Ecological niches Flashcards
What is the definition of an ecological niche?
The role of a species within its habitat
What are the components of a species’ role in its habitat?
- 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
What is the niche exclusion principle?
No two species can fill the same niche within a habitat; if this ever happens the two species will be in direct competition with each other for resources, and one of the two species will out-compete the other, causing it to die out in that particular habitat
How can species appear to occupy the same niche but still have differences?
It can sometimes seem as though species are occupying the same niche, but there will still be subtle differences in their role; e.g. they might feed at different times of day, or have different food sources
What is an example of a feature that may differ between niches?
Feeding location is an example of a feature that may differ between niches
What is required for species to survive in their ecological niche?
Species can only survive in habitats in which they are well adapted to their niche; they must be adapted to a habitat’s:
- Abiotic factors
- Biotic factors
What are examples of adaptation to abiotic factors?
- Plants must have enough light for photosynthesis in order to produce carbohydrates.
- Aquatic organisms must be able to absorb enough oxygen from the surrounding water for respiration.
What are examples of adaptation to biotic factors?
- A prey organism being camouflaged to avoid predation.
- A plant growing fast enough to outcompete nearby plants for sunlight
What are the three categories of organisms based on their oxygen requirements for respiration?
- Obligate anaerobes
- Facultative anaerobes
- Obligate aerobes
What are obligate anaerobes and what is their relationship with oxygen?
Obligate anaerobes are single-celled organisms that can only carry out anaerobic respiration. They cannot tolerate oxygen. Early bacteria were obligate anaerobes. They can now only be found in oxygen-free environments, such as lower layers of soil, deep water, and inside the bodies of other groups of organisms.
What are facultative anaerobes and how do they handle different oxygen conditions?
Facultative anaerobes are organisms that mainly respire aerobically, but have the ability to switch fully to anaerobic respiration in the absence of oxygen. The switch to anaerobic respiration has no negative effects for facultative anaerobes. Examples include brewers yeast (Saccharomyces cerevisiae) and Escherichia coli.
What are obligate aerobes and how do they respond to oxygen availability?
Obligate aerobes are organisms that cannot survive in the absence of oxygen; they rely on aerobic respiration to release energy from food. They may be able to carry out anaerobic respiration in some cells for short periods, but the damaging effects are too great to do this for longer than a few seconds. Examples include most animals, most fungi (not yeast), and some bacteria (e.g. Mycobacterium tuberculosis).
How did the introduction of photosynthesis affect obligate anaerobes?
Photosynthesis introduced oxygen to the Earth’s atmosphere, meaning that obligate anaerobes can now only be found in oxygen-free environments, whereas they were able to survive in the atmosphere of early Earth due to its lack of oxygen.
What is the key difference between aerobic and anaerobic respiration?
Aerobic respiration requires oxygen, while anaerobic respiration does not require oxygen.
What are some examples of oxygen-free environments where obligate anaerobes can be found?
Lower layers of soil, deep water, and inside the bodies of other groups of organisms.
How long can obligate aerobes carry out anaerobic respiration in some cells?
For short periods, but the damaging effects are too great to do this for longer than a few seconds.
What are the two main modes of nutrition for organisms?
Autotrophy and heterotrophy. Autotrophs synthesize their own organic molecules from simple inorganic substances. Heterotrophs gain organic molecules from the tissues of other organisms.
How do autotrophs differ from heterotrophs?
Autotrophs produce organic molecules from inorganic substances (e.g., photoautotrophs use light energy, chemoautotrophs use chemical energy). Heterotrophs obtain organic molecules by consuming other organisms.
What is photosynthesis, and which organisms perform it?
Photosynthesis is the process by which autotrophs use light energy to convert carbon dioxide into organic molecules like carbohydrates. It is carried out by plants (terrestrial/aquatic), algae (single-celled or multicellular), and some photosynthetic prokaryotes.
What role do photosynthetic pigments like chlorophyll play?
Photosynthetic pigments absorb light energy, enabling the conversion of carbon dioxide into organic molecules during photosynthesis.
Why are photosynthetic organisms called producers?
They synthesize organic molecules independently, forming the foundation of food chains by transferring energy to other organisms.
What are two critical ecological roles of photosynthesis?
- Transfers light energy into chemical energy usable by living organisms.
- Releases oxygen into Earth’s atmosphere, enabling aerobic respiration.
