Biotic Environment Review

APES Exam Reviews

Warmup

• Kahoot.it code 961910• APES Population and Community Ecology

• Populations• Succession• Communities• Ecosystems• Food chains, webs, pyramids• Biomes• Aquatic Ecosystems

Populations

Forms of Growth

• Exponential growth starts slow and proceeds with increasing speed– J curve results– Occurs with few or no resource limitations

• Logistic growth (1) exponential growth, (2) slower growth (3) then plateau at carrying capacity– S curve results– Population will fluctuate around carrying capacity

© 2004 Brooks/Cole – Thomson Learning

Time (t) Time (t)

Popu

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Popu

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Exponential Growth Logistic Growth

Population Growth Curves IdealPopulation Growth Curves Ideal

Capacity for Growth• Capacity for growth = Biotic potential• Rate at which a population grows with unlimited

resources is intrinsic rate of increase (r)• High (r) (1)reproduce early in life, (2)short generation

time, (3)multiple reproductive events, (4)many offspring each time

• BUT – no population can grow indefinitely• Always limits on population growth in nature

Carrying Capacity• Environmental resistance = all factors which

limit the growth of populations• Population size depends on interaction

between biotic potential and environmental resistance

• Carrying capacity (K) = # of individuals of a given population which can be sustained infinitely in a given area

Limiting Factors• Carrying capacity established by limited resources

in the environment• Only one resource needs to be limiting even if there

is an over abundance of everything else• Ex. Space, food, water, soil nutrients, sunlight,

predators, competition, disease

• A desert plant is limited by…• Birds nesting on an island are limited by…

Density Effects

• Density Independent Factors: effects regardless of population density

• Mostly regulates r-strategists– Floods, fires, weather, habitat destruction, pollution– Weather is most important factor

Density Effects

• Density dependent Factors: effects based on amount of individuals in an area

• Operate as negative feedback mechanisms leading to stability or regulation of population

External Factors– Competition, predation, parasitism– Disease – most epidemics spread in cramped conditions

Internal Factors– Reproductive effects Density dependent fertility, Breeding

territory size

R vs K strategists and survivorship• Two idealized categories for reproductive patterns but really it’s a

continuum• r-selected & K-selected species depending on position on sigmoid

population curve• r-selected species: (opportunists) reproduce early, many young

few survive– Common after disturbance, but poor competitors

• K-selected species: (competitors) reproduce late, few young most survive– Common in stable areas, strong competitors

Survivorship curves• Different life expectancies for different species• Survivorship curve: shows age structure of

population1. Late loss curve: K-selected species with few young

cared for until reproductive age2. Early loss curve: r-selected species many die early

but high survivorship after certain age3. Constant loss curve: intermediate steady mortality

Perc

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Succession

Communities Change• Ecological Succession: the gradual change in

species composition of a given area over time• Species do change spatially within an area at a

certain point in time, this is zonation not succession

• 2 Types depending on start point– Primary succession: gradual establishment of

biological communities on lifeless ground– Secondary succession: reestablishment of biotic

communities in an area where they already existed

What changes occur through Succession?

1. Diversity• Starts very low in harsh conditions few species

tolerate – r selected species types• Middle succession mix of various species types –

most diverse (role of disturbance)• Climax – k selected species strong competitors

dominate

2. Mineral Cycling• Pioneer, physical breakdown & make organic,

Later processing increase – cycles expand

3. Gross productivity changes (total photosynthesis)• Pioneer = Low density of producers at first• Middle & climax = high lots of producers and

consumers

4. Net Productivity (G – R = N)• Pioneer = little respiration so Net is large system is

growing, biomass accumulating• Middle & climax = respiration increases dramatically

N approaches zero (P:R = 1)

5. Energy flow• # of trophic levels increases over time• Energy lost as heat increases with more transfers

Climax community• Characterized by K-selected species• Determined by

– climate in the area – temperature, weather patterns– Edaphic factors – saturated wet, mesic, arid

• Climax community structure is in stable equilibrium for each area

• Humans & other factors may maintain an equilibrium below climax– E.g. current warming trends make climax rainforest

communities w/ softer wood, faster growing species

Communities

Definitions1. Population a group of individuals of a certain species in

a given area at a given time: blue crabs in the Halifax river2. Community interacting groups of populations in an

area: the scrub community on campus3. Species a group of individuals who can interbreed to

produce fertile, viable offspring: FL panthers4. Niche The role of an organism in its environment

(multidimensional): nocturnal predator of small mammals in the forest

5. Habitat Where an organism typically lives: mangrove swamps

Intraspecific Competition

• Competition between members of the same species for a common resource

• Resource: food, space, mates, etc.• Territoriality

– Organisms patrol or mark an area– Defend it against others– Good territories have

• Abundant food, good nesting sites, low predator pop.

