Conservation Biology

1. Conservation Biology: Biology Population decline & scarcity

            2-Separate Approaches

                        1.  The small-population paradigm

                        2.  The declining-population paradigm

2. I) Small Population Paradigm – Extinction vortex

            -Population genetics & demographic models extinction

            -Key maintenance of genetic variability

            -Conservation Biologists interested determining Parameter MVP:

Minimum Viable Populations (MVP)

Rare species maintain populations if at some minimum size

-Extinction caused by chance events:

Demographic stochasticity – random birth & death rates

Genetic stochasticity – better > heterozygous loci fitness

Environmental stochasticity – variance > growth rate

-Prairie chicken decline central Illinois 1970-1997- small populations

Decline associated with loss of genetic diversity

-Small population paradigm in conservation biology

            Theoretical base in population genetics

            Useful for conservation biologists

            Not going to solve the problem of small populations

3. II) The Declining Population Paradigm:

            -Focus ways detecting, diagnosing, halting pop. decline

            -Problem viewed in a demographic terms, rather just genetic

            -Action oriented (prevention)

            -Not concerned with the population #s rather trend decrease

            -Most declines are not “chance events”

            -Deterministic extinctions vs stochastic events

            -4 most important causes of deterministic extinctions:

Overkill

Habitat destruction & fragmentation

Introduced species

Chains of Extinction

1.  Overkill

            -Fishing or hunting rate exceeds pop. capacity rebound

            -Large spp. low r (elephant 10yrs mature 1calf @3-9yrs)

            -Valuable to humans – classic example elephant ivory trade

2.  Habitat destruction & fragmentation

            -Example: Pine savannas red-cockaded woodpecker

                        -Feed under pine bark insects nest cavities

                        -Life history woodpeckers complex behavior

                        -Most important utilize pre-existing cavities nesting

                        -Conservation efforts focused on providing cavities

                                    remove flying squirrels & genetic exchange

            -One major problems: Humans created agricultural/urban landscapes

                        Most wildlife cannot be supported on this habitat type

            -Habitat Fragmentation Potential Effects on Population Dynamics

            -Not all species see fragmentation same:  Very Species-specific

                        -Wide-ranging species (birds) not see fragmentation problem

                        -Patch-ranging species see edges as boundaries

            -Islands good model systems analyze extinction function area (patch)

-Conservation Biologists interested in increasing genetic variability limit extinction islands

-Need promote movement or immigration between patches fragmented landscape

            -Various ideas of corridors or stepping stones

            -These have advantages & disadvantages (controversial at present)

            -Do animals use corridors?

3. Introduced species – cause extinction

Example: Australia medium sized mammals (red fox prey)

4. Chains of Extinctions – cause secondary extinctions

Animals (plants) dependent obligate on another species

Host-parasite relationships

Predator-prey (forest eagle New Zealand ground birds)

Black-footed ferret vs prairie dogs

Humans & ? (trees oxygen) how much loss is sustainable?

4. Approach to Preserve Total Loss of Biodiversity Earth

Nature Reserves (National Parks & Biosphere Reserves)

                        -Various approaches that conflict

-To conserve specific animals & plant communities through Management.

-To allow system exist in “natural state” no attempt manage for specific species.

-Problem with reserves have to define what want out of the effort:

            -Conflicting ideas based on mandates one agency to another

            -Needs for managing one spp. does not sustain another

            -Grizzly bears MVP of 500 need area 12xs current park size

-Currently: -6-7% Earth’s land protected (?) most areas small

5. Example Conservation Problems: US-Northern Spotted Owl

            -Practical (economic) question: How much fragmentation can owl take?

6. Summary:

-Conservation Biology focused on rare & declining species

-Small populations subject stoichastic events extinction

-Declining populations establish cause & effect avoid extinction

-Extinction is what conservation biologist trying avoid-no 2nd chance

-Solve problems need genetic, ecological, political solution

-Natural reserves are needed to protect species in entire ecosystem

-Current land use change-less natural areas > urban, suburban, agricul.

-How much natural world are we willing to lose?  or afford to lose?