How does photosynthesis bridge non-living and living matter?
It converts inorganic carbon dioxide (from the environment) into organic molecules (used by living organisms), sustaining ecosystems.
Name three groups of photosynthetic organisms.
- Plants (terrestrial and aquatic)
- Algae (including single-celled and seaweeds)
- Photosynthetic prokaryotes (no further details required).
What should never be said about energy?
Be careful with yourlanguage when discussing energy;you should NEVER saythat energyis
produced or created,onlythat it is transferred from one form to another.Photoautotrophs do
not produceenergy,theyproduce their own food bytransferring light energyto chemical
energy.
What are heterotrophs, and what example is given in the text?
Heterotrophs are organisms that gain organic molecules from the tissues of other organisms. For example, all animals are heterotrophs.
What defines holozoic nutrition?
Holozoic nutrition involves heterotrophs gaining organic molecules by ingesting, digesting, absorbing, and assimilating molecules from the tissues of other organisms.
What are the four stages of holozoic nutrition?
- Ingestion (eating)
- Digesting (breaking down larger molecules into smaller molecules)
- Absorbing (transporting molecules into cells)
- Assimilation (using molecules to build cells and tissues).
What is the critical requirement for holozoic nutrition?
Holozoic nutrition requires internal digestion.
How do house flies differ from organisms using holozoic nutrition?
House flies secrete enzymes onto their food before absorbing the products. They are heterotrophs but do not use holozoic nutrition because digestion occurs externally, not internally.
What is the difference between ingestion and absorption?
Ingestion refers to eating food, while absorption involves transporting digested molecules from the digestive tract into cells.
What is assimilation in holozoic nutrition?
Assimilation is the process of using absorbed molecules to build and repair cells and tissues.
What is a mixotroph?
A mixotroph is an organism that uses more than one method of nutrition, such as combining autotrophy (producing organic molecules) and heterotrophy (consuming organic molecules).
What distinguishes obligate mixotrophs from facultative mixotrophs?
Obligate mixotrophs require constant access to both autotrophic and heterotrophic nutrition, while facultative mixotrophs primarily use one method of nutrition but supplement it with the other.
How does Euglena exemplify mixotrophic nutrition?
Euglena is a single-celled freshwater protist that uses autotrophy (photosynthesis via chloroplasts) and heterotrophy (engulfing bacteria via endocytosis and digesting them with lysosomal enzymes). It positions itself using a light-sensitive spot to maximize light absorption.
What are two examples of mixotrophic organisms besides Euglena?
Carnivorous plants (e.g., use photosynthesis and digest insects) and corals (gain nutrients from symbiotic algae and filter-feeding). Marine plankton, such as dinoflagellates, also exhibit mixotrophy by photosynthesizing and feeding on bacteria.
How do carnivorous plants demonstrate mixotrophic nutrition?
Carnivorous plants produce organic molecules through photosynthesis while supplementing their nutrition by digesting insects to obtain additional nutrients.
How do corals acquire organic molecules mixotrophically?
orals obtain organic molecules from symbiotic photosynthetic algae (autotrophy) and by filter-feeding on particles in surrounding water (heterotrophy).
What role do marine plankton like dinoflagellates play in mixotrophy?
Marine dinoflagellates float in ocean water and use photosynthesis (autotrophy) while also feeding on bacteria (heterotrophy), making them mixotrophic.
What structural feature helps Euglena optimize photosynthesis?
Euglena has a light-sensitive spot that allows it to position itself for maximum light exposure to its chloroplasts.
What is the significance of lysosomes in Euglena’s heterotrophic nutrition?
Lysosomes in Euglena store digestive enzymes used to break down bacterial cells ingested via endocytosis.
What are saprotrophs and how do they obtain nutrition?
Saprotrophs are heterotrophs that ingest the tissues of dead organisms and waste material by secreting enzymes onto their food and digesting it externally before absorbing the products of this digestion.
How does saprotrophic nutrition differ from holozoic nutrition?
In saprotrophic nutrition, digestion takes place externally, while in holozoic nutrition, digestion occurs internally.
What are examples of saprotrophs and what can they be described as?
Examples of saprotrophs include fungi and bacteria. These organisms can be described as decomposers.
What types of enzymes do saprotrophs secrete and what do they do?
Saprotrophs secrete a wide range of digestive enzymes that allow them to hydrolyse a large variety of biological molecules, and so to release a large range of products.
