Topic 8.5 - Community Ecology 𖦹⋆｡°✩ Flashcards
what is the structure of a community described according to
described according to species composition and diversity
what is a community
a group of different species living together in the same location and interacting with one another
what are communities described based on
༻ species diversity
༻ species composition
what is species diversity
the variety of species and the quantity of individuals included in each species within a given community
what is an example of species diversity
an ocean community consists of one species of shark and one species of sea turtle, yet there are 15 sharks and 62 sea turtles
what is species composition
the identity of each species in the community
what is an example of species composition
an ocean community consists of Pomacanthus paru and Pomacanthus xanthometopon, two species of angelfish
what is the Simpson’s Diversity Index
an equation used to measure the biodiversity of a habitat
what does it mean if there is a higher diversity index value
the community is more diverse
what sample of an environment is used to calculate the diversity index
random samples of the environment
what does a community changing over time depend on
interactions between populations
what is one type of interaction that can affect how populations access energy and matter
competition
what can competition result in
in a change in community structure
between whom can competition arise
can occur with or between species competing for food and habitats
what are the two types of positive interactions
༻ mutualism/symbiosis - both species benefit
༻ commensalism - one species benefits but the other is not harmed
what are the two types of negative interactions
༻ predator-prey - one species uses another as a food source
༻ parasitism - one species benefits at the harm of another
what affect do neutral interactions have and provide an example
have no impact on the species involved. for example, deer or rabbits living in a forest
what determines how populations access energy and matter
interactions among populations
what is an example of populations interacting with one another. explain
bracket/shelf fungi are tree parasites with 4 main functions:
༻ produce fruiting bodies that grow on tree bark
༻ absorb nutrients from the outer bark, which can weaken the external tree structure. however, reduced canopy and reduced foliage density can free up resources. on the other hand, it can infect the tree’s interior which may rot the tree and cause branches or the entire tree to fall. this provides new niches and habitats
༻ provide microhabitats for bugs since they can live in the holes the fungi make in the tree bark
༻ provide a food source for insects and other organisms because some insects use fungi as a food source
how can the relationships among interacting populations be modeled
can be characterized by positive and negative effects and modeled
when would an increase in predator populations be seen
an increase in predator populations occurs slightly after an increase in prey populations, but will eventually cause a decrease in prey populations
what is a trophic cascade
the negative effect the removal of or decrease in a key species has on other trophic levels
what will happen to the population as a result of the removal of a key species
populations can experience exponential growth or death, which results in the interruption of the flow of energy through the ecosystem and resource availability
what is niche partitioning
a decrease in competition over limited resources between two similar species because each species is accessing the resource in different ways
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