Chapter 18 - Community Structure Flashcards
How might ecologists categorize communities?
By dominant organisms or physical conditions that affect species distribution
Is it common for ecologists to study every species in a community?
No, they typically choose subsets to study.
What is an ecotone?
A boundary created by sharp changes in environmental conditions over a relatively short distance, accompanied by a major change in the composition of species.
How can we document the existence of an ecotone?
Line-transect surveys
What is species richness?
The number of species in a community.
What is species richness?
The number of species in a community.
What is relative abundance?
The proportion of individuals in a community represented by each species.
What is a log-normal distribution?
A normal, or bell-shaped, distribution that uses a logarithmic scale on the x-axis.
What is a rank-abundance curve?
A curve that plots the relative abundance of each species in a community in rank order from the most abundant species to the least abundant.
What is species evenness?
A comparison of the relative abundance of each species in a community.
How have researches examined the effects of resources on species diveristy?
By determining correlations between productivity and species richness in nature.
What is the most common relationship between species richness and productivity? What does this mean?
Hump-shaped curve. Medium productivity has higher richness than high or low productivity.
What does increased fertility due to producer communities? Why?
Decline in species richness; species with competitive advantages outcompete other species, causing the more competitive to increase in number while the others decline/become nonexistant.
How does habitat diversity affect species richness?
Increases it
What is a keystone species?
A species that substantially affects the structure of communities despite the fact that individuals of that species might not be particularly numerous.