What are examples of products released by saprotrophs?
Examples of these products include mineral ions, such as ammonium ions and phosphate ions.
How do saprotrophs benefit other organisms in their ecosystem?
Not all of the products of external digestion get absorbed by saprotrophs, leaving some minerals in the surrounding soil for absorption by other organisms, such as plants.
Why are saprotrophs essential to ecosystems and food webs?
Without saprotrophs the nutrients locked up in dead and waste matter would never be released and plants would not have access to sufficient minerals.
What is the key difference between decomposers (like fungi) and detritivores (like earthworms)?
Both decomposers and detritivores feed on dead organisms and waste material, but decomposers are saprotrophs and use external digestion, while detritivores digest their food internally using holozoic nutrition.
What are the three main nutritional groups of archaea?
- Phototrophic archaea
- Chemotrophic archaea (including chemoautotrophs and chemoheterotrophs)
- Heterotrophic archaea
How do phototrophic archaea generate ATP?
Phototrophic archaea use energy from light to generate ATP. They use pigments like bacteriorhodopsin to absorb light energy and pump H+ ions across a membrane, creating an ion gradient that leads to ATP production via ATP synthase.
What is the difference between phototrophic archaea and oxygen-releasing photosynthesis?
Phototrophic archaea do not release oxygen and are not considered autotrophic. They are often described as photoheterotrophs, using light energy for ATP production but obtaining carbon compounds from other organisms.
What are chemoautotrophs in archaea?
Chemoautotrophs are archaea that produce their own carbon compounds using chemosynthesis. They use energy released from chemicals in the environment to produce their own carbon compounds.
What are some examples of chemicals that can act as energy sources for chemosynthetic archaea?
- Hydrogen gas
- Ammonia
- Methane
- Hydrogen sulfide
How do chemoheterotrophic archaea differ from chemoautotrophs?
Chemoheterotrophic archaea use chemicals to produce ATP but gain their carbon compounds from other organisms, while chemoautotrophs produce their own carbon compounds.
How do heterotrophic archaea obtain and use carbon compounds?
Heterotrophic archaea gain their carbon compounds from other organisms, and then use these carbon compounds to generate ATP.
What are the three domains of life, and which one includes archaea?
The three domains of life are Bacteria, Archaea, and Eukarya. Archaea make up one of these three domains.
What is chemosynthesis in archaea?
Chemosynthesis is a process where archaea release energy from chemicals and transfer it to carbon compounds, which can then be used for ATP production.
How do some chemotrophic archaea directly drive ATP production?
Some chemotrophic archaea use energy from chemicals to directly drive ATP production in a similar way to phototrophic archaea, using an ion gradient across a membrane.
Give an example of heterotrophic archaea.
An example of heterotrophic archaea are those that break down and absorb carbon compounds in dead plant material.
What level of taxonomic detail is expected for examples of archaea?
You are not expected to give examples of archaea at the species level.
What family do humans belong to, and what other animals are in this family?
Humans are part of the Hominidae family, along with chimps, gorillas, orangutans, and gibbons.
What order contains the Hominidae family?
The Primate order contains the Hominidae family.
What is the diet of most existing hominids?
Most existing hominids are omnivores, meaning that their nutrition comes from a combination of animal and plant material
What is the main diet of chimps?
Chimps are mainly frugivores, meaning that their main diet consists of fruit, though they do eat other plant matter and some small mammals.
What is the main diet of gorillas?
Gorillas are mainly herbivores, feeding primarily on leafy vegetation, though they do sometimes eat insects.
How are chimp jaw muscles adapted to their diet?
Chimps have relatively small jaw muscles which are only strong enough to chew softer fruit and animal tissue.
How are gorilla jaw muscles adapted to their diet?
Gorillas have very strong jaw muscles for biting and grinding tough vegetation.
How are chimp teeth adapted to their diet?
Chimps have small incisor teeth and long canine teeth, enabling them to bite and tear meat.
How are gorilla teeth adapted to their diet?
Gorillas have large molar and premolar teeth for grinding vegetation.
What is the function of incisor teeth?
Incisor teeth are chisel shaped for cutting and biting.
What is the function of canine teeth?
Canine teeth are pointed for holding and tearing.
What is the function of premolars and molars?
Premolars and molars are flat and ridged for grinding.
How do species’ teeth types and sizes relate to their diet?
