Mechanisms of Species Loss Fri. Feb. 11

Biodiversity Intactness Index

R = richness of a particular taxon in a particular pristine habitat type

A = area of pristine habitat of various types

I = expert opinion of impact of a particular type of land use in each habitat type

Thus RA = richness for a particular taxon in pristine habitat types under consideration

RAI = richness in same habitat types that have been degraded.

Mechanisms of Anthropogenic Extinctions

Note the "big four" (my term) anthropogenic factors:

• Habitat loss/degradation• Pollution• Overexploitation• Invasive species

Bio-magnification of Toxins

Cascading Effect

of a Non-Native

Pathogen

Notice that the effects start with tree loss and then spread to alter both the plant and animal parts of the community and aspects of the physical environment.

Phytophthora: http://en.wikipedia.org/wiki/Phytophthora

Factors that Put Species from Different Taxa

in Peril

Endangered Miami Blue Butterfly (top) Larval rearing (below)

http://www.nps.gov/bisc/parknews/images/Miami-Blue-butterfly-larvae.jpg

http://www.floridastateparks.org/bahiahonda/images/visitors/BAH-MiamiBlueButterfly-MichelleWisniewski.jpg

Where Are Most Threatened Vertebrate Species?

The bar indicates # of species and the black portion indicates numbers that are considered threatened.

Rankings of Countries by Known Threatened Species

Extinction Threats in the USA

Each bar refers the percent of known USA species of that taxon that are considered threatened.

USFWS Lists over 1250 species as endangered (mostly plants); most of these are on the Red List.

Some have estimated that about 1/3rd of US species are at risk of extinction.

Types of Threats of US Species, by Taxon

In most groups, habitat loss is the most important factor leading to threat.

Causes of Threat in China

Note the differences with the USA – exploitation is more of a problem and invasive species are less of one.

Rarity: Population Size, Range, and Specialization

Measuring Threat and Degradation

The International Union for

the Conservation of Nature

Probably the most important conservation organization on the planet. Among other things, the IUCN compiles the most respected lists that report the conservation status of various species ("Red List").Please note that links to many other organizations and resources

can be found on the class's homepage.

What is the IUCN "Red

List"

Initiated in 1963.•A nine category list

•The threatened categories are often what people consider when they talk about the Red List, but it is much more.

• Rigorous scientific criteria are used for classification of a species in the Red List scheme.

• Every effort is being made to be as inclusive and transparent as possible – inclusive so that species can be effectively monitored over time, even if not presently "of concern."

http://www.iucnredlist.org/static/introduction