B4.2 Ecological niches Flashcards
What is a ecological niche?
Ecological niche = role a species fulfils in an ecosystem. It includes zone of tolerance for abiotic & biotic variables which determine habitat (where it lives).
How is food obtained in an ecological niche?
Food is obtained via diff modes (photosynthesis or by consuming other organism) & competition is minimized.
What needs to be be done for organism to occupy a specific niche?
In order to occupy a specific niche, organism have to adapt physically & by behaviour.
What does the zone of tolerance determine?
Zones of tolerance for abiotic variables determine the habitat of a species - where it lives in ecosystem.
What is resource partitioning?
Species usually show adaptations to ecological niche which they occupy to avoid competition.
How are organism grouped into according to their oxygen requirements?
- Obligate aerobe
- Obligate anaerobe
- Facultative anaerobe
What is an obligate aerobe?
An organism that requires continuous O2 supply so only live in oxic environments. E.g. all animals & plant cells
What is an obligate anaerobe?
An organism which is inhibited or killed by O2 so only live in anoxic environments.
E.g. bacteria (clostridium tetani - tetanus bacterium)
What is an facultative anaerobes?
An organism the grow better with O2 but can live without it, lives in oxic or anoxic environments. E.g. Saccharomyces (yeast), Eschericia coli (gut bacterium)
What organisms use photosynthesis as a mode of nutrition?
- Algae e.g. perform photosynthesis
- Eukaryotic algae (e.g. seaweed or kelp) performs photosynthesis
- Plants (including mosses, ferns, conifers & lowering plants) use energy from sunlight to fix CO2 to produce sugars & other compounds
- Many types of bacteria (blue-green bacteria) & purple bacteria photosynthesize as a mode of nutrition
What decided the mode of nutrition of an organism?
Mode of nutrition of an organism depends a lot on its ecological niche & adaptations to biotic & abiotic factors.
what are the three mode of nutrition?
- Autotrophs
- Heterotrophs
- Mixotrophs
What is an autotrophs mode of nutrition?
Autotrophs synthesize organic compounds (sugars, amino acids, fats) by using other sources of energy.
What are the two methods for autotrophs mode of nutrition?
- Photoautotroph
- Chemoautotroph
What is a photoautotroph’s mode of nutrition?
Produces organic compounds from CO2, water & light energy through photosynthesis. (Plants, algae, protists, mosses, some bacteria.
What is a chemoautotroph’s mode of nutrition?
Produce organic compounds from other elements (e.g. iron or NH3) through chemosynthesis. (Archaea, bacteria)
What is an heterotrophs mode of nutrition?
Obtain organic compounds by consuming other organism internally or externally.
What are the three methods for autotrophs mode of nutrition?
- saprotrophs
- parasites
- holozoic
What is a saprotroph’s mode of nutrition?
Obtain food from dead & decaying matter by secreting enzymes & digesting externally. (Fungi, bacteria)
What is a parasitie’s mode of nutrition?
Obtain food from other organism without killing. (barnacle)
What is a Holozoic mode of nutrition?
Complex food particles are taken in & broken down.
What are the three types of Holozoic?
- Herbivore = ruminants such as goats, rabbits, cows
- Carnivore = Lion, tiger
- Omnivore = bear, human
What is a mixotroph’s mode of nutrition?
Perform both modes of nutrient uptake depending on availability - photosynthesis & by consuming. ( some protists (single-celled eukaryotes)
How do animals obtain nutrients?
Animals obtain their nutrients (carbohydrates, amino acids, fats) by consuming food. the large food molecules must be broken down into smaller ones before they can be absorbed into the blood stream body where they are needed.
What are the sequence of stages in holozoic nutrition?
- Ingestion: taking food into gut
- Digestion: breaking large food molecules into smaller molecules
- Absorption: transport of digested food across plasma membrane of epidermis cells & thus into blood & tissues of body
- Assimilation: using digested foods to synthesize proteins & other macromolecules & thus making them part of body’s tissue
- Egestion: voiding undigested material from end of gut
How do single celled organisms complete holozoic nutrition?