Species will often have different combinations of teeth types and sizes to enable them to better chew and digest their diet.
How can the principle of diet-dentition relationship be applied to extinct hominid species?
We know that there is a relationship between diet and the dentition in currently existing hominid species, and it is possible to apply this principle to extinct hominid species.
What allows scientists to study the diets of extinct hominid species?
The skulls and jaws of extinct species are often well preserved and can be studied. This allows scientists to find out about the diets of these extinct species, as well as the ecosystem structures in which they lived.
Why aren’t teeth always a perfect indicator of diet?
It is worth noting that while dentition can sometimes be clearly linked to diet, teeth don’t always give a perfect indication of what a species eats, e.g.
- Existing humans eat quite a lot of meat, but have teeth that are more similar to plant-eaters
- Orangutans and gorillas have pointed canines but do not eat meat
- Male chimps have longer canines than females despite not having a different diet
- Teeth may play a role in other processes, e.g. defending territory, or competing for mates
What additional method can scientists use to study fossil teeth for diet information?
E.g. scientists can study fossil teeth under a microscope to look for patterns of abrasion which may indicate diet more clearly.
Name four examples of extinct hominids.
Examples of extinct hominids include:
- Australopithecus africanus
- Paranthropus robustus
- Homo floresiensis
- Homo neanderthalensis
What does fossil evidence suggest about the diet of Paranthropus robustus?
- Fossil evidence from Paranthrapus robustus suggests that they had a diet of tough plant material
- Their skull shape was similar to that of modern gorillas; robust in shape, and with attachment points for large jaw muscles for chewing tough vegetation
- Large molars and premolars for grinding vegetation
- Thick tooth enamel to protect the tooth from being damaged by tough plant matter
What does fossil evidence suggest about the diet of Homo floresiensis?
- Fossil evidence from Homo floresiensis suggests that they were primarily plant eaters, but that they may have eaten some meat
- They had large premolar teeth and small canines
- Their jaws were square and robust; a feature that is similar to plant-eating gorillas
- Tooth abrasion suggests a fibrous, plant-based diet
- Their skulls are more similar in shape to humans that to other human ancestors, suggesting a reduction in the biting forces used
- Evidence of hunting/cutting tools provides additional evidence of meat eating behaviour
Where can some fossils be viewed as part of digital collections?
Some fossils are available to view as part of digital collections, e.g. from the Smithsonian Institution, the Paleontological Research Institution, and the North Carolina School of Science and Mathematics.
Which 3D specimens should be considered for examining to infer diet from anatomical features?
Consider examining 3D specimens of Homo sapiens, Homo floresiensis, and Paranthropus robustus to infer diet from anatomical features.
What were the key features of Paranthropus robustus’ skull?
Paranthropus robustus had a skull ridge for the attachment of large jaw muscles and a robust skull shape similar to modern gorillas.
What were the key features of Homo floresiensis’ skull?
Homo floresiensis had small canine teeth and a skull similar in shape to modern humans.
How do scientists begin their work in studying hominid diets?
Scientists begin their work by making observations, e.g. observing how the teeth of existing Hominids relates to their diet.
How are theories developed from observations in the study of hominid diets?
Observations can then be used to develop theories, e.g. that the diet of extinct Hominids can be deduced by looking at their dentition.
Why is it important to consider new evidence in scientific theories?
While such theories and deductions are a valuable part of the scientific process, it is important that new evidence is taken into account as it arises.
What do discrepancies between dentition and diets of modern hominids tell scientists?
Discrepancies between the dentition and diets of modern hominids tell scientists that their deductions about extinct species may be flawed, and that additional sources of evidence may be needed.
What is an example of how theories about hominid diets might need to be reassessed?
E.g. discrepancies between the dentition and diets of modern hominids tell scientists that their deductions about extinct species may be flawed, and that additional sources of evidence may be needed.
What are herbivores?
Herbivores are heterotrophs that feed on plants.
What are adaptations?
Adaptations are characteristics that aid an organism’s survival in its environment.
How are aphid mouthparts adapted for herbivory?
Aphids have specialised mouthparts known as stylets that are able to pierce plant tissues to reach the sugary sap inside the phloem.
What type of mouthparts do caterpillars, grasshoppers, and beetles have for herbivory?
Insects such as caterpillars, grasshoppers and beetles have mouthparts called mandibles which allow them to cut through leaves.
