species richness and diversity Flashcards
how do you know you had enough samples in a species effort curve graph?
the number of new species decreases at high sampling efforts (the curve vlakt af)
what causes the difference between rarefaction graph and a species effort curve graph?
randomization procedure
what is species richness?
Number of species (S), not abundance
when can you compare the species richness for two areas without any calculations etc?
when you have conclusive species lists of the areas
how do you compare species richness of two areas when you use samples?
with a species effort curve
when two lines follow the same path in species effort curve what does it mean?
species richness is the same
What is the difference between species richness and species diversity?
Species diversity incorporates species richness and the relative abundance of the species. Species richness does not.
why can’t you use ratios to calculate species richness?
because richness does not increase linearly with sample size.
how to compare lines in a species effort curve?
you cut them off where sample size is equal, and then do rarefaction to find out the numbers at that sample size.
what are the problems with rarefaction?
-It assumes species occur randomly, but in reality they are often clustered.
-you can’t extrapolate to total species amount
how to calculate max number of species?
Chao index
Chao index formula?
Smax = Sobs +(singletons^2/2*doubletons)
what is species evenness?
the degree to which the relative abundance of individuals among different species are similar
how to compare species diversityof areas?
a rank-abundance graph
is the SHannon weiner value a number of species?
no
what is a problem with the Shannon Weiner index?
highly sensitive to sample size and standardization
what does the Hill shannon number mean?
the number of equally common species
what is Hill Simpson?
index for the probability that two randomly selected individuals will not be of the same species
what are ways to standardize?
Take the same amount of samples, individuals or coverage. Individuals is not advised.
WHy is Hill Shannon or Simpson better than Shannon Wiener?
standardization doesn’t matter
what can you tell from a rank abundance graph?
relative species abundance, and also evenness and dominance
