Ecological niche

What is an ecological niche?

The unique role that a species plays in the community

Includes its spatial habitat, its feeding activities, and its interactions with other species

What is the spatial habitat?

The physical area inhabited by any particular organism

What is tolerance and what is an example of low tolerance?

How well a species reacts to the presence of something in its environment

Example: An organism with low tolerance to oxygen gas means it does not survive well when the gas is present

What are obligate anaerobes and where do they live?

Single-celled organisms that have no tolerance to the presence of oxygen and are poisoned by it

To escape from Earth’s atmosphere, obligate anaerobes live in places where the air cannot reach them, such as in soil, deep water, or the intestines of animals, including humans

What are facultative anaerobes and what is an example?

Capable of carrying out both anaerobic and aerobic respiration

Example: Baker’s yeast is a single-celled fungus

What are obligate aerobes?

Require oxygen and cannot convert food nutrients into energy without it

What happens in the case of hypoxia or anoxia (and what are they) for obligate aerobes?

If oxygen in their environment is greatly reduced (hypoxia) or absent (anoxia), these organisms die

What is holozoic nutrition?

Getting nutrients by ingesting all or part of an organism

The eaten organism’s parts are ingested and broken down into nutrients (digested) that can then be absorbed into the bloodstream (absorption) and used within the body (assimilation)

Organisms that obtain their food in this way are called consumers

What is mixotrophic nutrition?

Organisms that are both autotrophic and heterotrophic

Capable of making their own food and ingesting nutrients from other organisms

What are examples of species that employ mixotrophic nutrition?

The genus Euglena is made up of species that are single-celled protists that have photosynthetic pigments and can also ingest food from the water around it

What is the difference between obligate mixotrophs and facultative mixotrophs?

Obligate mixotrophs need both systems to grow and thrive

Facultative mixotrophs can survive on one system but use the other as a supplement

What are the three domains that living things can be classified into?

Bacteria, Archaea, and Eukarya

What are three methods that organisms in the domain Archaea use to obtain nutrients and energy?

Photosynthesis

Chemosynthesis

Heterotrophic nutrition

What family do homosapiens belong to?

We belong to the family Hominidae, the great apes

What are the locations of the incisors, canines, premolars, and molars? (IMAGE)

Incisors: found at the front of your mouth

Canines: To the side of the incisors

Premolars: middle of the mouth

Molars at the back of the mouth

What are incisors used for?

For cutting off bite-sized pieces of food

Which primates have large incisors? do herbivores or carnivores have larger incisors?

Those that eat mostly plant material such as leaves (folivores) and fruit (frugivores)

ex. Herbivores tend to have bigger incisors than carnivores

What are canines used for?

Sharper and used for ripping and tearing tougher materials such as meat

What are premolars used for?

For crushing or slicing up food

What are molars used for?

For grinding food and reducing it to a paste before swallowing

How are premolars and molars adapted for eating meat?

The more pointed the crowns of the premolars and molars are, the better adapted they are for eating meat

What are extant species?

Those that are not extinct at the time of writing

What does the fossil jawbone of Homo floresiensis tell us about their diet? What does archaeological evidence tell us?

The small canines and flat, broad molars suggest a plant-sized diet

However, tools and other archaeological evidence indicate that they wer hunters, so they probably consumed some meat as well

What is microwear?

Small abrasions or removal of a tooth’s surface made as organisms chew, which can reveal the type of food they were eating

Why are plants not easy to eat?

Not many organisms possess the enzymes necessary to break down cellulose

How are aphids adapted to eating plant material?

Use modified mouthparts called stylets

Pierce the plants and drink the sugar dissolved in the sap inside

How are grasshoppers and caterpillars adapted to eating plant material?

Use their sharp pinching mandibles to cut into grass baldes and leaves, to help ingest them

How are herbivores vertebrates such as cows and sheep adapted to eating plant material?

Have specialized back teeth that are broad and flat for grinding plant matter

Digestive system harbour bacteria and archaea that help break down cellulose

What does it mean that cows are ruminants?

They swallow grass or hay before fully chewing it, then regurgitate it later when they are resting to chew it more (chewing cud)

What are 2 adaptations of giraffes for eating plants?

Long legs and necks

Tough tongues to resist pointy thorns

What are 2 examples of physical adaptations of plants for defending themselves from herbivores?

Thick bark is difficult for many insects and some animals to penetrate

Thorns and spikes are useful for deterring herbivores

What is the adaptation of the common nettle for protection from animals?

Tiny hairs of silica on its stem and on the underside of leaves are filled with chemical irritants

When animals approach the plants and rub against them, the silica breaks, scratching the skin, and the irritant inside is released into the damaged skin

What are phytotoxins?

Plant poisons made from secondary compounds and can cause nausea, cardiac problems, or hallucinations when ingested

Why do castor beans require phytotoxins? What phytotoxin does it produce?

Castor beans produce seeds rich in nutritious oil, making them tempting to eat

To protect the seeds from animals that want to eat them, the plant produces a phytotoxin called ricin, which is highly toxic

How do animals evolve in defense to phytotoxins?