How are grazing mammals’ teeth adapted for herbivory?
Grazing animals such as sheep and horses have flat teeth for grinding plant matter.
How are ruminant mammals’ digestive systems adapted for herbivory?
Ruminant mammals such as cattle and deer have stomachs with several compartments from which they can regurgitate and re-chew their food, breaking down plant matter into smaller pieces to aid digestion.
How do ruminants break down cellulose?
Ruminants have specialised communities of bacteria that live in their digestive tracts which aid the breakdown of cellulose. The bacteria have the enzymes needed to break down cellulose, while the herbivores do not.
How do some mammals neutralize plant toxins?
Some deer produce proteins in their saliva that bind to toxins called tannins. Proboscis monkeys have gut bacteria that can neutralize certain toxins found in leaves.
What is ‘cautious sampling’ in mammals?
Mammals may use ‘cautious sampling’ when they first encounter a new plant, meaning that any toxic chemicals will not be consumed in large enough quantities to be dangerous.
What are predators and prey?
Predators are animals that hunt and eat other animals, or consume the tissues of recently dead animals. Prey are animals that are hunted and consumed by predators.
What are the three types of adaptations in predators and prey?
Chemical, Physical, and Behavioural adaptations.
What are chemical adaptations?
Chemical compounds that assist in the catching of prey or the avoidance of predation.
What are physical adaptations?
Physical features, such as specially adapted sense organs, that assist in the catching of prey or the avoidance of predation.
What are behavioural adaptations?
Behaviours that aid the catching of prey or the avoidance of predation.
Give examples of chemical adaptations in predators
- Snakes producing haemotoxic or neurotoxic venoms
- Scorpions producing neurotoxic venom
- Spiders producing various types of toxins
What is chemical mimicry and how do some predators use it?
Chemical mimicry is a strategy where predators release chemical pheromones to attract prey. For example, bolas spiders release pheromones normally used by female moths to attract mates, enabling them to catch male moths as prey.
What is chemical crypsis and how do some predators use it?
Chemical crypsis, or scent camouflage, allows ambush predators to lie in wait for prey without being detected. For example, the prey of pirate perch fish seem unable to detect their presence, possibly due to the production of a chemical which acts as camouflage.
How do haemotoxic venoms affect prey?
Haemotoxic venoms, produced by snakes such as adders and rattlesnakes, damage the circulatory system, e.g., by interfering with blood clotting.
How do neurotoxic venoms affect prey?
Neurotoxic venoms, produced by snakes such as mambas and cobras, interfere with the passage of nerve impulses.
What sensory adaptation do birds of prey have?
Birds of prey have excellent vision that allows them to detect small prey animal movement from a distance.
How are predators’ eyes typically positioned?
The eyes of predators are often located in the fronts of their skulls, giving good distance perception.
What is the Jacobson’s organ in snakes?
The Jacobson’s organ is located in the roof of the mouth and allows snakes to use their tongues to detect chemicals that may be released by prey animals.
How do bats detect prey?
Bats can detect and process information generated by sound waves bouncing off prey organisms, allowing them to find prey using echolocation.
What physical adaptations allow cheetahs to run at high speeds?
Cheetahs can run at high speeds as a result of their long limbs and flexible spines.
How fast can swordfish swim and why?
Swordfish can swim at 60 mph due to their streamlined body shape.
What adaptation do carnivorous mammals have for catching prey?
Carnivorous mammals have large canine teeth which allow them to catch and hold onto prey.
What is an ambush predator?
Ambush predators lie in wait without moving for extended periods before attacking prey.
Give an example of an ambush predator.
Puff adders can remain motionless for weeks at a time while they wait for prey to come near.
What is a pack predator?
Pack predators cooperate with each other to increase their chance of success, e.g. orcas, wolves and lions.
What are two types of pursuit predators?
Pursuit predators chase after their prey, either using a burst of speed (e.g. cheetahs) or persistence hunting over long distances (e.g. wolves and painted dogs).
What are some examples of chemical adaptations in prey animals?
- Poison dart frogs produce skin toxins that can kill predators
- Skunks produce unpleasant-smelling chemicals to deter predators
- Tiger moths contain chemicals that make them taste unpleasant to bat predators
How do some prey animals use scent camouflage?
- Puff adders produce chemicals that prevent detection by predators like mongooses
- Harlequin filefish take on the scent of corals they feed on, making them undetectable to predators
How are prey animals’ eyes typically positioned?
