Living World and Populations Review

Ch’s 4, 5, and 6

Ecology

• Ecology from big to small– Biosphere– Ecosystem- abiotic and biotic – Communities- different species living in same area

(does not include abiotic factors)– Populations- same specie living in an area– Organism- simplest unit, makes up a population

Population Dispersal

• Clumped• Random• Uniform

Ecosystem Characteristics

• Physical appearance- relative size, stratification, pop distribution

• Species diversity- # of diff speices• Species abundance= # of ind of each species• Niche structure= # of eco niches, how they

resemble or differ from eachother, species interactions

Ecological Niches

• A particular area within a habitat occupied by an organism that includes the function of that organism w/in an ecological community

Interaction among species • Amensalism- :I = one suffers and one is not effected

– Penicillium and bacteria• Commensalism- :I = one benefits and the other is not

affected– Remora and shark

• Competition- = one benefits one is harmed– Hunting

• Mutualism- = both benefit– Bees pollinating flowers

• parasitism=- = one is benefited at the expense of another• Predation- = good for one, bad for the other

– Cougar and bunny• Saprotrophism- :I = obtain nutrients from dead or decaying

materials

Keystone species

• Really important to the ecosystem– Presence contributes to the diversity of life– If they are extinct then others will follow– Examples)

• grizzly bear: transfer nutrients: capture salmon and take them to dry land

• Sea stars: prey on sea urchins, mussels, and shellfish, they are the only natural predator, if they are removed, mussel population would grow to much and damage coral reef

• Sea otters: protect kelp forest by eating sea urchins that destroy kelp roots

• Prairie dogs: create burrows that are used as safe havens for many other species

Species Diversity

• Organisms live in diff environments and are adapted to those biomes

• Aquatic- don’t spend energy on temperature regulation• Desert – succulents store water, small surface areas exposed

to sunlight• Grassland- drought resistant and grass grows our from the

bottom to regrow after being eaten• Forest- large leaves to capture scarce light• Temperate scrub forest- chapparal, small waxy coated leaves• Tundra- plants adapted to low light, small amounts of water,

low temps, grow mostly in summer

Edge effect

• Local environmental changes along a boundary or edge– Example: clear cutting allows sunlight to reach

floor of forest making the ground dryer and warmer

Biomes

• Antarctic• Benthos• Coastal zones• Coral reefs• Deserts• Freshwater wetlands• Grasslands• Hydrothermal vents• Intertidal• Ocean

• Savannas• Taiga• Temperate deciduous forest• Temperate rain forest• Temperate shrub land aka

Chaparral• Temperate woodlands• Tropical rainforests• Tropical seasonal forest• Tundra

Energy Flow

• Sun is ultimate energy source• Photosynthesis and cell respiration= know

basic functions of it!

Food webs and trophic levels

• Primary producers= autotrophs= plants– Make food/ photosynthesis

• Primary consumers= heterotrophs= herbivores– Eat plants/ cell resp

• Secondary or higher consumers= heterotrophs– Carnivores or omnivores

• Remember- arrows always go in the direction of energy flow!

Ecological/Trophic Level Pyramids

• 90% of energy lost at each level• Less than 3% of light that reaches earth is

used in photosynthesis• Aquatic ecosystem is only one that can have a

larger heterotrophic biomass• All others have more biomass on lower levels

of pyramids

Biodiversity

Diversity increasers• Diverse habitats• Disturbance • Conditions with low

variations• Trophic levels with high

diversity• Middle stages of succession• Evolution

Diversity decreasers • Environmental stress• Extreme environ• Supply limitations• Disturbance in extreme

amounts• Introduction of species • Geographic isolation

Natural selection

• Directional selection- individuals toward one end will do well

• Stabilizing selection- pays to be normal, differences do not help

• Disruptive selection- its not good to be normal, differences are selected for

Processes of natural selection

• Competition • Increase in phenotypic adaptations• Exponential increase in pop• Variations• Limited resources

Define

• Speciation • Convergent evolution • Evolutionary relay• Parallel evolution • Graduated equilibrium• Punctuated equilibrium

Major climatic periods

• Figure 4.22 – shows changes in temp in last 200 years

• Know iceages and cooling trends from 2,000,000 BCE to present

• Page 104-105

Succession

• Annual plants perennial plants and grass shrubs pines hardwood trees

• Most diversity in mid succession • Know the characteristics of the plant

communities early vs late succession

Bio Geochemical cycles

Carbon

• Major Carbon sinks:– Plant matter– Terrestrial biosphere– Oceans– Sedimentary deposits

• Marine sediments/rocks= 75,000,000 bill tons• Ocean= 40,000 bill tons• Fossil fuels= 4,000 bill tons

Carbon and Atmos.