– Disadvantage = Energy, Reduce gene pool

Interspecific Competition

• 2 or more different species involved• Competing for food, space, sunlight, water, space,

nesting sites or other limited resource• If resources abundant, they can be shared but in

nature they are always limited• If fundamental niches overlap competition• One of the species must…

1. Migrate if possible2. Shift feeding habits or behavior = Evolve3. Suffer a sharp population decline4. Become extinct

Connell’s Barnacles

Predation

• Members of one species feed directly on all or part of a living organism of a different species

• Individuals predator benefits, prey harmed

• Population prey benefits: take out the weak, greater resource access, improved gene pool

• Predator plays important ecological role

Parasitism

• One species feeds on part of another organism (the host) without killing it

• Specialized form of predation• Parasite Characteristics

1. Usually smaller than the host2. Closely associated with host3. Draws nourishment from & slowly weakens host4. Rarely kills the host

• Examples = Tapeworms, ticks, fleas, fungi

Malaria

According to the World Health Organization there are 300 to 500 million clinical cases of malaria each year resulting in 1.5 to 2.7 million deaths

The disease kills more than one million children - 2,800 per day - each year in Africa alone. In regions of intense transmission, 40% of toddlers may die of acute malaria.

In the early 1960s, only 10% the world's population was at risk of contracting malaria. This rose to 40% as mosquitoes developed resistance to pesticides and malaria parasites developed resistance to treatment drugs. Malaria is now spreading to areas previously free of the disease.

Mutualism

• Symbiotic relationship where both species benefit

• Pollination, Nutrition, Protection are main benefits

• Not really cooperation, both benefit by exploiting the other

Oxpeckers and black rhinoceros

Clown fish and sea anemone

Mutualism II

Examples1. Lichens – fungi & algae living together

food for one, structure for the other2. Plants and Rhizobium bacteria one gets

sugars the other gets nitrogen3. Oxpeckers and Rhinos food for one, less

parasites for the other4. Protists and termites break down wood

for one, nutrients for the other

Commensalism• One species benefits the

other is neither harmed nor helped

– Examples1. Herbs growing in the shade

of trees2. Birds building nests in trees3. Epiphytes = “Air plants”

which attach themselves to the trunk or branches of trees-they have a solid base to grow

on and better access to sunlight & rain

Ecosystems

Ecosystem Components

2 parts

– Abiotic – nonliving components (water, air, nutrients, soils solar

energy (insolation))

– Biotic – living components (plants, animals, microorganisms)Biota

Trophic Level

• The position that an organism occupies in a food chain, or a group of organisms in a community that occupy the same position in food chains.

Identify and explain trophic level Terminology and Roles of Biota

• Producers (Autotrophs) – Through photosynthesis convert radiant to chemical energy (energy transformation)

• Consumers (Heterotrophs) – Must consume other organisms to meet their energy needs– Herbivores, Carnivores, Omnivores, Scavengers,

Detritivores• Decomposers – Break down organisms into

simple organic molecules (recycling materials)

Local examples

Trophic Level Estuary system Everglades habitat

Producer

Primary Consumer

Seconday Consumer

Tertiary Consumer

Quarternary Consumer

6th trophic level

Local examples

Trophic Level Estuary system Everglades habitat

Producer Turtle grass Phytoplankton

Primary Consumer Grass shrimp Zooplankton

Seconday Consumer Pin fish Blue gill

Tertiary Consumer Spotted Sea trout Bass

Quarternary Consumer Osprey Racoon

6th trophic level Aligator

Figure 53.11 An antarctic marine food web: Identify the trophic levels

Pyramids

• Graphic models of quantitative differences between trophic levels

• By second law of thermodynamics energy decreases along food webs

• Pyramids are thus narrower as one ascends– Pyramids of numbers may be different large

individuals at low trophic levels – large forests– Pyramids of biomass may skew if larger organisms are

at high trophic levels biomass present at point in time – open ocean

Losses in the pyramid

• Energy is lost between each trophic level, so less remains for the next level– Respiration, Homeostasis, Movement, Heat

• Mass is also lost at each level– Waste, shedding, …

Pyramid types / characteristicsBiomass Pyramid Numbers

pyramidEnergy pyramids

It shows Storages Storages Flows

In g / m2 individuals / m2 J / m2 yr or g / m2 yr

It’s always pyramid shaped for a

Grassland Grassland There is never a case where it isn’t

It is not pyramid shaped for a(n)

Antarctic open ocean habitat

Forest (especially temperate deciduous)

It is always pyramid shaped

How does the first law of thermodynamics effect these?