Prey tend to have eyes positioned on the sides of their skulls, giving a wide field of vision.
What is camouflage in prey animals?
Camouflage allows prey to blend in with their surroundings, e.g. some insects have bodies that appear to be leaves or sticks.
What is mimicry in prey animals?
Mimicry allows prey to look like predators or other dangerous species. For example, owl butterflies have wing patterns resembling owl eyes, and king snakes mimic the coloration of venomous coral snakes.
What is aposematism?
Aposematism is the development of bright warning colors that signal chemical defenses to predators, such as the brightly colored skin of poison dart frogs.
What are some examples of mechanical defenses in prey animals?
- Tough exoskeletons in insects and crustaceans
- Tough shells in turtles
- Spines in porcupines and hedgehogs
What is an example of an innate preference in prey animals?
Prey animals like woodlice have an innate preference for dark, sheltered places and will move around constantly until they encounter a dark hiding place.
How do rabbits respond to potential aerial predators?
Rabbits will run into their burrows when they see birds with the wing shape of predators.
How do some prey animals avoid predators through timing?
Some prey may avoid locations or times of day where predators are present. For example, desert rodents may spend the daytime in an underground burrow and only emerge at night.
What are two benefits of prey animals grouping together?
Grouping together reduces their chance of being caught and can potentially confuse predators.
What is an example of group behavior in fish?
Shoals of fish move together in ways that make individual animals difficult to pick out.
What is “mobbing” behavior in prey animals?
Some prey animals will ‘mob’ a predator. For example, gulls may group together to attack a predator and drive it away.
How do some prey animals warn others of danger?
Some individuals may be able to warn others in a group of the presence of a predator, e.g., by using a warning call or by running away.
What is a “bluffing” technique used by some prey animals?
Bluffing techniques allow prey animals to convince predators that they are not what they seem. For example, opossums, some species of snake, and some species of shark may pretend to be dead to cause predators to lose interest.
How do frill-necked lizards use bluffing?
Frill-necked lizards may use their large neck frill to pretend to be larger than they really are.
What is the primary purpose of plant adaptations for light harvesting?
To maximize their ability to absorb light energy for photosynthesis.
What are “form adaptations” in plants?
Whole organism adaptations that maximize their ability to absorb light energy for photosynthesis.
What is the canopy in a forest ecosystem?
The uppermost layer of plants, made up of trees.
What are emergent trees?
Trees that grow above the main canopy.
What is the understory in a forest?
A layer of trees beneath the main canopy.
How does maximizing height benefit trees in a forest?
It allows the tallest trees to gain the most sunlight, as there are no other plants between them and the sunlight.
What are lianas?
Woody vines that use the trunks of trees as their main supporting structure to gain height.
How do lianas grow in a forest?
They germinate on the forest floor, grow toward the base of tree trunks, and then grow upwards.
How do lianas obtain nutrients and moisture?
Their roots are in the soil, allowing them to gain nutrients and moisture from the ground.
What resources do lianas compete with trees for?
Light, nutrients, and moisture.
What are epiphytes and how do they increase their absorption of sunlight?
Epiphytes are plants that grow high up in tree branches to increase their absorption of sunlight, but they do not begin their lives on the forest floor and often gain their nutrients from high in the canopy.
How do different epiphytes obtain water and nutrients?
- Moss gains water and nutrients from rainwater that runs across the tree bark
- Bromeliads collect rainwater amongst their leaves
- Some orchid species have aerial roots which absorb moisture directly from the air
What is the advantage of epiphytes over other plants?
Epiphytes have the advantage of height for gaining light energy, but do not need to expend their energy on upward growth.
What are strangler epiphytes and how do they differ from lianas?
Strangler epiphytes grow roots downward to the forest floor to gain nutrients and water, while still taking advantage of height from trees to absorb sunlight. Unlike lianas, strangler epiphytes begin their lives in the canopy, not on the forest floor.
What is an example of a strangler epiphyte and how does it grow?
The strangler fig is an example. It begins its life in the canopy and is able to grow both upwards and downwards to maximize its access to resources. It can kill its tree host by taking all of its resources.
How are shade-tolerant plants adapted to grow on the forest floor?
They are adapted to absorb the limited range of light wavelengths that reach the ground through the leaves of the canopy and understory. They may contain different photosynthetic pigments to absorb different wavelengths of light.
