13. Community Ecology Flashcards
What is a Community in Ecology?
In ecology, a community is a group or association of populations of two or more different species occupying the same geographical area at the same time
What are interspecific interactions?
Ecologists call relationships between species in a community interspecific interactions
What is Competition?
Competition = (–/– interaction)
occurs when species compete for a resource in short supply
– For example, a lioness competing with hyenas for its kill
What is Predatation?
How do Predator and Prey Interact?
Predation (+/– interaction)
refers to the interaction where one species kills and eats the other (predator and prey)
– Some feeding adaptations of predators are claws, teeth, fangs, stingers, and poison
– Behavioral defences include hiding, fleeing, forming herds or schools, self-defence, and alarm calls
– Animals also have morphological and physiological defence adaptations
– Cryptic coloration, or camouflage, makes prey difficult to spot since they blend in with their surroundings
What is Cryptic coloration?
(Know Example)
Cryptic coloration, or camouflage, makes prey difficult to spot since they blend in with their surroundings
What is aposematic coloration?
Animals with effective chemical defense often exhibit bright warning coloration, called aposematic coloration
o Aposematic patterns typically show strong color contrast with background, unlike cryptic patterns
o Conspicuous colors, especially patterns of black and white, black and red, or black and yellow, have one thing in common: they visually shout “danger!”
o Predators that ignore this coloration and eat the organisms will experience their unpleasant taste or presence of toxic chemicals and learn not to eat them in the future
What is Batesian mimicry?
In Batesian mimicry, a harmless organism imitates the appearance of a dangerous or bad-tasting one in hopes that it will be mistaken for them by predators and be left alone
o For example, the caterpillar of the hawkmoth possesses the rather unique ability to inflate its abdomen in response to the external stimulus of a predator [the markings on the enlarged abdomen clearly resemble the eyes and general shape of a poisonous snake, with which the predator, most likely a bird, would not take chances getting close to]
What is Müllerian mimicry?
In Müllerian mimicry, two or more unpalatable or harmful species that have the same predator(s) resemble each other’s closely similar warning systems, such as the same pattern of bright colors
o Each species gains an additional advantage because the more unpalatable or harmful species there are, the more likely predators will avoid them
What are Two Examples of Müllerian mimicry?
o Example 1 = the viceroy butterfly appears very similar to the noxioustasting monarch butterfly [although for a long time thought to be an example of Batesian mimicry, the viceroy has recently been discovered to be just as unpalatable as the monarch, making this a case of Müllerian mimicry]
o Example 2 = the cuckoo bee and yellow jacket wasp occupy the same habitat and both have yellow and black stripes [predators avoid them because of the chemical content of their stingers and similarity in appearance]
What is aggressive mimicry?
This type of mimicry allows the predator to approach and sometimes attract its prey
Examples of Aggressive Mimicry
(3)
Example 1 = Anglerfish typically have at least one long filament (the illicium) sprouting from the middle of the head, protruding above the fish’s eyes and terminating in an irregular growth of flesh (the esca) at the tip of the filament [the filament can move in all directions and the esca can be wiggled so as to resemble a prey animal, thus acting as bait to lure other predators close enough for the anglerfish to devour them]
Example 2 = Frogmouth catfish have a tongue extension that looks like food other fish might like to eat (this lures prey to a position where they become an easy catch by the catfish)
Example 3 (aggressive mimicry need not involve the sense of vision) = The assassin bug preys on spiders, entering their web and plucking its silk threads, which produces vibrations that match the pattern of vibrations made by typical prey caught in the web, causing the spider to approach
What is Herbivory?
Herbivory (+/– interaction)
refers to an interaction in which an herbivore eats parts of a plant or alga
– It has led to evolution of plant mechanical and chemical defenses and adaptations by herbivores
– Plants counter excessive herbivory with physical defenses such as thorns and chemical defenses such as distasteful or toxic compounds
What is Symbiosis?
Symbiosis is a relationship where two or more species live in direct and intimate contact with one another
What is Parasitism?
parasitism (+/– interaction),
one organism, the parasite, derives nourishment from another organism, its host, which is harmed in the process
Examples –
fleas or mosquitoes feeding on blood from other organisms;
aphids consume sap from plants;
tapeworms deprive host organisms of food and nourishment
What are endoparasites?
Parasites that live within the body of their host are called endoparasites
What are ectoparasites?
parasites that live on the external surface of a host are ectoparasites
What is Mutualistic symbiosis, or mutualism?
Mutualistic symbiosis, or mutualism
(+/+ interaction),
is an interspecific interaction that benefits both species
5 Examples of Mutalism
What is commensalism?
In commensalism (+/0 interaction),
one species benefits and the other is apparently unaffected
Summary of Interspecific Interaction
What is Trophic Structure?
Trophic structure is the feeding relationships between organisms in a community
What is a Food Chain?
A food chain is a linear sequence of organisms through which nutrients pass as one organism eats another
Example of Producers and Consumers
How is Energy Transferred Through the Food Chain
Notice that at each level of the food chain, about 90% of the energy is lost in the form of heat
The total energy passed from one level to the next is only about one-tenth of the energy received from the previous organism
Energy Transfer Example
What is a Food Web?
A food web is a branching food chain with complex trophic interactions
– In food webs, arrows point from an organism that is eaten to the organism that eats it
