrition / dif consumption methods

Holozoic nutrition (ingestion, digestion, absorption, and egestion)

Saprotrophic nutrition (break down dead organic matter by external digestion, secretes enzymes into environment to digest dead organic matter)

Mixotrophic nutrition

Organisms can be both autotrophic (self-feeding) and heterotrophic (feeding on others), digest in anyway, have adapted to this nutrition type because usually live in unstable environments

e.g. protists

Nutrition types of archaea

Have evolved to have various nutritional strategies

• Autotrophic because they absorb light but have pigments other than chlorophyll; they don’t do photosynthesis

• Chemotrophic because oxidate inorganic chemicals

• Heterotrophic because oxidate carbon compounds from other organisms

What are archaea?

Archaea are prokaryotes and extremophiles live in extreme environments

Definition herbivores

Animals that feed exclusively on plants

How are herbivores adapted to their diet?

• Herbivores have specialised mouthparts and styles

• Microbiomes

• Leaf-eating insects have chewing mouthparts like mandibles and piercing

Definitions predators

An animal that hunts and kills other animals for food

How are plants adapted to resist being eaten?

• Chemical: poisonous berries or other toxic substances

• Physical: spikes to prevent being eaten

What are some physical adaptations of predators?

• Speed of a cheetah

• An eagle that can spot prey from 3km away

• Vipers can detect body heat in their prey

• Chameleons have a long tongue to get insects

What are some chemical adaptations of predators?

• The cone snail injects an insulin-like venom into its prey

• Scorpions use venom to paralyze their prey

What are some behavioural adaptations of predators?

• Cheetahs are stealthy

• A group of dolphins can work together to surround a school of fish

Definition prey

Prey are animals that act as a food source to other animals

Physical adaptations of prey

• Owls have eyes on the side and a face that turns

• Rabbits have eyes on either side of their heads to give a large field of view

• Hedgehogs have numerous spines

• Zebras and chameleons are camouflaged to bend into their habitats

Behavioural adaptations of prey

• A population of mackerel form a ball of many fish to frighten predators

• Armadillos roll into balls and have thick skin

• Goats play dead when there are predators

• Possums play dead

Chemical adaptations of prey

• Skunks spray a pungent liquid from their anal glands

• Cinnabar caterpillars accumulate toxins in their tissues from the ragwort plant

• Possums release foam and stench from their anal glands

Definition omnivore

Animals that have a diet of both plant and animal origins

Differences in carnivore, herbivore and omnivore dentition

Diets are related to the muscular insertions and construction of jaws