How do ground-living plants maximize light absorption?
They often have especially large leaves, maximizing the surface area available for light absorption.
How do ground-living plants attract pollinators in low light levels?
They often produce very brightly colored or strongly scented flowers to attract pollinators.
What is the difference between shrubs and herbaceous plants?
Shrubs are not tall like trees, but they do have woody stems. Herbaceous plants, or ‘herbs’, lack woody stems and rely on soft tissues with turgid cells for support.
What is the definition of a species’ niche?
The role of a species within its habitat.
What two factors does a species’ role take into account?
- The biotic interactions of the species (e.g., organisms it feeds on and those that feed on it)
- The abiotic interactions (e.g., how much oxygen and carbon dioxide the species exchanges with the atmosphere)
What is the fundamental niche of a species?
The full range of conditions and resources in which a species could survive and reproduce, based on its adaptations and tolerance limits.
What is the realized niche of a species?
The actual conditions and resources in which a species exists, due to biotic interactions.
What barnacle species is used as an example to illustrate the difference between fundamental and realized niches?
Chthamalus dalli.
What is the fundamental niche of Chthamalus dalli?
A wide range of rocky intertidal areas in the Pacific Northwest, where it can attach to a variety of substrates and tolerate a wide range of temperature and salinity conditions.
What species competes with Chthamalus dalli and affects its realized niche?
Balanus glandula.
How is the realized niche of Chthamalus dalli different from its fundamental niche?
Its realized niche is much smaller, restricted to areas where Balanus glandula is absent or scarce, such as higher up on the shore.
Why is Chthamalus dalli found higher up on the shore in its realized niche?
It is exposed to air for longer periods of time and can avoid competition with Balanus glandula for space and resources.
What is the main reason for the difference between Chthamalus dalli’s fundamental and realized niches?
Biotic interactions with other species, specifically competition with Balanus glandula.
What is the fundamental niche?
The niche a species would occupy if there were no limiting factors in the environment or resources the species could use.
What is the realized niche?
The niche that a species actually occupies, in the presence of competitor species.
How does the fundamental niche relate to species distribution?
It represents the potential distribution of a species.
How does the realized niche relate to species distribution?
It represents the actual distribution of a species.
What ecological factors are absent in the fundamental niche?
No competition for resources, no predation.
What ecological factors are present in the realized niche?
Competition for resources and predation occurs.
How does the size of the fundamental niche compare to the realized niche?
The fundamental niche is large in size, while the realized niche is small in size.
For Chthamalus barnacles, what characterizes their fundamental niche?
Wide range of rocky intertidal areas in the Pacific Northwest, can attach to a variety of substrates and tolerate a wide range of temperature and salinity conditions.
For Chthamalus barnacles, what characterizes their realized niche?
Restricted to areas where competing species (e.g., Balanus glandula) are absent or scarce, such as higher up on the shore where it is exposed to air for longer periods.
What is the principle of niche occupancy?
A niche can only be occupied by one species, meaning that every individual species has its own unique niche.
What happens when two species try to occupy the same niche?
If two species try to occupy the same niche, they will compete with each other for the same resources.
What are the possible outcomes of competition between two species for the same niche?
- One of the species will be more successful and out-compete the other until the second species is either:
- Forced to occupy a new, slightly different niche
- Made locally extinct - Both species are forced into a smaller part of their fundamental niches
What is competitive exclusion?
The elimination of a competing species from its niche is known as competitive exclusion.
What is an example of competitive exclusion in warblers?
A possible consequence of different species of warbler competing for the same resources is that the most successful competitor will exclude other species from their niche, pushing them into slightly different niches, e.g. the location in which they feed may change.
What is a classic example of competitive exclusion?
A classic example of competitive exclusion is between two species of single-celled free-living protozoans:
- Paramecium aurelia
- Paramecium caudatum
How do Paramecium aurelia and Paramecium caudatum grow when cultured separately?
When each species is grown separately from each other both species will thrive.
What happens when Paramecium aurelia and Paramecium caudatum are grown together?
When the two species are grown in the same habitat they compete for resources and eventually P. aurelia outcompetes P. caudatum for these resources, which leads to P. caudatum’s elimination.
What limitation should be noted about the Paramecium example?
It is worth noting that this example involves both species being grown under laboratory conditions; it is rare in nature that two species will occupy exactly the same niche.
