Post on 24-Feb-2016
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Human footprint – A measure of the human influence globally
How and How Much?
• Estimated 83% impacted• How?– Conversion to ag and urban– Filling of wetlands and estuaries
• But, this is largely direct and easily measured indirect impacts– Atmospheric transfers– Ozone hole– No place is completely untouched
Extinction Rate
• Difficult to calculate but can be done• Natural extinction rate 0.0001%– Based on 1 sp./1 million sp./yr
• Based on changes of trackable species in the fossil record
• Can estimate future extinction rates (see Science Focus p. 188)
• Current estimate on rate 0.01 – 0.1%
Types of Extinction
• Local – lost from one part of its range
• Ecological – still present but no longer plays a role
• Biological – gone
• (see Core Case Study @ start of chapter)
passenger pigeon
Extrinsic or Intrinsic Value
Species Introductions
• Same risk whether intentional or not
• New ecosystem and may fail to establish
• When successful, have a selective advantage– Competition– Predation (ability,
avoidancePurple loosestrife
Species Introductions
• New regs make it difficult to intentionally introduce
• Primary reason to introduce – biocontrol
• http://www.invasivespeciesinfo.gov/laws/publiclaws.shtml
Purple loosestrife beetle
Endangered Species Act of 1973
• Amended 1982, 1985, 1988 (Reagan Administration)
• Primary Goal: identify and protect endangered species in the US and abroad
• Determination by: National Marine Fisheries Service (marine), Fish & Wildlife Service (freshwater and terrestrial)
• Determination based on biological factors only
Endangered Species Act of 1973
• Many species in hotspots – unique ecosystems with high biodiversity/imperiled
• Once named, their habitat is protected• A recovery plan must be developed• Amendments allow for some habitat
destruction (habitat conservation plan)• About 1400 species named in US, but TNC
estimates 1/3 of US sp. at risk of extinction
Newest addition to the List
Snuffbox mussel – Epioblasma triquetra