Community Ecology Flashcards
What does community ecology attempt to describe?
The distribution and abundance of species living in a local area
How is regional diversity gained and lost?
Gained by immigration and speciation
Lost by mass extinctions and dispersal
What creates local diversity?
Habitat selection by the individuals in the regional pool
How is local diversity gained and lost?
Gained by habitat selection
Lost by drift, stochastic extinction
Selection by competition and predation also matters
What determines the structure of a community?
Types of species, the number of species, the relative abundance of each species
What will be present in a community?
Autotrophs, primary consumers, secondary consumers, tertiary consumers, detritivores, decomposers
What determines if a species is considered to be abundant or rare?
Biomass, the area occupied, the number of individuals
Why would one or a few species be dominant in a community?
Good at competition, low predation, aggressive behaviour
What is diversity?
The number of species and their relative abundance
What is species richness?
The number of species in a community
What is species evenness?
The relative abundance and variation in a community
What is the Shannon Weiner Diversity index?
A combination of species richness and the number of individuals per species. The number is meaningless unless compared
When is diversity the highest?
When all species are equally abundant
What does Simpson’s index tell us?
How likely it is to randomly choose two individuals that are exactly the same
What is α-diversity?
Number of species in a habitat
What is β-diversity?
Number of unique species between 2 habitats
What causes a high β-diversity?
Different species in each new place, big change in the environment from place to place
What is gamma-diversity?
Number of species in a region
What determines diversity?
Physical structure of the environment, species interactions, and disturbances
How does habitat heterogeneity relate to diversity?
Environment can support more species, have a heterogenous resource distribution, which minimizes competition and stops 1 species from becoming dominant
What is species zonation?
Changes in the physical and biological structures of a community as the landscape changes
How does zonation affect species?
Different survival rates, different reproduction rates, alters competition and tolerance
How do species interactions influence diversity?
Realized niche, a species may be unable to tolerate the conditions because of interactions with other species
Between abiotic conditions and biotic factors, which determines a) what species are present
b) which species are dominant or rare
a) abiotic conditions
b) biotic factors
