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 $<strong>advantageous</strong>$ 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