Single celled organisms e.g. amoeba, are also capable of holozoic nutrition - even without multi-organ controlled digestive system. Food particles are taken in by engulfment of substances (endocytosis) & subsequently broken-down & digested in specialized vesicles.
How do saprotrophs digest food?
Saprotrophs digest food by secreting enzymes to break down organic compounds externally. Products of digestion are then absorbed.
What organisms are saprotrophs? And what are they also called?
Bacteria and fungi are saprotrophic. also know as decomposers bc break down carbon compounds in dead organic matter & release elements e.g. nitrogen, allowing them to be used again by other organisms.
What is a mixotroph?
Mixotroph = organism that can use a mix of diff sources of energy & carbon, instead of having single mode of nutrition. Both autotrophs (photosynthesis) & heterotrophs (consume organisms). Tend to be unicellular eukaryotic cells (protists - marine plankton)
What are the two types of mixotrophs?
- facultative mixotroph
- obligate mixotroph
What is a facultative mixotroph?
Can be entirely autotrophic, entirely heterotrophic or use both modes.
What are obligate mixotrophs?
Must use both modes of nutrition. this is often case if a type of nutrient cannot be synthesized by themselves.
What is an example of a mixotroph?
Euglena gracilis is a single-celled eukaryotic algae that will photosynthesize (autotroph) in sufficient light, but can also ingest particles of food by phagocytosis, which it then digests (heterotrophs). It is facultative mixotroph.
What is archaea and what is it’s mode of nutrition?
Archaea are often adapted to life in extreme conditions e.g. hot springs, salt lakes or volcanic craters. They have a diverse mode of nutrition by being phototrophic (using light), chemotrophic (using Fe by oxidising) & heterotrophic (oxidising organic compounds from other organisms)
How is dentition and mode of nutrition (diet) linked?
Teeth give a lot of info about feeding style of an individual. Teeth of herbivores are large & flat to grind fibrous plant material. Omnivores tend to have a mix of diff types of teeth to break down both meat & plants in their diet. Human have molars in back of mouth are often flat to crush seeds, & sharper canines & incisors than herbivores to tear tougher food, e.g. meat.
What family are humans a part of?
Humans are part of family Hominidae, 1 of 2 families of ape superfamily Hominoidea, other being Hylobatidae.
How does different diets within the hominidea affect their dentition (Gorillas)?
Gorillas are mainly herbivore, feeding on large amount of vegetation each day. Their skull & jaws are adapted for this plant-based diet. Large masseter muscles connect skull with jaw, enabling animal to grind plant material between its teeth. Temporal muscles pull up jaw - this allows animals to bite food. Temporal area is part of skull, where these muscles attach: in gorillas, & other great apes, these areas are much larger than in humans. Gorillas also have a sagittal crest, to allow attachment for larger temporal muscle. This corresponds to need to bite fibrous plant material forcibly.
How does different diets within the hominidea affect their dentition (chimpanzees)?
Chimpanzees are primarily frugivores (feed on fruit) & only eat vegetation if other forms of food are limiting. Occasionally, chimpanzees eat meat (e.g. from monkey they have killed), so can have an omnivorous diet. Thus, have less-developed masseter & temporal muscles than gorillas.
what are the different types of teeth?
- incisors,
- canines
- premolars
- molars
What is the use of incisors?
Incisors are used for slicing food.
What is the use of canines?
Canines are for tearing.
What is the use of molars?
Molars are used for grinding food.
What is the difference between humans, gorillas and chimpanzees dentition?
Gorillas have more developed canine & incisors than humans, similar to chimpanzees, & larger premolars & molars for grinding tough vegetation.
What are the different diets within the hominidae family? How can this be deduced?
Species within Hominidae have a variety of diff diets, with gorillas mainly being herbivores, chimpanzees primarily frugivores. This isn’t deduced from dentation, but also from bones structure to which chewing muscles attach. E.g. early hominids Australopithecus & Paranthropus showed dental adaptations to tough vegetation with molars & premolars large & allowing for powerful chewing.
