Ecology: Organisms and their Environment

Question 1

Populations

Answer 1

• -members of a sp that live in a defined geological space

- -studied based on density and dispersion

Question 2

Communities

Answer 2

• -collection of all pop’s of all the species within the same defined geological space
• -predatory prey, competition, mutualism

Question 3

Ecosystems

Answer 3

• -ecological community with the surrounding physical environment
• -separate related parts function together as a whole
• -has biotic and abiotic material
• -abiotic: air, water, rocks, soil
• -biotic: plants and animals
• -influenced by internal and external factors
• -biodiversity: measure of ecosystem health
• -living community of organisms and abiotic components

Question 4

Biomes (Aquatic)

Answer 4

• -largest ecosystems on Earth
• -dominant form of plant life and groups of animals
• -similar climates and sp found within them have shared characteristics
• -aquatic, terrestrial, marine

ocean biome divided in layers

• -benthic (bottom)
• -pelagic (open ocean)
• -photic (top layer): where life undergoes photosynthesis, phytoplankton (base of food chain)
• -coast: lots of life and diversity of life

coral reef: coral (invertebrate), secrete calcium carbonate as its exoskeleton

• -coral polyps
• -algae
• -bacteria and fungi
• -fish

estuary: ocean biomes meet freshwater
- -constant water flow
- -diversity of life
- -phytoplankton and detritus serve as nutrients for consumption by zooplankton
- -ocean organisms and birds

wetlands: terrestrial area covered in water
- -supports aquatic vegetation
- -food chain rooted in nutrient rich detritus, supports diversity of life
- -supports permanent, migratory, ephemeral (short time), and transitional
- - bogs, swamps, marshes

streams: freshwater flows from headwater source to ocean
- -headwaters :higher oxygen, therefore more life

ponds and lakes:

• -photic zone
• -profundal zone: dark, few life
• -littoral zone: productive, shallow, near waters edge, supports vegetation (phytoplankton and rooted plants)

Question 5

Biomes cont. (Terrestrial)

Answer 5

share similar climates and environments, sometimes latitude and geographic location

tundra (poles): flat, treeless land, mosses, lichens, grasses shrubs

• -layer of permafrost (prevents water drainage)
• -harsh cold, wet, windy
• -crane flies, caribou, artic hares, lemmings

alpine: worlds mountains (10,000 ft or higher)

taiga: south of Artic tundra, is the northern boreal forest
- -northern hemisphere
- -conifers: spruces, firs, pines
- -artic hare, caribou
- -insects, small mammals, large animals (moose, wolves), migratory birds

temperate deciduous: Eastern US,

• -trees with leaf loss and regrowth with seasonal changes
• -forests with vertical stratification
• -tops of tallest trees form canopy that shield lower canopy, understory, shrub layer, ground
• -forest stratification, richer soil, and less harsh environ lead to greater diversity of life like reptiles and amphibians

grassland: grass sp adapted to rainfall, periodic fires, flat terrain
- -invertebrate and vertebrate
- -large grazing animals and burrowing rodents
- -very fertile soil

savanna: tropical grassland, soil poorer in nutrients
- -drier, warmer, flatter

desert: low rainfall, high evaporation
- -cold temperate or hot weather
- -shrub like, scattered plant life like succulents and sagebrush
- -plants and animals adapted to dry conditions only flowering or exiting dormancy during rain

chaparral: dry summers and wet winters
- -shrubs (small woody plants)
- -complex animal life dependent on shrub stratification

tropical rain forests: very productive biome

• -half of worlds plant and animals sp
• -close to equator
• -adequate rain
• -series of stratified layers that create microclimates that support many sp
• -soil has little nutritional value due to efficient decomposers

Question 6

Habitat and niche

Answer 6

• -habitat: physical location where organism lives

- -niche: organisms role, includes all biotic and abiotic factors that influence organism

