B4.2 Ecological Niches

Guiding Questions:

  • What are the advantages of specialized modes of nutrition to living organisms?

  • How are the adaptations of a species related to its niche in an ecosystem

B4.2.1 Ecological niches as the role of a species in an ecosystem

  • niche: unique role that a species plays in the community

    • includes where it lives, what it eats, and interactions with other species

B4.2.2 Differences between organisms that are obligate anaerobes, facultative anaerobes and obligate aerobes

  • aerobic respiration: chemical transformation of food nutrients into energy that requires oxygen

  • anaerobic respiration: chemical transformation of food into energy that doesn’t require oxygen

  • hypoxia: reduced oxygen in an environment

  • anoxia: no oxygen in an environment

  • obligate anaerobes: intolerant of oxygen

  • facultative anaerobes: can carry out both aerobic and anaerobic respiration

  • obligate aerobes: need oxygen

B4.2.3 Photosynthesis as the mode of nutrition in plants, algae, and several groups of photosynthetic prokaryotes

  • organisms make their own food

B4.2.4 Holozoic nutrition in animals

  • all animals are heterotrophic

  • holozoic nutrition: food is ingested and digested internally

B4.2.5 Mixotrophic nutrition in some protists

  • mixotrophic: capable of making their own food AND ingesting nutrients externally

  • example → euglena: single-celled species that can undergo photosynthesis but also ingest food from water around it

B4.2.6 Saprotrophic nutrition in some fungi and bacteria

  • saprotrophic nutrition: secreting digestive enzymes then absorbing products of digestion

  • decomposers

    • fungi and bacteria

  1. secretes enzymes into dead tissue of organism to break down complex molcules

  1. then absorbs the now simpler energy-rich carbon compounds released due to enzymes

B4.2.7 Diversity of nutrition in archaea

  • methods to obtain nutrients and energy:

    • photosynthesis → generating energy using sunlight

    • chemosynthesis → generating energy from reactions involving inorganic molecules

      → chemoautotroph: organism capable of producing its own food using chemical reactions WITHOUT sunlight

    • heterotrophic nutrition → obtaining nutrients by eating other organisms

B4.2.8 Relationship between dentition and the diet of omnivorous and herbivorous representative members of the family Hominidae

  • the more serrated the teeth → better adapted for eating meat

  • the more rounded or blunt the teeth → better adapted for eating plant materials

B4.2.9 Adaptations of herbivores for feeding on plants and of plants for resisting herbivory

  • how herbivores adapt to eating plant material:

    → animals, example being cows, have bacteria and archaea in their digestive systems to break down the cellulose

  • how plants protect themselves from herbivory:

    → thick bark and thorns

    → chemical irritants

    → phytotoxins (plant poisons) made from secondary compounds can cause physical illness to the organism consuming the plant

    • example: foxglove

B4.2.11 Adaptations of plant form for harvesting light

Fundamental and realized niches

- Competitive exclusion and the uniqueness of ecological niches

- Relationship between dentition and the diet of omnivorous and herbivorous representative members of the family Hominidae

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

- Adaptations of plant form for harvesting light