Download presentation
1
Mechanisms of Species Loss Fri. Feb. 11
2
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.
3
Mechanisms of Anthropogenic Extinctions
Note the "big four" (my term) anthropogenic factors: Habitat loss/degradation Pollution Overexploitation Invasive species
4
Bio-magnification of Toxins
5
Cascading Effect of a Non-Native Pathogen
Phytophthora: 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.
6
Factors that Put Species from Different Taxa in Peril
Endangered Miami Blue Butterfly (top) Larval rearing (below)
7
Where Are Most Threatened Vertebrate Species?
The bar indicates # of species and the black portion indicates numbers that are considered threatened.
8
Rankings of Countries by Known Threatened Species
Note Ecuador -- remember the "coldspot" article and also what it said about plant species.
9
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.
10
Types of Threats of US Species, by Taxon
In most groups, habitat loss is the most important factor leading to threat.
11
Causes of Threat in China
Note the differences with the USA – exploitation is more of a problem and invasive species are less of one.
12
Rarity: Population Size, Range, and Specialization
13
Measuring Threat and Degradation
14
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.
15
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." What is the IUCN "Red List"
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.