• Released back into atmosphere through:– Cellular reparation– Decay of dead material– Burning fossil fuels– Weathering of rocks– Volcanoes– Release by warm ocean waters

Nitrogen

• Nitrogen fixation-(nitrogen) N2 (ammonia) NH3 or (nitrate ions) NO3-

• Nitrification- NH3 (oxidized )NO2- (nitrite) and NO3- (nitrate)

• Assimilation – when animals consume nitrogen based compounds

• Ammonification – nitrogen NH3 • Denitrification – Nitrates N2 (gas)

Too much Nitrogen??

• From planting legumes• Chemical fertilizers • Burning biomass• Cattle and feedlots (wastes)• Industrial proccesses

Phosphorus

• Found in rocks• Only one that is not found in the atmosphere

during any part of cycle• Released by weathering, acid rain, dissolved

into soil and taken up by plants • Key element in fertilizers• Clear cutting causes a decrease in phosphorus

in soil– Becomes limiting factor in plant growth

Sulfur

• Most if found in rocks and deep ocean deposits

• Release from weathering of rocks and gas release from vents

• Form of hydrogen sulfide ( H2S) and sulfur dioxide SO2

• Converted to SO3 and then to sulfuric acid H2SO4

Water

• Powered by solar energy• Precipitation • Evaporation • Transpiration• Condensation• Groundwater

Human activity on water cycle Human activity Impact on water cycle

Taking water from lakes and rivers Ground water depletion and saltwater intrusion

Clearing of land for urbanization/agriculture

Increase runoff and flood risk and soil erosion

Agriculture Runoff has fertilizer in it- nitrates, phosphates, ammonia

Destruction of wetlands Disturbing natural processes that purify water

Pollution of water sources Infections, cholera, dysentery

Building power plants Increased thermal pollution of water

Sewage runoff, feedlot runoff Cultural eutrophication

Population

Population ecology

• PVA- population viability analysis• Factors that affect PVA– Good conditions +– Bad conditions –– Few competitors +– Unable to migrate – – No defense mechanism –– Able to adapt +

Carrying capacity (K)

• S- shaped curve- logistic, shows a population reaching carrying capacity for the environment

• Fluctuations around Carry Capacity= pop growth slows down and begins to stabilize

Reproductive strategies

r- strategists • Mature fast• Short life• Usually prey• Too Many offspring• Not endangered• Low prenatal care• Density dependent factors are

limits• Small• Type III surv. Curve• Insects rodents

K- strategists • Mature slow• Long life• Few offspring• Pred and prey• High parental care

Survivorship Curves

• I= late loss– Low infant mortality– Death rates increase as age

increases

• II= constant loss– All age categories have

equal death rate

• III= Early loss– A lot of offspring– Death is prevalent early in

life, decrease as age increase

Human Population Dynamics

• Population change= (crude birth rate + immigration) – (crude death rate + emigration)

Human distribution patterns

• 1800= 65% lived in asia and europe• 1900= 25% lived in just europe (indus rev)

Fertility Rates

• RLF= replacement level fertility– Couple replaces themselves ( 2 kids per couple)

• MDC= moderately developed countries• LDC- less developed countries • TFR= Total fertility rate– Avg # of kids per womans lifetime– Niger = highest TFR @ 7.46 kids per woman

Rule of 70

• Doubling time= 70/rate of growth• Example– – 2% annual growth rate – Doubling time = 70/ 2= 35 years to double

Demographic transition • Stage 1- pre- industrial

– Little pop growth– Birth rates and death rates high

• Stage 2- transitional – Start of industrialization– Medical care increases– Birth rate increase, death decreases= increase growth rate

• Stage 3- industrial – Birth rate drops- death rate keeps dropping

• Growth rate slows

• Stage 4- post- industrial– Birth rates = death rates= ZPG (zero pop growth)– Standard of living higher

Impacts of pop growth

• Hunger– Poverty– Droughts– Populations surpassed Carry capacity– Political instability- mass migrations– Food exportation- sell to highest bidder