Unit 8: Topic 5 - Community Ecology Flashcards
What is a community?
A group of populations of species in a specific area.
What is community ecology?
Community ecology is the study of the interactions between the species of a community. This can include commensalism, mutualism, parasitism or predation.
What is community structure?
Community structure is part of community ecology that is measured and described with species composition and species diversity. This basically means it is an analysis of how many species there are and how much of each species there are in a community.
What is the Simpson Diversity Index?
The Simpson Diversity Index is used to measure the diversity of a community. The equation is :
Diversity Index= 1-Σ(n/N)^2
n = the total number of organisms of a particular species
N = total number of organisms of all species
Σ= “sum of”
What is the Shannon Diversity Index?
The Shannon Diversity Index is an equation used to find species diversity.
The equation is: H=−∑[(pi)×ln(pi)]
Where pi is the proportion of each species (the number of organisms in a species over all the organisms in the community).
What causes communities to change?
Interactions between populations of species can cause communities to change.
What are interspecific interactions?
Interspecific interactions between populations determine how populations access matter and energy. These interactions can be classified as either negative or positive for a population.
What is mutualism?
Mutualism is a symbiotic relationship where both species benefit (Ex: Gut bacteria and humans)- (+/+).
What is commensalism?
Commensalism is a symbiotic relationship where one party is positively impacted and the other party is not affected (Ex: Barnacles and whales)- (0/+).
What is parasitism?
Parasitism is a symbiotic relationship where one party benefits and the other party is harmed. (Ex: Dogs and fleas) (-/+).
What is competition?
Competition is a symbiotic relationship where both parties are harmed. This is because when there is competition, it means that there is a lack of resources (food, water, space) to support both populations. This limits the survival and reproduction of members of each species. It can also lead to competitive exclusion where one species overpowers the other for resources causing the “weaker” species to go extinct. (Ex. Weeds in a garden) - (-/-).
What would the graph of prey and predator populations look like?
Because the predator eats the prey, and increase in the predator population would cause the decrease in the prey population. An increase in the prey population, however, would cause the predator population to also increase, though it would lag behind the prey population. However, the increased predator population would cause the prey population to fall again.
What are trophic cascades and how are they related to the predator-prey relationship?
Trophic cascades are when a change in population of one population of a food web indirectly impacts the population of another organism. This is related to the predator-prey relationship because as the population of the predator increases, the population of the prey decreases, but the population of the predator of the predator also decreases. In addition, if one predator has multiple food sources, an increase in the population of one prey can lead to the decrease in predation of another prey population.
What is niche partitioning and what is it an effect of?
Niche partitioning is an effect of competitive exclusion. It is when similar species differentiate the resources they use (through evolution), effectively creating two separate niches in order to limit the competition of the same resources. This allows for coexistence in a community.
How would competition, predation and symbioses impact the population of a species?
Competition, predation and parasitism would drive the population down. Mutualism would have positive impacts on the population and commensalism could increase the population or have no impact.