What the difference between human and the extinct Paranthropus robustus?
Paranthropus Robustus, had a skull that resembled that of a gorilla including a sagittal crest, due to diet of tough vegetation that sustained them. Species name ‘robustus’ refers to robust skull that they display, i.e. large teeth & strongly built jaws; in contrast, humans have a ‘gracile’ skull - a lighter, more slender structure P. robustus had megadont (=large teeth) cheek teeth, with thick enamel to cope with tough vegetation. Large molars & premolars helped in powerful chewing motion.
What was the dentition of human 7 million yrs ago?
- Incisors were relatively large, upper incisors were broad & projected outward
- Canines were very long & pointed, much larger in males than females
- Large canines in apes have been linked with more fighting between males for access to females.
- Developed incisors & canines also allow food to be grasped & bitten
what are the characteristics of human dentition & skull?
- Incisors = relatively small, narrow & vertical
- Canines = short & relatively blunt
- Molars = small
- ‘wisdom teeth’ = may be partially hidden or impacted due to shortening of jaw
- Premolars & molars = relatively flat with low, rounded cusps on grinding surface
- evolution –> larger cranial capacity in human increasing brain size, along with smaller teeth & V-shaped jaw (reflect diet, less tough vegetation & more omnivorous diet)
What are the two groups can insects by divided into for adaptation of their herbivorous diet?
- Insects with jaw-like mouthparts for biting off, chewing & ingesting pieces of leaf
- Insects with tubular mouthparts for piercing leaves or stems to feed on phloem sap
How have aphids adapted for their herbivorous diet?
Aphids have modified piercing mouth parts called stylets. These secrete enzyme pectinase to break down polysaccharide pectin which holds together cell wall of plants. That way style can easily pass between cell walls & access plant’s sap.
How have herbivorous animals adapted to their diet?
Herbivorous animals e.g. cows & sheep have specialized back teeth. Their digestive systems are specifically adapted to digesting plant matter. Bacteria & archaea living in rumen help to break down cellulose.
What are the adaptations of plants to resist herbivorous organisms?
- tough sharp-pointed spines to injure
- stings to cause pain
- synthesize substances (phytotoxins) that are toxic = secondary metabolites, stored in any part of plant, particularly seeds. Cause nausea, cardiac problems or hallucinations.
How has the castor beans adapted to resits herbivores?
Castor bean (Ricinus communis) produces seeds that contain ricin, which is highly toxic. In the manufacture of castor oil toxin is removed.
How have herbivores adapted to the plant toxins?
- Some animals have evolved ways of neutralizing toxins so that they aren’t poisoned.
- Some ruminants have microbes in their guts which can detoxify toxins, or proteins in saliva which can destroy toxin
- Liver in some mammals can also neutralize some toxins
How are predators adapted to be able to catch their prey?
- eye position = front of head enable better depth perception, use binocular vision to estimate distance to prey
- Specialised sense organs e.g. snakes use their tongue to pick up chemicals emitted from prey & special organ in the mouth
- Speed e.g. peregrine falcon fast in the sky
- Behavioural adaptation = team work e.g. hunt in pack to encircle the prey or ambush predators
- Venom or other toxins
- Pheromones = attract the prey
- Claws, teeth, beaks & well adapted digestive system to consume prey
How are vampire bats adapted to catch their prey?
Vampire bats have unique dentition, with small premolars & no molars but relatively large incisors & canines on their upper jaw that are pointed & razor-shape. These are used to pierce prey, so vampire can feed on blood.
How are black mambas adapted to catch their prey?
Black mambas produce venom containing a mixture of neurotoxins, including an inhibitor of enzyme acetylcholinesterase. Venom paralyzes prey when injected via poison fangs. Snake can then swallow prey without it resisting
How are grizzly bears adapted to catch their prey?
Grizzly bear learn ambush strategies for catching migrating salmon either by trial & error or copying others. some bears wait at top of waterfalls for a fish to jump out of water. Other put their heads underwater & watch for a fish swimming past.