Question 7

Competition and predation

Answer 7

• -predation (predatory and prey)
• -essential for energy transfer and pop numbers and growth
• -pop size of one sp is dependent on presence, abundance, and absence of another
• -niches overlap in terms of food resources, similar habitats, and feeding behavior, competition emerges
• -interspecific competition: for food, water, space bw 2 diff sp
• -competitive exclusion principle: one pop. will outcompete another when vying for same limited resource and other pop goes extinct
• -however, coexistence has occurred due to resource partitioning (using resources at diff times, ways, or locations)

Question 8

Exponential growth

Answer 8

• -growth rate of a pop. that increases at consistent pace
• -rate of growth is proportional to number of individuals in a pop.
• -J shaped growth curve, gets steeper with time
• -assumes resources in an environment are constant and unlimited

Question 9

Logistic growth

Answer 9

• -S shapes curve
• -pop. begins to grow at exponential rate
• -as limiting factors impact, pop and resources become scarce
• -pop. grows at slower rate/ decreases
• -growth curve will level off and become stable
• -pop has reached max size and density that geographic area can support (carrying capacity)

Question 10

Sexual and Asexual

Answer 10

asexual: arise from single parent
- -great number of offspring within short period of time
- -pop grows quickly and exploits environ
- -loss of genetic variation

sexual: fusion of gametes from 2 distinct parents
- -greater genetic diversity
- -must balance resources to produce and raise offspring

Question 11

Parental investment

Answer 11

• -amount of time and energy parent expends to support offspring that has neg. impact on parent ability to invest in his or her own biological fitness
• -amt of parental investment is inversely proportional to number of offspring
• -reduces parents fecundity: ability to produce offspring
• -but increases offspring chance for survival

Question 12

Number of offspring produced vs. number that survive

Answer 12

–opportunistic sp: small in size, short life cycle, large number of offspring in short time, no resources put into offspring, high mortality rate

–equilibrium sp: fewer offspring produced, great care for offspring, longer life span

–constant loss sp: moderate amt of offspring, constant mortality rate throughout lifespan

Question 13

Symbiosis (bw 2 dissimilar sp)

Answer 13

–Parasitism: parasite and host, parasite quickly reproduces, relies on host for food and for reproductive cycle

–Commensalism: little to no effect on host

–Mutualism: both benefit, many cases they coevolved together each adapting to changes and adaptations in the other, develop interaction thru evolution

Question 14

Competition and territoriality

Answer 14

• -competition for resources can lead to territoriality
• -happens when populations occupy same habitat or niche
• -leads to increased access to resources to promote reproduction and success among that winning pop.
• -other organisms have to relocate to place with fewer resources

Question 15

Altruistic behaviors

Answer 15

• -series of behaviors that benefit another organism at the cost of the organism that is displaying the behavior
• -organism does to benefit pop as a whole
• -prevalent among sp with high levels of parental investment or in pops that have complex social behavior
• -examples include:
• -aiding weaker of injured member
• -group defense mechanisms
• -closely tending and protecting offspring

Question 16

Primary vs secondary succession

Answer 16

• ecosystems and habitats are always evolving due to internal and external factors
• -process of ecosystem change and development over time

primary succession: occurs on substrates that have not been colonized or inhabited by life before
–soil has little nutrients

secondary succession: occurs in areas that once had life, but starting anew after a major environmental disturbance
–are good nutrients in soil due to previous life

Stages of Ecological Succession
--pioneer plant stage
\:photosynthetic microbes or plants adapted to living in areas with little resources 
\:small, reproduce quickly
\:invertebrates soon follow

--intermediate species
\: as organisms die and decompose they add nutrients to soil to support great complex diverse plants
\:grasses and shrubs
\:reproduce more slowly
\:more diversity and biomass
\: take advantage of new habitats

–climax community
:previous organisms die and decompose which enriches soil and supports bigger complex plants
:stable, mature plant growth
:dominated by few species well suited for habitat
:greatest diversity, biomass, and productivity
: exist in equilibrium
: however natural or human caused events arise, if this occurs secondary succession would begin in the area

