Biodiversity Concepts and Measurement

biodiversity definition

The variety of living organisms on Earth. Includes variation in the types of genes and species that comprise the communities and ecosystems that make up whole landscapes.

genetic diversity

The total number of genetic characteristics in the genetic makeup of a species.

This variation occurs at two levels: among individuals within a population and total diversity across populations.

polymorphism

heterozygosity

Species diversity

the variety of species that comprise a biological community -- the collection of species that occupy and interact in a particular location.

what are the the 3 species concepts

Phylogenetic: Smallest diagnosably-distinct cluster of individuals that show a pattern of ancestry and descent

Biological: Group of individuals that can potentially breed among themselves, but do not breed with other groups.

Genetic: Group of individuals that share less than XX% (e.g., 95%) of their genetic material with sister populations.

Species richness

the total number of unique species in a sample

evennesss

equitability among species in a sample

Simpson’s diversity index

D_S ranges between 0 and 1, with values of close to 1 representing low diversity, and values close to 0 indicating high diversity.

Shannon diversity index

Max value of H’ is ln(S), which occurs when every species in the collection has the same relative abundance (i.e., maximum evenness).

how do we count species in an area?

actual number of species, extrapolated estimate of the number of species, and rarefaction curve

how do we look at community and ecosystem diversity

trophic structure (ie trophic cascade, food web complexity)

what are gamma, alpha, and beta diversity used to measure?

spatial scales of biodiversity

what is gamma diversity

regional diversity

Gamma = Alpha * Beta

what is alpha diversity

local diversity, species per locality

what is beta diversity

turnover. beta = gamma/alpha