How are prey adapted to resist to their predators?
- Chemicals = to poison predator or make them taste bad e.g. poison dart frog
- Camouflage = ability to take appearance of its surroundings
- Aposematism = mimic warnings, make seem like poisonous bc of bright colours
- Mechanical defences = protective shell, exoskeletons, clams, mussels so predator can’t eat them
- Behavioural adaptations = DNA encoded with behaviour e.g. fleeing, hiding, forming groups
- Eye positions = eyes on sides of their head –> good view of their surroundings & detect approaching predators
- Speed
How has the buff-tip moth adapted against predators?
Buff-tip moths resemble broken birch twigs, giving them camouflage when roosting during daylight hours on twigs or on ground. This is time when night-flying moths are most vulnerable to predation.
How has the caterpillars adapted against predators?
Caterpillars of the cinnabar moth feed on ragwort & accumulate toxic alkaloids from it. Their black & yellow stripes are warning coloration which deters predators. Adults are day-flying, with red & black warning coloration, indicating that they retain toxins obtained when larvae fed on ragwort.
How has the blue-striped snappers adapted against predators?
Blue-striped snappers swim in a tight group, often with sudden changes of direction. This “schooling” behaviour reduces chance of predation, bc threats are more likely to be detected & it’s difficult for a predator to catch any one individual in bewildering shoal.
How has plants adapted to harvesting light, in forest environments?
- Trees have a dominant leading shoot that grows rapidly to great height to reach forest canopy where they are unshaded by other tress
- Lianas climb through other trees, using them for support –> don’t need to produce as much xylem tissue (wood) as free-standing trees
What has these adaptation lead to?
The development of these strategies allow us to arrange them into diff layers of the forest.
How have epiphytes adapted to attain light?
Epiphytes get up into understorey or canopy to access sunlight,. Their roots attach to tree trunks & collect water trickling along branch.
How have lianas adapted to attain light?
Lianas are vines that take root on the forest floor & use trees as a scaffold to grow up high into canopy. Lianas seedlings do opposite to normal plants: they grow towards shade, which means they grow towards tree trunks, & can then start to climb. Act as direct competition with the trees for light & nutrients in soil.
How have leaves in the shrub layer or forest floor (shade) adapted?
Many plants, e.g. herbs, growing on forest floor or shrub layer are shade tolerant & don’t need a lot of sunlight Large surface areas of leaves help plants in the shrubs layer or forest floor to catch light. Well adapted to absorbing the wavelengths of diffuse sunlight that remains after passing through other leaves e.g. longer wavelengths in the red part of spectrum.
What is a species’ fundamental niche?
A species’ fundamental niche = full range of environmental & social conditions under which it could potentially survive & reproduce, taking into account all tolerance levels to abiotic & biotic factors.
What is a species’ realized niche?
The realized niche = specific set of conditions under which it actually does survive in a given habitat or ecosystem, with limitations of other species being present. These are conditions to which it is best adapted.
What happens to fundamental niche and realized niche of e.g. protists population when you grow with another species?
When grown alone under ideal conditions (fundamental niche), each population grew to a higher maximum. When grown together under same conditions, one population would typically dominate & other would die off. This example of realised niches vs fundamental niches & led to competitive exclusion principle.
What happens when two species share a niche?
If two species share a niche, this leads to inter-specific competition (competitive exclusion) for resources. Inevitably, one species will have an advantage over other with less well-adapted species struggling more to survive & reproduced. It will lead to one of them either becoming extinct, or forced to migrate
What is an example of competitive exclusion/ inter-specific competition?
Eurasian red squirrel (S. vulgaris) has suffered competitive exclusion due to introduction of Eastern grey squirrel (S. carolinensis) to UK from USA. S. carolinensis is larger, stronger& can store more fat in winter, making it better able survive & reproduce. It is more tolerant of habitat change than S. vulgaris. The red squirrel is now protected in many areas.
