B4.2: Ecological Niches

- The role of a species within its habitat

The role of a species includes

- What it eats

- Which other species depend on it for food

- What time of day a species is active

- Exactly where in a habitat a species lives

- Exactly where in a habitat a species feeds

- The role of a species within its habitat

The role of a species includes

- What it eats

- Which other species depend on it for food

- What time of day a species is active

- Exactly where in a habitat a species lives

- Exactly where in a habitat a species feeds

A niche specialist has a very narrow ecological role, depending on specific resources or habitats, which makes them highly efficient in stable environments but vulnerable to change.

A niche generalist has a broad ecological role, can survive in a wide range of conditions, and consume many different food sources, making them more adaptable and resilient to environmental shifts

Obligate aerobes require oxygen to live and use it for energy production through aerobic respiration.
Obligate anaerobes are killed by oxygen and can only grow in its absence, using fermentation or other anaerobic pathways.
Facultative anaerobes can switch between both, preferring aerobic respiration when oxygen is present but growing via anaerobic respiration or fermentation in its absence

State the energy and carbon sources utilized in photosynthesis. .

Saprotrophs digest externally through enzymes,

while detritivores digest internally in specialized digestive systems.

Bacteria
Archaea
Eukarya

Plants, algae, and a group of bacteria called cyanobacteria

Animals are holozoic heterotrophs. This means that they ingest food and digest it internally. Holozoic organisms can also be called consumers

Ingestion is the in take of food.
Digestion is the physical or chemical breakdown of food, so that it can be absorbed into the blood stream.
Absorption is the release of digested food into the blood stream.
Assimilation is the use of digested food in the organisms cells.

Some species are not exclusively autotrophic or heterotrophic, but can use both modes of nutrition. Species like this are mixotrophs.

Euglena is a single-celled organism that follows this mode of nutrition. It has chloroplasts for photosynthesis when light is available, but can also survive by eating algae or detritus (dead matter).
Euglena can survive with either mode, so it is a facultative mixotroph.

facultative mixotrophs: can survive with either mode of nutrition alone
obligate mixotrophs: require both modes of nutrition to survive.

Some fungi and some bacteria are heterotrophs, but digest their food externally and then absorb the digested monomers. These are saprotrophs, also called decomposers.

Detritivores digest internally, whereas saprotrophs digest externally

Costasiella kuroshimae is a sea slug that eats algae but instead of digesting their chloroplasts, it keeps them in its own body tissues and absorbs the sugars they produce until they degrade.

Many carnivorous plant species like Drosera capensis (right) perform photosynthesis, but also trap insects or other small animals.

All saprotrophs are decomposers because they break down dead organic matter, but not all decomposers are saprotrophs because the term "decomposer" also includes other organisms like detritivores that digest dead matter internally.

Archaeans are single-celled prokaryotes that live in diverse conditions, often very extreme (extreme temperatures, pH values, salinities, etc)

Photoautotrophs perform photosynthesis
Heterotrophs oxidize organic compounds
Chemotrophs oxidize inorganic compounds

Exant: the four genera of great apes: orangutans (\(Pongo\)), gorillas (\(Gorilla\)), chimpanzees and bonobos (\(Pan\)), and humans (\(Homo\)).
extinct: australopithecines, Paranthropus, Homo erectus, Homo heidelbergensis, Homo neanderthalensis, and Gigantopithecus

Carnivores like the leopard typically have long canines for gripping and tearing, and thin, sharp molars for slicing.

Herbivores like the cow typically have broad, flattened teeth for crushing tough plant matter.

Omnivores eat a mixture of the two.

All extant hominids are primarily herbivorous, but do include some animal foods (such as smaller mammals, lizards, insects, snails, and honey) in their diets, when available.
Dentition in hominids includes both flat molars for crushing, and sharp incisors for cutting food-adaptations for an omnivorous diet.

Aphids have piercing mouthparts, which they use to drink the sugary sap of green stems.

Monarch caterpillars have slicing and chewing mouthparts to consume leaves.

Plants acquire adaptations to resist herbivory, including:
- Thorns and other physical adaptations to deter herbivores
- Synthesis of toxic or bad-tasting chemicals in the leaves and stems

The cheetah (Acinonyx jubatus) has long legs, a spring-like spine, and non-retractable claws that all increase its speed and handling to capture prey.

Rattlesnakes produce venom that can stop the heart of prey species, allowing the rattlesnake to consume the prey without struggle.

Wolves work together in a pack to take down prey too large for a single wolf to kill, and then share the meal.

The African bush elephant (Loxodonta africana) is the largest living land animal. Its large size and its tusks are both examples of physical adaptations for avoiding predation.

Poison dart frogs accumulate toxins from their diet of ants in order to make themselves toxic to other predators. Like the monarch butterfly, poison dart frogs display warning coloration-bright colors that warn predators that the frog is toxic.

Bison herding behavior has many advantages-more eyes to spot predators, more adults to protect vulnerable young, and many targets to make it more difficult for a predator to isolate a single individual

Height
Adaptation: Reaching great heights allows plants to position themselves above their competitors and access more direct sunlight.
Example: Tall trees in a forest form the canopy, with the tallest individuals receiving the most sunlight.
Lianas
Adaptation: These are woody vines that grow from the ground but climb on other plants, using them as a support structure to reach the canopy.
Example: A liana twines its stems around a large tree trunk or uses tendrils to climb higher, aiming for the sun-drenched upper layers of the forest.
Epiphytes
Adaptation: Epiphytes, or "air plants," grow on other plants, such as trees, to get closer to the light in the canopy.
Example: Some epiphytes, like the Anthurium, have large, vertical leaves that efficiently capture the filtered sunlight that reaches them on the host tree.
Shade tolerance
Adaptation: Shade-tolerant plants have physiological and morphological adaptations to survive and grow in low-light conditions.
Example: A plant on the forest floor might have a higher concentration of photosynthetic pigments, a thin and broad leaf structure to maximize light absorption in the dim understory, and may have other adaptations like vertical leaves to collect light and avoid debris.
Leaf surface area
Adaptation: Leaves can increase their surface area to capture more light.
Example: Plants in the low-light forest understory often have large, dark green leaves to capture as many photons as possible. These leaves are angled to maximize light absorption

The fundamental niche is the full range of conditions where a species could potentially survive and reproduce,

the realized niche is the smaller, actual range of conditions it occupies due to limitations like competition, predation, and other species interactions.

The competitive exclusion principle says that two species can't coexist if they occupy exactly the same niche (competing for identical resources).

Species with identical niches also have identical needs, which means they would compete for precisely the same resources.

Organisms that can adapt to extreme niches encounter less competition and predation