Animals evolve ways of neutralizing the toxins so that they are not poisoned

How do animals evolve in defense to phytotoxins?

Animals evolve ways of neutralizing the toxins so that they are not poisoned

What is one example of a means of neutralizing toxins?

In ruminants and insects that rely on microbes for digestion, the microbes can detoxify many plant poisons

What is cautious sampling?

Animals do not eat too much off a plant the first time it is encountered

What are two types of chemical adaptations for predators?

Inject chemicals into prey

Chemical compounds used to lure prey trickery

What is an example of injecting chemicals into prey?

Black mamba injects venom which contains neurotoxins that paralyse prey

What are pheromones?

Organic molecules used to send messages through the air and some are intended to attract mates

What is an example of pheromones used to lure prey by trickery?

Certain species of orb-weaver spiders are capable of producing chemicals that mimic the sex pheromones of moths

They release the pheromones and wait for prey to arrive

What are 4 physical adaptations that help predators find prey?

Excellent eyesight or night vision
Echolocation

Electrolocation (generate electric fields, sensing organs detect changes in electromagnetic fields)

Acute sense of smell

What are 3 adaptations that help predators catch prey and eat them?

The ability to move rapidly with precision

Claws, beaks, teeth, and a well-adapted digested system are needed to kill prey and extract nutrients

Brain that can quickly assess circumstances

What are 4 examples of behavioural adaptations?

Ambush predators

Pack hunting

Pursuit predators

Persistence hunting

What are ambush predators? What is an example?

Hide and wait for prey to come near and then pounce on them

Anglerfish hide on the ocean floor and use a lure called an illicium (a long thin appendage protruding from head) to attract prey

What is required for pack hunting? What is an example of a species?

There must be an established relationship of trust between individuals. The group knows which animal is the leader of the pack

What are pursuit predators? What is an example?

Relies on speed to outrun its prey

Example: cheetahs

What is persistence hunting? What is an example?

Pursuing the prey for many honours until it drops from fatigue

Humans living as hunter gatherers use persistence hunting

What is an example of a chemical adaptation for prey to resist predation? What is a specific example?

Produce chemicals that taste bad or that poison the predator

Example: Poison dart frogs produce an alkaloid on its skin that can interfere with muscle function, causing death

What are 3 examples of physical adaptations of prey?

Camouflage

Aposematism

Protective shell

What is aposematism? What are two examples?

Advertising dangerous nature of prey to predators

Poison dart forgs use dramatically bright and unusual colours to inform poisonous

Warning vocalizations can deter predators and warn fellow prey that there is danger (ex. jays and blackbirds)

What are 3 examples of behavioural adaptations of prey that are instinctive?

Fleeing at the sight of a predator

Hiding

Forming groups

What are the 4 layers of a forest eocsystem?

Canopy - upper layer of a forest where the crowns of trees are found

Understorey - zone below the canopy with shorter trees

Shrub layer - contains shortest trees and shrub

Forest floor - home to smaller, non-woody plants

What adaptation do liana vines demonstrate to maximize access to sunlight?

Liana seedlings grow towards tree trunks and use trees as a scaffold, allowing them to grow into the canopy to obtain more light

Liana vines are direct competitors for trees, for sunlight, and for minerals/space on the forest floor

What adaptation do epiphytes demonstrate to maximize access to sunlight?

Attach their roots to tree trunks and climb the trees to access sunlight

Obtain moisture from water trickling along the branch when it rains or from humidity in the air

What are hemi-epiphytes?

Spend early part of life in a tree without any roots in the soil

In addition to pushing stems upward to get more sunlight, they push stems downwards to reach the ground and start growing roots

How are shade-tolerant shrubs adapted to growing on the forest floor?

Adapted to absorbing the wavelengths of sunlight that remain after passing through other leaves, notably the longer wavelengths in the red part of the spectrum

What are herbaceous plants, otherwise called herbs?

Those that do not produce a woody stem with bark the way trees do

Grow in the understorey of forests in the tropics and are well adapted to growing in the shade

What is the fundamental niche vs realized niche of a species? Why might they be different?

Fundamental niche - the potential niche it could inhabit, given the adaptations of the species and its tolerance limits

Realized niche - actual niche it inhabits

Can be different because of competition with other species

What is the fundamental niche of the red fox in the USA?

Habitat is the forest edge

Food consists of small mammals, amphibians, and insects

Interacts with species like mosquitos that suck its blood and scavengers that eat its leftovers

What is the red fox’s realized niche in recent decades (3 reasons)?

Forest edge has been turned into farmland

Species eaten by the red fox no longer live there (ex. amphibians sensitive to pesticides)

Direct competition with coyote

What is the principle of competitive exclusion?

No two species in a community occupy the same niche

If they do coexist for a certain period of time, the number of both populations will decrease

What are 2 possible outcomes of competition between two species?

Elimination of one of the competing species

Restriction of both to a part of their fundamental niche

Summarize experiment by Russian ecologist G. F Gause showing the competitive exclusion principle.

When two different species of Paramecium were cultured together with a constant food supply, one died out while the other survived