Unit 2: The Living World: Biodiversity

Notes

Biodiversity

Number and variety of organisms found within a specified geographic region or ecosystem
Variability among living organisms (within/between species/ecosystems)
bioD in all forms is the result of evolution

Evolution

Change in a population's genetic composition overtime

Phylogenetic trees model evolution

Speciation: how new species are formed
Species: group of organisms that are capable of breeding with one another
Evolutionary fitness: individual organisms better adapted for their environment live and reproduce → their genes are part of their population’s next generation
Natural selection: habitat selects certain organisms to live and reproduce and others die

Beneficial characteristics that can be inherited are passed down to the next generation
Unfavorable characteristics that can be inherited become less common in population
Nat selection acts upon whole pop, not on an individual organism
Gene pool changes

Genetic drift: accumulation of changes in the frequency of alleles (versions of a gene) over time due to sampling errors (changes that occur as a result of random chance)
Microevolution: when a population displays small scale changes over a relatively short period of time
Macroevolution: large-scale patterns of evolution within biological organisms over a long period of time
Extinction: species can’t adapt quickly enough tot env change and all members of the species die

Biological extinction: true extermination of a species → there are no individuals of this species left on the planet
Ecological extinction: there are so few individuals of a species that they can no longer perform its ecological function
Commercial/economic extincion: few individuals exist but effort needed to locate and harvest them is not worth the expense

Ecosystem change

Keystone species: single species that maintains biotic balance in a community

Presence contributes to ecosystems diversity
Extinction of keystone species would lead to extinction of other forms of life

Indicator species: used as standard to eval health of an ecosystem

More sensitive to biological changes within their ecosystems than other species → used as an early warning sys to detect dangerous changes to a community

Indegenious species: originate and live or occur naturally in an area/env
Invasive species: introduced species

Ecological succession

Primary succession

If ecological succession begins in a virtually lifeless area

Secondary succession

Ecological succession that takes place where an existing community has been cleared btu the soil has been left intact
Organisms in the first stages of either primary/secondary are pioneer species (usually have wide ranges of env tolerance)

Climax community

Final stage of succession
Dynamic balance b/t a/biotic components of the community

Ex. deciduous forest ecological succession

Bare rock
Lichen, algae, mosses, bacteria (break down rock and leave organic debris which forms soil)
Grasses (add organic matter to soil and anchor it in place)
Small herbaceous plants (continues to add organic matter to soil)
Small bushes (add shelter and shade for other plants)
Conifers (create additional habitats)
Short-lived hardwoods such as dogwood/red maple (tolerates shade of conifers but are short lived and vuln to damage)
Long-lived hardwoods (more specialized, hardier hardwoods such as oak and hickory)

Island biogeography

Habitat fragmentation: when the size of an organism's natural habitat is reduced
Ecotones: where ecosystems meet at wide and overlapping boundaries

Edge effect: at ecotones, greater species diversity and biological density than there is in the heart of ecological communities

Theory of island biogeography

Number of species found on an undisturbed island is determined by two factors: IMMIGRAITON and EXTINCTION

Loss of Biodiversity (Humans)

Activity	Explanation	Solution
Clearing land for construction, homes, roads	Reduces habitat for many species Results in habitat fragmentation	Cluster development Smart growth planning Develop urban boundaries Habitat conservation areas
Logging, clear cutting, deforestation	Reduces habitat for many species Results in habitat fragmentation	Replant trees Selective cutting
Agriculture Monoculture/GMOs Clearing forests to create pastureland Pesticide use	Eliminates native species; decreases genetic variation Reduces habitat for many species Eliminates native species and beneficial organisms	Encourage polyculture, agroforestry, intercropping Require GMO crops to be sterile Create wildlife, habitat corridors Grow shade-tolerant crops Implement IPM techniques, biological pest controls
Overfishing, hunting, overhunting, poaching	Reduces keystone species Reduces top predators Depletes endangered species	Regulate activities Establish quotas Enforce existing laws (ESA) Ban trade (CITES)
Water contamination by Excess fertilizer Runoff from feedlots Runoff from construction Untreated sewage	Overloads sediments and nutrients Decreases dissolved O2 (only certain species can survive)	Regulate non-point sources of water pollution (ex. Buffer zones, swales, containment ponds, stormwater treatment areas) Secondary or tertiary treatment
Burning of fossil fuels	Climate change: death of coral reefs, loss of reef habitat, increases sea level with resulting loss of coastal habitat Acid rain: increases acidity of freshwater systems (only certain species can survive)	Climate change: implement the kyoto protocol, carbon sequestration, carbon cap and trade, carbon tax, switch to renewable energy sources Acid rain: require scrubbers on coal burning power plants, switch to renewable energy sources
Introduction of invasive species	displaces native species	Checkpoints for agricultural inspections Tighter enforcement on import of horticultural or exotic species Edu regarding strategies to prevent invasives
Dams/hydroelectric plants	Fragments habitat	Steps to allow fish migration
Surface mining	Destroys habitat	Enforce surface mining and reclamation act

Threatened and endangered species

Threatened: number of individuals in a species is quite low
Endangered: species in imminent danger of going extinct

Most endangered: require large ranges of habitat to survive, hae low reproductive rates, have specialized feeding habits, low pop numbers

Background extinction rate: natural rate of extinction
bioD hot spot: highly diverse region that faces severe threats and has already lost 70% of its original vegetation
Humans

Poverty and rapid pop growth cause ppl to use destructive practices (ex. Slash and burn farming destroys species’ habitats)
Building roads and cities- habitats are fragmented and lost
Invasive species, direct hunting, overexploitation

Solutions

Living sustainably and conserving resources → lower demand that destroy habitats
Making it illegal to trade in specific organisms → not hunted or collected
Zoos have captive breeding programs where endangered species are bred under human control until their pop are high enough to be reintroduced into the wild
Conserver habitats by req that large tracts of land be set aside and protected from human activity → organisms can find their niche and survive without risk of human interference (ex. National parks, animal sanctuaries)

Causes of extinction (HIPPCO)

Habitat destruction/fragmentation
Invasives
Population
Pollution
Climate change
Overharvesting

Date	Law	What It Did
1972	Marine mammal Protection Act	Protected marine mammals from falling below their optimum sustainable pop levels
1973	Endangered Species Act Program for the protection of threatened plants and animals and their habitats	Prohibited the commerce of those species considered to be endangered or threatened
1973	Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES)	Bans capture, exportation, sale of endangered and threatened species