Chapter 54 Community Ecology Flashcards
What is a community?
An assemble of populations of various species living close enough for potential interaction
What are interspecific interactions?
Interactions in a community that either help, harm, or have no effect on the species involved
What are some examples of interspecific interactions? (5)
- competition
- predation
- herbivory
- symbiosis (parasitism, mutualism, and commensalism)
- facilitation
What is interspecific competition?
Occurs when species compete for a resource in a short supply
What is negative/negative interaction? Provide an example.
Interaction between species are harmful on each other
Example: Interspecific competition
What is competitive exclusion?
Local elimination of a competing species
What is the competitive exclusion principle?
States that 2 species competing for the same limiting resources cannot coexist in the same place.
What is ecological niche?
The sum of a species’ use of biotic and abiotic resources
What is resource partitioning?
Differentiation of ecological niches, enabling similar species to coexist in a community
What is a species’ fundamental niche?
The niche potentially occupied by that species
What is a species’ realized niche?
The niche that is actually occupied by that species
What is character displacement?
Tendency for characteristics to be more divergent in sympatric populations of two species than in allopatric populations of the same two species
What is predation?
An interaction in which one species, the predator, kills and eat the other, the prey
What is positive/negative interaction? Provide 2 examples.
One species benefits from the interaction, the other species is harmed
Example: Predation and Herbivory
What are some feeding adaptations of predators? (3)
- claws
- fangs
- poison
What are the various types of defensive adaptations of prey? (5)
- Behavioral defenses
- Morphological defenses
- Physiological defenses
- Mechanical/chemical defenses
What is aposematic coloration?
A bright warning coloration as an effective chemical defense of animals
What is cryptic coloration?
Camouflage/ coloration that makes prey difficult to spot
What is atesian mimicry?
Palatable or harmless species mimics an unpalatable or harmful model
What is Mullerian mimicry?
Two or unpalatable species resemble each other
Can mimicry also be used by predators?
Yes, predators can use mimicry to confuse/manipulate the prey
What is herbivory?
Refers to an interaction in which an herbivore eats parts of a plant of algae
What is symbiosis?
Relationship where two or more species live in direct and intimate contact with one another
What happens in parasitism?
One organism, the parasite, derives nourishment from another organism, its host, which is harmed in the process
What are endoparasites?
Parasites that live within the body of their host
What are ectoparasites?
Parasites that live on the external surface of a host
What is positive/positive interaction? Provide an example.
Interspecific interaction that benefits both species.
Example: Mutualism
What are the two types of mutualism?
- Obligate
- Facultative
What is obligate mutualism?
One species cannot survive without the other
What is facultative mutualism?
Both species can survive alone
What is positive/zero interaction? Provide an example
Interspecific interaction where one species benefit but the other species is not harmed/helped
Example: Commensalism
What is faciliation?
Interaction in which one species has positive effects on another species without direct and intimate contact
What are the two fundamental features of community structure?
- Species diversity
- Feeding relationships
What is species diversity?
The variety of organisms that make up the community
What are the two components of species diversity?
- Species richness
- Relative abundance
What is species richness?
The number of different species in the community
What is relative abundance?
Proportion of each species that represents of all individuals in the community
What is the Shannon diversity index?
A diversity index that compares diversity of communities
H = - (pA ln pA + pB ln pB + pC ln pC + …)
What are the 4 characteristics of communities with higher diversity?
- More productive; they produce more biomass (the total mass of all organisms)
- More stable in their productivity
- Better able to withstand and recover from environmental stresses
- More resistant to invasive species, organisms that become established outside their native range
What is trophic structure?
The feeding relationships between organisms in a community
What do food chains do?
Link trophic levels from producers to top carnivores
What is a food web?
A branching food chain with complex trophic interactions
What does the energetic hypothesis suggest?
Suggests that the length is limited by inefficient energy transfer
What is important about the energy stored in the organic matter?
Only about 10% of the energy stored in organic matter at each trophic level is converted to organic matter at the next trophic level
What are dominant species?
Species that are the most abundant or have the highest biomass
What are invasive species?
Species that are typically introduced to a new environment by humans and become dominant due to a lack of predators or disease
What are keystone species?
Species that exert strong control on a community by their ecological roles or niches
What are ecosystem engineers?
Foundation species that cause physical changes in the environment that affect community structure
What is the bottom-up model?
A model that proposes a unidirectional influence from lower to higher trophic levels
N (nutrient) -> V (plants) -> H (herbivores) -> P(predators)
What is top-down model?
The trophic cascade model that proposes that control comes from the trophic level above
In this case, predators limit herbivores, herbivores limit plants, and plants limit nutrient levels
N <- V <- H <- P
What does biomanipulation help with?
Helps to restore polluted communities
What is a disturbance?
An event that changes a community, removes organisms from it, and alters resource availability
What is a nonequlilibrium model?
A model that describes communities as constantly changing after being buffeted by disturbances
What are the most significant sources of disturbances in ecosystems? (2)
- storms
- fires
What is high level of disturbance a result of?
A high intensity and high frequency of disturbance
What is low levels of disturbance a result of?
Low frequency or low intensity of disturbance
What does the intermediate disturbance hypothesis state?
States that moderate levels of disturbance can foster greater diversity than either high or low levels of disturbance
What is ecological succesion?
The sequence of community changes after a disturbance
What is primary succession?
Succession that occurs where no soil exists when succession begins
begins from nothing
What is secondary succession?
Succession that begins in an area where soil remains after a disturbance
What does human disturbance due to a community’s species diversity?
Reduces its species diversity
What are the two key factors that affect a community’s species diversity?
- Latitude
- Area
What are the two key factors in equatorial-polar gradients of species richness?
- Evolutionary history
- Climate
What are the 2 main climatic factors correlated with biodiversity?
- sunlight
- precipitation
What is evapotranspiration?
Evaporation of water from soil plus transpiration of water from plants
What does the species-area curve quantify?
Quantifies the idea that, all other factors being equal, a larger geographic area has more species
S = cA^z
S is the number of species, c is a constant, A is the area, and z represents how many more species should be found as habitat area increases
What are pathogens?
Disease-causing microorganisms, viruses, viroids, and prions
What are zoonotic pathogens?
Pathogens that have been transferred from other animals to humans
What is a vector?
Transfer of pathogens that are direct or through an intermediate species
What is an example of a vector?
Malaria that goes to a human from a mosquito
