Species Abundance and Diversity
Sam
Billy Bob Joe
Bad Decisions
100
all species in a defined area, potentially interacting with each other
Community
100
groups that are defined taxonomically
Assemblages
100
s a group of species that use similar resources in a similar way (Ex.seed eating animals)
Guilds
100
is similar to a guild however is based on structure and growth dynamics (Ex.annuals)
Life-form:
200
What are the basic community attributes?
The species composition, species richness, species evenness, and the community dynamics.
200
What is a log-normal distribution and how do you interpret a graph with this distribution?
The log-normal distribution is a parabola. With the log of species abundance on the x-asxis vs. the number of species on the y-axis.
200
log-normal distribution
200
Why is it hard to estimate true species richness with sampling efforts?
It is hard to estimate the total number of richness within a community, due to the fact that the more you sample the closer you get to the true number, therefore every member in a community must be Accounted, for the true community richness.
300
How do we calculate species richness and diversity?
There are two ways to calculate species richness and diversity. The first way is the Species diversity Metrics (Shannon-Weiner diversity). The second way is the Rank abundance plots.
300
H’ = – Σ (Pi * ln(Pi))
Variable?
H’ - species diversity
Pi - the proportion of total individuals comprised of species i
S - Number of species in community
300
How to calculate the maximum possible species diversity.
Max Possible H’=ln(s)
300
Rank abundance plots show...
The rank abundance plot shows diversity, richness, and evenness.
400
Rank Abundance Plot
species richness in central gulf ? 57
400
Rank abundance plot X-axis and Y-axis
Xaxis - species rank ordering from most abundant (1) to least abundant
Yaxis - relative abundance for each species
400
Slope and line length mean in rank abundance plots
Slope - steep slope = low evenness
Shallow slope = high evenness
Length - short line = low richness
Long line = high richness
500
How do complexity and disturbance each affect species diversity?
Increased complexity means more niches, means more species. Disturbance has frequency and intensity, which removes organisms making room for other organism.
500
What is the intermediate disturbance hypothesis?
At intermediate disturbance we have maximum diversity. When disturbance is at high intensity or frequent only the adapted r-selected can survive. When disturbance is at low intensity or infrequent only the good competitors k-selected can survive.