Unit 2: Biodiversity

AP Environmental Science Unit 2

biodiversity

biodiversity

the estimate of the variety of life in an ecosystem or the entire world

Ecosystem/Habitat Diversity

measures the number of different ecosystems in a geographic area

genetic diversity

the variety of different genes within a population

- more genetic diversity, the better the population can respond to environmental stressors like drought, disease, or famine

species diversity

the number of different species in an ecosystem and the evenness of the population sizes

species richness

the total number of different species found in an ecosystem

species evenness

the measure of how all of the individual organisms in an ecosystem are balanced between the different species
- balanced or dominant species

bottleneck event

an environmental disturbance that drastically reduces population size and kills organisms regardless of their genomes
- surviving pop = smaller and does not represent the genetic diversity of the original pop
- reduce genetic diversity

inbreeding

organisms mate with closely related 'family' members
- higher chance of offspring having harmful genetic mutations

ecosystem resilience

the ability of an ecosystem to return to its original conditions after a major disturbance

- higher species diversity = higher ecosystem resilience

ecosystem services

goods that come from natural resources or services/functions that ecosystems carry out that have measurable economic/financial value to humans

Ex) provisioning, regulating, supporting, cultural

Provisioning

goods/products directly provided to humans for sale/use by ecosystems

Ex) fish, hunting animals, lumber (wood for furniture/buildings), naturally grown foods like berries, seeds, wild grains, honey

- paper, medicine, rubber

Disrupted by overharvesting, water pollution, clearing land for agriculture/urbanization

regulating services

the benefit provided by ecosystem process that moderate natural conditions like climate and air quality

Ex) Trees store CO2 which reduces rate of climate change and lessen damage caused by rising sea level
- trees filter air by absorbing air pollutants which reduces health care costs for treating diseases

Disrupted by deforestation

supporting services

natural ecosystems support processes we do ourselves, makeing them less costly and easier for us

Ex) Wetland plant roots filter pollutants, leading to cleaner groundwater that we don't have to pay as much to purify
- bees and other insects pollinate our agricultural crops

Disrupted by pollinator habitat loss and filling in wetlands for development

Cultural services

revenue from recreational activities (hunting/fishing licenses, park fees, tourism-related spending) and profits from scientific discoveries made in ecosystems

Ex) tourists who pay to enter parks, spend money at local stores/restaurants, or camping fees

Disrupted by deforestation, pollution, urbanization

Two basic rules or observations of island biogeography

- larger islands support more total species
- islands closer to the mainland support more species

Larger Islands

- higher ecosystem diversity
- more available niches
- larger population sizes (more genetically diverse and more resistant to environmental disturbances)
- lower extintiocn rate

Distance to Mainland

Closer to mainland = higher species richness
- Easier for more species to migrate to island from mainland (swim/fly)

- More continual migration of individuals to the island habitat
- Frequent migration brings more genetic diversity & larger pop. size

- Inverse relationship between island distance from mainland & species richness
- The further away from mainland, the fewer species

Adaptive radiation

single species rapidly evolving into several new species to use different resources and reduce competition

ecological range of tolerance

range of conditions such as temperature, salinity, pH, or sunlight that an organism can endure before injury or death results

optimal range

range where organisms survive, grow, and reproduce

zone of physiological stress

range where organisms survive, but experience some stress such as infertility, lack of growth, decreased activity, etc

zone of intolerance

range where the organisms will die

Ex) Thermal shock, suffocation, lack of food/water/oxygen

natural disturbances

a natural event that disrupts the structure and or function of an ecosystem

Ex) tornadoes, hurricanes, asteroids,

periodic

occurs with regular frequency

Ex) dry-wet seasons

Episodic

occasional events with irregular frequency

Ex) hurricanes, droughts, fires

Random

no regular frequency

Ex) volcanoes, earthquakes, and asteroids

ecological succession

a series of predictable stages of growth that a forest goes through

primary succession

starts from bare rock in an area with no previous soil formation

Ex) moss and lichen spores carried by the wind grow directly on rocks, breaking then down to form soil

secondary succession

starts from an already established soil in an area where a disturbance (fire/tornado/human land clearing) cleared out the majority of plant life

Ex) grasses, sedges, wildflowers, and berry bushes have seeds dispersed by wind or animal droppings

pioneer or early succession species

appear first, when the ground is simply bare rock, or bare soil after a disturbance
- seeds spread by wind or animals, fast -rowing, tolerandtof shallow soil and full sunlight

Ex) moss, lichen (bare rock)
wildflowers, raspberries, grasses/sedges

mid-successional species

appear after pioneer species have helped develop deeper soil with more nutrients by their cycles of growth/death
- fast growing, larger plants that need deeper soils with more nutrients than pioneers, sun tolerant

Ex) shrubs, bushes, fast-growing trees like aspen, cherry, and pine

late-successional or climax communities species

appear last, after soil is deepened and enriched with nutrients by cycles of growth and death by early and mid-successional species
- large, slow-growing trees that are tolerant of shade and require deep soils for large root networks

Ex) maples, oaks, other large trees