Ecology Exam 3

Richness

S= number of species

Evenness

E= equity of relative abundances

Inverse Simpson’s diversity index

1/D

Where D = Σpi² and pi is the proportion of individuals/biomass that are species i

Inverse Simpson’s evenness

E= 1/D/S

Probability of interspecific encounter: PIE

• P(two individuals are both species i) = pi²

• P(two individuals are the same species) = Σpi²

• P(two individuals are not the same species = 1 – Σpi²

α–diversity

Diversity within a sample

β–diversity

Turnover in diversity between samples collected at different places or times

β = γ / α

γ–diversity

Diversity within all samples

Rarefaction

Interpolates to standardize comparisons of species richness to a common number of individuals

Asymptomatc estimators

Extrapolate to estimate numbers of undetected species

Species (taxonomic) diversity

Assumes all pairs of species are equally similar or dissimilar

Phylogenetic diversity

Accounts for evolutionary history (e.g., years since divergence) and genetic (dis)similarity

Functional trait diversity

Accounts for measurable differences between species, such as body mass/size or leaf mass per area

Approaches for estimating the number of species on Earth

• Body size

• Extrapolations of direct counts

• Extrapolations of slowing rates of species identifications

8 million plants and animals

About 6 million insects

About 0.5 million plants

Less than 0.1 million vertebrates

About 2 million species undescribed

Big 5 mass extinction events

Ecosystem ecology

Studies the interactions between organisms (biotic) and their physical environment (abiotic) within a specified space and as an integrated system.

Ecosystem functions

Include the physiochemical and biological processes that occur within the ecosystem to maintain terrestrial life

Ecosystem services

The set of ecosystem functions that are directly linked to benefit human well-being