Question 17

Biomass, diversity, productivity, and habitat changes during succession

Answer 17

Applicable to Ecosystems in General

• -each stage marked by major change in nutritional value of soil and development of diff dominant forms of vegetation
• -as vegetation changes the diversity of other forms of life change and increase
• -results in biomass accumulation (total number of organisms)
• -increase in ecosystem productivity
• -with each change, more productivity and biomass and stability

Question 18

Trophic Lvls

Answer 18

1. primary producers (plants), bacteria, algae, plant like protists
   - -have greatest amt of biomass
2. primary consumers (herbivores or omnivores)-heterotrophs
3. secondary consumers (carnivores or omnivores)
4. tertiary consumers (carnivores)
5. quaternary consumers (carnivores)

• -decomposers: does not have own trophic level
• -consumes detritus
• -breaks down organic into inorganic

Question 19

Food webs

Answer 19

• • complex chain of energy transfer in ecosystem composed of multiple food chains which is series of organisms each dependent on the next for source of food
• -encompass all individual food chains and feeding relationships

Question 20

Water cycle

Answer 20

• hydrologic cycle
• -moves thru biotic and abiotic pathways
• -closed system: amt of water on Earth does not change
• -evaporation: liquid water to vapor
• -transpiration: water in biotic matter vaporizes and returns
• -condensation: water vapor into atmosphere
• -precipitation: vapor rises, meets cooler temps and becomes liquid in form of atmospheric clouds, these grow and release their water
• -goes to oceans, evaporates back into atmosphere, groundwater or into rivers, lakes, or streams

Question 21

Carbon cycle

Answer 21

• -within atmosphere, oceans, land, sediments and rocks
• -most essential element
• • moves thru biotic and abiotic

atmosphere: gas form as CO2 and methane
oceans: greater amt here, dissolved CO2
land: within organisms and soil
sedimentary: largest amt here, carbonate rocks, volcanic eruptions, fossil fuels

• -carbon exits abiotic and enter biotic via plants
• -carbon continues in biotic pathways as organisms consume it produced by plants
• -animals undergo cellular resp. which returns carbon as CO2
• -rest of carbon stored in organism and released when dies
• -some C back to atmosphere or will join sedimentary rock as fossil fuels
• -fossil fuels are burned, CO2 is released into atmopshere and intensifies greenhouse effect

Question 22

Nitrogen cycle

Answer 22

• -in atmosphere, 78%
• -organisms can not access N in its pure form therefore:

Nitrogen fixation

• -nitrogen fixing bacteria
• -break down nitrogen gas and convert to ammonia during ammonification

Nitrification

• -ammonia into into usable cmpds by bacteria and archaea
• -converted into nitrate
• -nitrate taken up by plants in nitrogen assimilation

Dentrification

• -nitrogen stays stored in plants until dies/decomposes and returns nitrate to soil
• denitrifying bacteria convert nitrate back to nitrogen gas
• -nitrogen gas back to atmopshere
• -nitrate can leach/ runoff

Question 23

Phosphorous cycle

Answer 23

• -sedimentary cycle
• -doesnt exist in atmosphere
• -abiotic pathway in earths minerals and sedimentary rock
• -phosphates in rock are released into soil thru weathering by wind and water
• -phosphorus in rock enters soil as minerals as salts
• -salts dissolved in water, return biotic pathway as plants assimilate mineral and convert from inorganic phosphorus to organic phosphorous
• -organic phosphorus consumed
• -organisms die and its returned to soil
• -P settles down and becomes stored in sedimentary rock in bodies of water
• -at this point it becomes lost, this means P is limited

Question 24

Temporal and spatial disturbances

Answer 24

temporal (time and freq)
spatial: size and structure

• -some disturbances small and frequent or large and frequent
• -can be unpredictable
• -some over long periods of time or large changes suddenly

–major disturbances lead to deforestation, habitat destruction, population mortality, relocation of sp

