ECOLOGICAL NICHES (B4.2)

What are specialist species?

Those species adapted to narrow habitats, limited food resources, or other specific environmental conditions. They are often the most vulnerable when conditions change

What are generalist species?

Those species adapted to a wide variety of habitats, food resources, and environmental conditions. They are more likely to survive when conditions change.

What is an ecological niche?

Where an organism lives, and its role and impacts on the ecosystem

What is a biotic factor?

Refers to living parts of an ecosystem; the interactions with the living parts of an environment such as competition with other species for resources, disease, predators, and parasites

What is an abiotic factor?

Non- living parts of the ecosystem like temp, precipitation, wind, sunlight, pH of water, soil

What are animals that are obligate anaerobes?

• Organisms that can only survive in environments that lack oxygen, as they lack the enzyme that enables them to deal with oxygen so it become toxic

• Rather than oxygen as the electron acceptor for respiration they use other compounds such as sulfate, nitrates, iron, manganese, mercury or carbon monoxide.

What are animals that are facultative anaerobes?

Microorganisms that are able to make ATP using oxygen if present, but if it is absent, it can switch to fermentation

What are animals that are obligate aerobes?

Organisms that can only survive in environments that contain oxygen.

What is photosynthetic nutrition?

• Use energy from the sun to generate their nutrition

• Autotrophs use this process to generate nutrition

• Specialised organelles called chloroplasts (found in leaves of plants) contain photosynthetic pigments that capture the light energy and convert it to organic molecules which can be stored within the plant, algae or prokaryote

What are autotrophic organisms ?

An organisms that can produce its own chemical energy using light, inorganic compounds or other energy sources

• EG: plants, algae

What are heterotrophic organisms?

An organism that cannot produce their own food, they must ingest nutrient from other organic sources

• EG: Humans, animals

What is holozoic nutrition?

• Organism that take in solid or liquid food internally

• Once food is brought inside the organism, it is digest into organic building blocks

• The used to build new materials for growth and development of the organism

What is mixotrophic nutrition? Give example of oraganism

• Able to use a combination of methods of generating nutrition and are neither fully autotrophic or heterotrophic

• Mixotrophic microbes are able to photosynthesise like a plant and therefore take in carbon dioxide, but can also take in nutrition like an animal. As they respire they then release carbon dioxide

• EG: Marine Plankton

What are facultative mixotrophs?

Switch between autotrophic and heterotrophic modes of nutrition depending on the conditions within the environment.

• Euglena is an example of a facultative mixotroph.

What is saprotrophic nutrition?

• A method by which the organisms secretes digestive enzymes that are able to break down the dead organic material

• Fungi and Bacteria are examples

• Can be referred to as decomposers

What are archaea?

• One of the classifications of living organisms

• Unicellular

• No nucleus

• Have polysaccarides make up their cell wall

• Have ability to survive in extreme environments

• Some are chemoautotrophs and some are photoautotrophs, some are heterotrophs

What are chemoautotrophs ?

An organism that derives energy from the oxidation of inorganic compounds via chemosynthesis.

What are photoautotrophs?

An organism that can make its own energy using light and carbon dioxide via the process of photosynthesis.

What are hominins?

All modern and extinct humans and their immediate ancestors

What are hominids?

Not only the hominins but also the great apes (such as gorillas, chimpanzees and orangutans).

How did the skull structure of early hominids show the details of their diet ?

• Had large teeth with thick enamel and chewed at the back of their jaw

• Had large chewing muscles which resulted in them having a wide face

• These are believed to be herbivores and to have eaten tough grasses and sedges

How did the skull structure of recent hominids show the details of their diet ?

• They had small brains but large teeth for their skull size.

• It is believed that they were omnivores and that their diet included both plant and uncooked meat.

• The evidence for this is the markings on their teeth that show wear that coincides with eating a tough fibrous diet that required a lot of chewing

What are herbivores?

Animals that eat only plant material

• EG: Cows, goats, sheep, hippos

How have herbivores adapted to feed on plants ?

• Insects have strong pair of mandibles one ahc side of their head which they use to cut, tear and crush and chew their food

• Some insects feed off fluids internal to the plant and use a unique straw-like device, called a stylet to access these

• Mammals have long and flat front incisors which work like scissors to cute the plant material

  • Back molars are large, flat surface where the plant material can get macerated in a sideways grinding movement to increase SA for digestive enzymes to break it down

  • The space between the incisors and molars is called a diastema, and this area allows the tongue to move the food from the front of the mouth towards the molars for grinding.

• Need to be aware for predators to have eyes fair apart to increase their visual field

What some adaptations of plants to avoid herbivory?

• Make toxic secondary compounds which are toxic to the people whoe at the plant

  • Evolved non-toxic chemicals that only become toxic after ingestion

• Thorns

• Thick, rigid leaves which are difficult to chew

• Plants have microscopic thorns called trichomes which deter much smaller herbivores like insects

• Release sticky resin or chemicals that cause irritation to the herbivore

• Camouflage to avoid being seen

What are the physical adaptations of predators to kill prey?

• Use speed and agility

• Sharp claws and teeth

• Digestive enzymes that can break down prey

• Finely tuned sensory systems

  • Eagle vision

  • Owl listening to movement

What are the chemical adaptations of predators to kill prey?

• Release certain chemical that work to either poison or paralyse their victims

  • EG: Venom containing toxins produced by black mambas

What are the behavioural adaptations of predators to kill prey?

• Dolphins work together to swim in a circular motion, and by beating their tail fin they stir up the sea bed to create a ring of mud.

• This works like a fishing net to catch their prey.

• The fish are effectively trapped and can only escape by jumping out of the water, and straight into the dolphins’ mouths.

What are the physical adaptations of prey to resist predation?

• Shells of limpets on rocky shores to protect soft parts of the mollusc's body

What are the chemical adaptations of prey to resist predation?

• In cinnabar moth larvae toxins are accumulated from eaten ragwort plants

What are the behavioural adaptations of prey to resist predation?

• Swimming in tight groups(schooling) in blue-striped snappers and other fish

What are some adaptations of plants to harvest light?

• Trees have a dominant leading shoot, allowing rapid growth in height up to the forest canopy so other tres do not case shade

• Lianas climb other trees, using them for support, so they need less xylem tissue(wood) than free standing trees

• Epiphytes grow on the trunks and branches of trees, so they receive higher light intensity than if they grew on the forest floor, but there is minimal soil for their roots.

• Strangler epiphytes climb up the trunks of trees, encircle them and outgrow the tree's branches, shading out its leaves. Eventually the tree dies leaving only the epiphyte.

• Shade-tolerant shrubs and herbs absorb the small amounts of light that reach the forest floor.

What is a fundamental niche?

The niche of an ecosystem in which an organism can live and reproduce

• Takes into account the environmental and social limitations for that organism but not other constraints like presense of other species

What is a realised niche?

The environmental condition in which the species actually lives.

• Formed when the species within a fundamental niche has to deal with the pressure of co-existing with the other species in the environment.

What is competitive exclusion?

• Where the fundamental niches of two species overlap, one species is expected to exclude the other from that part of its range by competition

What is an example of competitive exclusion?

• Paramecium aurelia and Paramecium caudatum.

• They both have similar needs for nutrition and space. If they are grown in separate containers, they can both thrive, but if they are combined within the same container, they will compete with each other leading to the extinction of P. caudatum.

What is niche partitioning?

The process by which competing species use the environment differently in a way that helps them to coexist. This may be spatial or temporal.