Unit 2 - Biodiversity

human activity leads to disruptions of natural processes, having economic and ecological consequences
^^environmental worldviews^^: anthropocentric or ecocentric (balance is biocentric)
^^sustainable development^^: using resources in a way that fulfills human needs but does not deplete their quantity for future generations (profitable)

==Provisional==: resources directly derived from sources in nature
- most basic of all ecosystem services
- ex. water, food, plants, fuels, timber, herbal medicine
==Regulating==: processes that maintain natural phenomena to be clean, functional, and resilient
- essential for human survival; costly to replace
- ex. air/soil quality, pollination, water flow, carbon sequestration
==Cultural==: abstract concepts/ideas that contribute to the cultural/theoretical development of human society
- not a necessity for basic human survival
- ex. knowledge, sports, sense of place, aesthetics, art
==Supporting==: basic natural processes that sustain life on Earth
- the foundation of all other processes
- ex. photosynthesis, water cycle, nutrient cycle

study of ecological relationships and distributions of organisms on islands + their community structure
- created by Caral Linnaeus (1707 - 1778) Charles Darwin (1809 - 1822), Alfred Russel Wallace (1823 - 1913)
@@species richness@@: # of species in an area
@@species evenness@@: comparison of pop. of species
Robert McArthur & EO Wilson (1967)
- @@highest species richness@@: large islands near the mainland
- @@lowest species richness@@: small islands far from the mainland

physical and geographical disruption of various environments caused by human activity
- → l^^oss of apex predators^^ (ie. wolves, bears, etc.) and more specialist feeders
- → ^^increase in # of organisms of generalist feeder species^^ (can easily adapt to changes in food sources and other resources)
- limits %%migration%% for isolated species in different biomes
- human activity (agriculture and societal development) → increase in habitat fragmentation → separation of species
solution: ^^habitat corridors^^ (connecting fragmented habitats through animal-friendly tunnels or bridges = easier migration & greater diversity)

range of %%abiotic conditions%% (temperature, sunlight, salinity, etc.) that an organism can %%endure%%
- measured on a bell curve
- %%> range%% (below avg range of ecological tolerance) = reduced fitness; inability to thrive/reproduce

ecological impact of ^^natural^^ disruptions >= ecological impact of ^^human^^ disruptions
^^natural processes^^: quick vs short-term
- $periodic$ : one event → long-term effect/event
- $episodic$ : sudden event → greater effects/events over time
- $random$ : sudden, w/o leading cause

has changed over time thru %%geological shifts%%, including:
- amount of solar radiation reaching the Earth
- changes in atmospheric composition (ie. greenhouse gases, ozone layer depletion)
- rising sea levels due to melting glacial ice

^^seasonal movement^^ of animals from one habitat → another habitat
- adaptative response for %%better opportunities for resources and matin%%g
- varies greatly by the organism
- ex. birds migrate from the Northern Hemisphere → Southern Hemisphere annually

organisms adapt to their environment over time (short & long-term scales) through ^^incremental genetic changes^^, leading to:
- %%physical changes in appearance%%
- ex. peppered moths (lighter body tones → darker body tones)
- %%biochemical changes%%
- ex. pesticide resistance (mutations in the genes of pests cause pesticides to become ineffective), natural selection
adaptations persist in an organism species if it is $**advantageous**$ to their survival in the environment → reproduction to pass similar genes to offspring
gene must be present BEFORE the environmental change

sudden or gradual environmental changes → endangering lives of different species in habitat:
- changes in behavior (adaptation)
- migration
- extinction
- ex. climate change → extinction of dinosaurs, deforestation → dislocation of species
organisms with a %%selective advantage%% will be better at adapting and surviving in a new environment

a gradual process where %%community structure changes%% (typically replacement of community)
- affects the total biomass, species richness, and net productivity
- ex. changes in predominant plant community → habitat/wildlife change
- ^^biomass^^: larger plant species have more biomass than smaller plant species (material & weight)
- ^^richness^^: greater in previously distributed species; less in recently distributed species
- ^^productivity^^: more biomass → higher rates of photosynthesis (measure of productivity)
$primary succession$ : a new area is dominated by pioneer species (lichens)
- rock → soil formation & initiating plant growth
- caused by human or natural disruptions
- primary succession + adaptation over time = origin of new species
$pioneer species$ : ^^broad range^^ of ecological tolerance to survive ecological disturbances
- adaptable; can quickly pass on genetic traits; supports the emergence of new species
$secondary succession$ : new species take over old land (still filled with soil)
- also caused by human or natural disruptions
$keystone species$ : plays a significant role in ^^determining^^ community structure
- ex. otter, sea urchin, kelp
$ecosystem engineers$ : organisms that alter habitat beneficially
- ex. beavers
$mutualists$ : two organisms interact for mutual benefit
i $ndicator species$ : represents aspect or quality of an ecosystem is present
- has a ^^narrow range^^ of ecological tolerance
- ex. amphibians