Question 25

Fragmentation of ecosystems

Answer 25

• -natural and human disturbances break up habitat into small isolated fragments
• -leads to less resources
• -impacts ecosystem health
• -more competition and loss of population
• -isolating from reproducing pops of same sp decreases genetic variation
• -difficulty to adapt

Question 26

Natural Ecosystem Recovery

Answer 26

–speed and ability of ecosystem to regain pop numbers and species and species diversity after a disturbance

Dependent on Factors

• -frequency of disturbance
• -size of disturbance
• -size and distance among fragmented habitats
• -scale of disturbance

Question 27

Pollution

Answer 27

• -artificial or natural contaminant
• -makes resources unsafe for use or consumption
• -water and soil polluted by pesticides or chemical fertilizer runoff, leaches into soil or carried by water
• -drinker water contaminated or food chain thru bioaccumulation
• -bioaccumulation: organism intakes pollutant faster than than it loses it thru metabolism or excretion
• air pollution via industry, transportation, agriculture
• -alters chemical comp. of atmosphere, creates new pollutants
• -smog: fog and smple
• -photochemical smog: rxn bw sun, hydrocarbons, and nitrous oxide

greenhouse effect: gases trap thermal energy emitted by Earths surface, this radiates heat absorbed by sun, this affect temp of Earths atmosphere

greenhouse gases: CO2, methane, nitrous oxides

chlorofluorocarbons: human produced, include carbon, fluorine, and chlorine
- -break down org. cmpds and react with atmospheric gases
- -chlorine reacts with ozone and destroys it, converts it to oxygen

acid precipitation: air pollutants such as sulfur dioxide and nitrogen dioxide mix with water vapor to form sulfuric and nitric acids

• -this falls back as rain, snow, etc
• -reduced soil ability to support great numbers and biodiversity
• -also impacts water chemistry leading to loss of life and biodiversity

Question 28

Habitat Destruction

Answer 28

–deforestation: clear cutting of forest for agricultural use or urban sprawl

–agriculture: majority of human caused deforestation

• -desertification: soil degradation and loss due to deforestation and agricultural mismanagement
• -inhospitable to many forms of life

Question 29

Introduced Species

Answer 29

• -loss of species diversity as result of introduction of non native species
• -brought intentionally or accidentally

invasive species: introduced sp that have neg impact on human or ecosystem health

• -cause disruptions in food chain bc prey on native sp, and outcompete them for resources
• -alter ecosystem, make unsuitable
• -diseases

reintroduced species

• -pos impact
• -release of once common sp
• -sp whose pop. declining
• -introduce greater genetic diversity
• -obtain ecosystem balance

Question 30

Remediation

Answer 30

–removing or extracting contaminants from pollluted areas (water, soil, air)

-oil spill remediation: trap and contain water based oil spills

Question 31

Natural Flow of Material Bw Ecosystems

Answer 31

Nutrient cycling

• -flow of energy and nutrients within a single ecosystem/ bw ecosystems
• -P, C and N flow from abiotic to biotic sources and back again
• -includes plants and animals flowing in and out

–the more similar the diff ecosystems are in structure and fn the greater
exchange of materials

–less well defined and distinct an ecosystem the greater the chance the sp will regain resources

Question 32

Transport of materials by humans

Answer 32

• -agricultural activity
• -diff sp introduced
• -native sp reduced or eliminated
• -rare sp begin to exist
• -humans move abiotic material
• -we alter soil comp and chemistry
• -alter water resources and access to substrate

Question 33

Movement of organisms

Answer 33

–migration (immigration or emigration)

Occurs Bc

• -adapt to changing or cyclical resource availability
• -find new reproductive partners
• -inc genetic variation
• -use particular resources

Question 34

Resource availability and abiotic factors

Answer 34

• -influences size of pop.
• -ecological resource is object or material that organisms need to grow, develop, and thrive
• -can be biotic or abiotic
• -food, water, light, nutritious soil and land for shelter and territory influence pop. size