Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Biodiversity Chapter 13.

Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.

Biodiversity

Chapter 13


Outline:

• Biodiversity and Species Definitions• Benefits of Biodiversity• Threats to Biodiversity

Human Caused Reductions• Biodiversity Protection

ESA- Minimum Viable Populations

CITES• Captive Breeding


BIODIVERSITY AND SPECIES

• Biodiversity Types: Genetic Diversity - Measures variety of

different versions of same genes. Species Diversity - Measures number of

different kinds of organisms within a community.

Ecological Diversity - Measures richness and complexity of a community.


What Are Species

• Species - Organisms of the same kind that are able to breed in nature and produce fertile offspring. Underlying idea is that reproductive

isolation prevents gene exchange and gives rise to new species.

- Hybridization creates a dilemma. Species identification often based on

morphological characteristics. DNA sequencing


How Many Species

• Currently 1.4 million species identified.• Estimates range between 3-50 million.

May be 30 million insect species. May be 10 million species on ocean floor. Invertebrates make up 70% of all known

species, and probably most of yet to be discovered species.

• Tropical rainforests and coral reefs are biodiversity hotspots. NA and Europe only contain 10-15%.


BENEFITS OF BIODIVERSITY

• Food As many as 80,000 edible wild plant

species could be utilized by humans.• Drugs and Medicines

More than half of all prescriptions contain some natural product.

Pharmaceutical companies actively prospect tropical countries for products.


Benefits of Biodiversity

• Ecological Benefits Soil formation, waste disposal, air and

water purification, nutrient cycling, solar energy absorption, and biogeochemical and hydrological cycles all depend on biodiversity.

- Can a system function without all its integral parts ?


Benefits of Biodiversity

• Aesthetic and Cultural Benefits Cultural diversity inextricably linked to

biodiversity. USFWS estimates Americans spend $104

billion annually on wildlife-related recreation.

Ecotourism can be an important form of sustainable economic development.

Existence (intrinsic) value.


THREATS TO BIODIVERSITY

• Extinction - Elimination of a species. Normal process

- In undisturbed ecosystems, background rate appears to be one species per decade.

In this century, human impacts have accelerated that rate, causing perhaps hundreds to thousands of extinctions annually.


Natural Causes of Extinction

• Fossil Record suggests more than 99% of all species ever in existence are now extinct. Most went extinct before humans arrived.

- End of Cretaceous - Dinosaurs and 50% of existing genera disappeared.

- Permian period - Two-thirds of all marine species and nearly half of all plant and animal families died out.


Human-Caused Reductions in Biodiversity

• Habitat Destruction Biggest reason for current increase in

extinction is habitat loss.- Habitat fragmentation divides

populations into isolated groups vulnerable to catastrophic events.

• Hunting and Fishing Over-harvesting of game species.

- American Passenger Pigeon- Whales


Habitat Fragmentation - Cadiz Township, WI


Human-Caused Reductions in Biodiversity

• Commercial Products and Live Specimens Wildlife smuggling is very profitable.

- Leopard fur / Rhinoceros horns US Annual pet trade in wild species:

2 million reptiles 1 million amphibians and mammals 500,000 birds 128,000 tropical fish (often caught

with cyanide above coral reefs)


Predator and Pest Control

• Many animal populations have been greatly reduced or exterminated because they are regarded as dangerous to humans or livestock. Animal control costs $20 million in federal

and state funds annually.- 700,000 birds and mammals annually.

100,000 coyotes



• Exotic Species Introductions Exotic organisms - Organisms introduced

into habitats where they are not native.- Biological Pollution

Kudzu Vine Purple Loosestrife Zebra Mussels Asian Long-Horned Beetles



• Diseases When a disease is introduced into a new

environment, natural balance may be tipped, leading to an epidemic.

• Pollution Toxic Pollutants

- Pesticides- Lead

• Genetic Assimilation


BIODIVERSITY PROTECTION

• Hunting and Fishing Laws By 1890’s, most states had enacted some

hunting and fishing laws. General idea was pragmatic, not aesthetic

or moral preservation.


Endangered Species Act

• Established in 1973. Endangered are those considered in

imminent danger of extinction. Threatened are those likely to become

endangered, at least locally, in the near future.

- Vulnerable are those that are naturally rare or have been locally depleted to a level that puts them at risk.



• ESA regulates a wide range of activities involving Endangered Species: Taking (harassing, harming, pursuing,

hunting, shooting, killing, capturing, or collecting) either accidentally, or on purpose.

Selling Importing into or Exporting out of the US Possessing Transporting or Shipping



• Currently, US has 1,500 species on its Endangered and Threatened lists, and about 500 candidate species waiting for consideration. Number reflects more about human

interests than actual status.- Invertebrates make up 75% of all

species, but only 9% of T/E list. Listing process is extremely slow.


Recovery Plans

• Once a species is listed, USFWS is required to propose a recovery plan detailing the rebuilding of the species to sustainable levels. Total cost of all current plans = $5 billion.

• Opponents have continually tried to require economic costs and benefits be incorporated into planning.


Private Land and Critical Habitat

• Eighty percent of habitat for more than half of all listed species is on non-public property. Supreme Court has ruled destroying

habitat equates to taking.- USFWS has been negotiating Habitat

Conservation Plans (HCP) with private landowners.

Landowners allowed to harvest resources as long as species benefit.


Reauthorizing ESA

• ESA officially expired in 1992. Proposals for new ESA generally fall into

two general categories:- Versions that encourage ecosystem and

habitat protection rather than individual species.

- Safe Harbor policies that allow exceptions to critical habitat designations.

(Economic Considerations)


Minimum Viable Populations

• Minimum Viable Population is the minimum population size required for long-term viability of a species. Island biogeography - Small islands far

from a mainland have fewer terrestrial species than larger, closer islands.

- MacArthur and Wilson proposed that species diversity is a balance between colonization and extinction rates.


Minimum Viable Populations

• Diversity Loss in Small Populations: Founder Effect

- Few individuals start a new population. Demographic Bottleneck

- Few individuals survive catastrophe. Genetic Drift

- Random reduction in gene frequency. Inbreeding

- Mating between related individuals.


Habitat Protection

• Latest management strategy is preservation of ecosystems supporting maximum biological diversity rather than species-by-species approach. Gap Analysis - Conservationists and

wildlife managers look for unprotected landscapes that are rich in species.

- Broad-scale, holistic approach.


Biodiversity Map


International Wildlife Treaties

• Convention on International Trade In Endangered Species (CITES) - 1975. Regulated trade in living specimens and

products derived from listed species.


CAPTIVE BREEDING

• Breeding programs in zoos and botanical gardens are one method of saving threatened species. Repositories of genetic diversity.

- Most mammals in NA zoos are now produced from captive-breeding programs.

Some zoos now participating in reintroduction programs.


Captive Breeding

• Zoos have limited space for captive breeding. How many can / should we save ? Ultimate problem is that natural habitat may

disappear while we are conserving the species itself.

• Another alternative is to attempt to save species in the wild. Provide funding for protection in native

habitats.


Summary:

• Biodiversity and Species Definitions• Benefits of Biodiversity• Threats to Biodiversity

Human Caused Reductions• Biodiversity Protection

ESA- Minimum Viable Populations

CITES• Captive Breeding

Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Biodiversity Chapter 13.

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Transcript of Cunningham - Cunningham - Saigo: Environmental Science 7 th Ed. Biodiversity Chapter 13.