global patterns and drivers of biodiversity

3 radiation events (rapid expansions of biodiversity)

• Cambrian explosion (542 mya)

  • all major body forms: bilateral symmetry, skeletons, compound eyes, appendages, etc.

• Silurian radiation (440 mya)

  • vascular plants

• Triassic radiation (251 mya)

  • most modern fauna: corals, amphibians, reptiles, birds, and mammals

5 mass extinctions prior to now

1. ordovician (86% of species)

2. devonian (75% of species)

3. permian (96% of species)

4. triassic (80% of species)

5. cretaceous (76% of species)

Buffon’s Law

Different species perform similar ecological roles in different places

ecoregion

Units of land containing distinct assemblages of species, with boundaries that approximate original extent of communities prior to major land-use change. 867 terrestrial ecoregions are recognized, and often used as units of management by conservation organizations

biodiversity hotspot

A defined geographic area with particularly high levels of biodiversity, which is also threatened by human activities

what are evolutionary drivers of biodiversity?

mutation, recombination, speciation, natural selection, genetic drift

what are ecological drivers of biodiversity

adaptive radiation, competition, predation and disturbance, dispersal and colonisation

allopatric speciation

form of evolutionary speciation, occurs when a physical barrier divides a population, and the divided populations diverge in genotype and phenotype.

genetic drift

Changes in allele frequencies from one generation to the next, resulting from random chance.

genetic bottleneck

Extreme change in genetic and phenotypic makeup of a species that occurs when the size of a population is severely reduced.

Founder effects

Extreme change in genetic and phenotypic makeup of a species that occurs when a small group establishes a new colony

Competitive Exclusion principle

No two species can coexist when using the same resource, at the same time, in the same location.

adaptive radiation

The evolutionary diversification of a group of organisms into forms that fill different ecological niches in an environment.

rapid evolution

Evolution by natural selection (or drift) that produces new species over the course of just a few generations.

how does predation and disturbance affect biodiversity using the example of mortality events

Mortality events increase biodiversity only when they promote life-history trade offs that allow species to coexist through niche differences. Otherwise, they decrease biodiversity.

What do we use for Dispersal and Colonization modeling

Dependent variables

I = immigration rate (species per time)

E = extinction rate (species per time)

Independent variables

P = total number of species on mainland

S = species richness of island

D = distance of island from mainland

A = area of the island

Parameters

c = colonization probability

q = extinction probability

f = scaling factor for distance

m = scaling factor for area