B4.2 Ecological niches

explain biotic & abiotic interactions & how influence niche

niche - unique role a species plays in a community

involve biotic and abiotic factors

abiotic zone of tolerance determines the habitat

food supply:

• autotrophs make food using water & Co2

• heterotrophs feed on other organisms

to minimise competitions, species specialise in food sourcing - requiring adaptations

explain differences between obligate anaerobes, facultative anaerobes and obligate aerobes

• Obligate aerobes need oxygen (e.g. plants, animals, Micrococcus luteus).

• Obligate anaerobes die in oxygen (e.g. tetanus bacterium, methanogenic archaea).

• Facultative anaerobes use O₂ if present but tolerate anoxic conditions (e.g. gut bacteria, yeast)

summarise process of photosynthesis as mode of nutrition

• Sunlight is used to fix CO₂ and produce carbon compounds like sugars & amino acids.

• Occurs in:

  1. Plants (e.g. mosses, ferns, flowering plants)

  2. Eukaryotic algae (e.g. seaweed)

  3. Cyanobacteria

• Autotrophs make food from inorganic substances; Producers are consumed by others.

explain various modes of holozoic, mixotrophic, saprotrophic nutrition

• Holozoic: animals ingest, digest, absorb, assimilate, and egest food.

• Mixotrophic: organisms (e.g. Euglena gracilis) use both autotrophy and heterotrophy.

• Saprotrophic: feed on dead matter using external digestion (e.g. fungi)

give details of diversity of nutrition in archaea

• Chemoheterotrophs: oxidize carbon from other organisms.

• Photoheterotrophs: absorb light (not via chlorophyll); carbon from other organisms.

• Chemoautotrophs: oxidize inorganic chemicals; synthesize carbon from CO₂

summarise relationship between dentition and diet

• Herbivores: large, flat teeth for grinding plants.

• Omnivores: varied dentition for plants and meat.

• Humans: flat molars for crushing, sharp canines/incisors for tearing.

• Family includes Homo, Pongo, Gorilla, Pan.

infer diet of several hominid species form anatomical features

• Dentition shows dietary adaptations:

  • Flat molars = grinding (herbivory)

  • Sharp canines = tearing (meat)

• Diet inference based on tooth type and structure

describe adaptations of herbivores for feeding on plants

• Herbivores:

  • Beetles: mandibles for chewing leaves.

  • Aphids: tubular mouthparts for sap.

  • Butterflies: long mouthparts for nectar.

• Plants:

  • Physical: spines, stings.

  • Chemical: toxic secondary metabolites (e.g. in seeds).

• Specificity: herbivores evolve to detoxify specific plant compounds.

describe adaptations of predators for finding, catching and killing prey ad prey animals for resisting predation

• Predators:

  • Structural: sharp teeth (vampire bats).

  • Chemical: venom (black mamba).

  • Behavioral: luring (anglerfish).

• Prey:

  • Structural: shells (limpets).

  • Chemical: toxins (cinnabar moth larvae).

  • Behavioral: group movement (snappers).

describe adaptations of plants for harvesting light

• Trees: tall growth to reach canopy.

• Lianas: climb trees.

• Epiphytes: grow on trunks/branches for better light.

• Strangler epiphytes: outgrow host tree, block light.

• Shade-tolerant shrubs: survive with minimal light

describe and explain differences between fundamental and realised niche

• Fundamental niche: abiotic and biotic conditions species could occupy without competition.

• Realized niche: actual range occupied with competitors present.

explain concept of competitive exclusion and uniqueness of ecological niches

• If two species have overlapping fundamental niches, one may outcompete the other.

• The outcompeted species loses its realized niche and is excluded.

• Each species must have a unique realized niche to survive.