How does the second law of thermodynamics effect these?

How does pyramid structure effect ecosystem function?

1. Limited length of food chains• Rarely more than 4 or 5 trophic levels• Not enough energy left after 4-5 transfers to

support organisms feeding high up• Possible exception marine/aquatic systems b/c

first few levels small and little structure2. Vulnerability of top carnivores

• Effected by changes at all lower levels• Small numbers to begin with• Effected by pollutants & toxins passed through

system

3. Biomagnification

1. Mostly Heavy metals & Pesticides• Insoluble in water, soluble in fats, • Resistant to biological and chemical degradation, not

biodegradable2. Accumulate in fatty tissues of organisms3. Amplify in food chains and webs4. Sublethal effects in reproductive & immune

systems5. Long term health effects in humans include tumors,

organ damage, …

Biomes

What is a biome?• World climate is variable

– Differences in temperature and precipitation– Different climates Different communities

• Biomes = Regions of the earth characterized by specific climates and community types

• Remember they cross national boundaries• Real biomes do not have sharply defined

boundaries. Ecotones = Transitional zones• Biomes not uniform, instead a mosiac of patches

– Vary in microclimate, soil types, disturbances

Dry woodlands and shrublands (chaparral)

Temperate grassland

Temperate deciduous forest

Boreal forest (taiga), evergreen coniferousforest (e.g., montane coniferous forest)

Arctic tundra (polar grasslands)

Tropical savanna,thorn forest

Tropical scrub forest

Tropical deciduous forest

Tropical rain forest,tropical evergreen forest

Desert

Ice

Mountains(complex zonation)

Semidesert,arid grassland

Tropic ofCapricorn

Equator

Tropic ofCancer

MountainIce and snow

Altitude

Tundra (herbs,lichens, mosses)

ConiferousForest

Tropical Forest

DeciduousForest

Tropical Forest

DeciduousForest

ConiferousForest

Tundra (herbs,lichens, mosses)

Polar iceand snow

Latitude

Main Biome Effects

Climate and vegetation vary in a predictable fashion with changes in Altitude and Latitude

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Tropicalrain forest

Coniferousforest

Deciduousforest

Thornforest

Tall-grassprairie

Short-grassprairie

Desertscrub

Thornscrub

Comparison of types, sizes and stratification of species in different terrestrial biomes (structure)

Tundra1. Climate

• Precipitation < 15 cm / yr – mostly snow & summer rain Arid• Bitter cold -57 – 50 °C - permafrost• low insolation gives short growing season

2. Distribution• 60 – 75 °N latitude – northern North America, Asia,

Greenland• About 20% of the earth’s surface

3. Structure• Simple – low spongy mat of vegetation, lichens, mosses• Even trees are less than knee high

4. Relative Productivity• Low – limited by temperature and insolation

Temperate Grasslands1. Climate

• Precipitation 25-45 cm / yr – enough to grow grass, erratic Semiarid• fire, drought, animals prevent tree growth• May be Tropical, Temperate• Moderate insolation

2. Distribution• 9% of earth surface Temperate Latitudes – Major onesNA tall grass

prairie, steppes, pampas, veldt• Grasslands overall up to 40% of earth’s surface

3. Structure• Simple – grasses and herbaceous plants

4. Relative Productivity• Medium to high – high turnover of grasses, rich soils

Deserts1. Climate

• Precipitation < 25 cm / yr – scattered unevenly through year Arid

• May be Tropical, Temperate and Cold types – always extremes• High to moderate insolation

2. Distribution• 30% of earth surface between 30 degrees north and south of

the equator – Major ones Saraha (Africa), Gobi (Asia), Mojave (N. america)

3. Structure• Simple – very little vegetation • Most complex is temperate desert which has largest cacti

4. Relative Productivity• Low – limited by water availability

Tropical Rainforest1. Climate

• Precipitation over 150 cm / yr – Wet – still rainy and dry seasons• Warm humid year round climate 80 °F • high insolation gives long growing season

2. Distribution• 23.5 °N to 23.5 °S latitude – Tropic of Capricorn to Cancer • About 2% of the earth’s surface• Three chunks – S. & C. America, C. Africa, SE Asia

3. Structure• Complex – stratified layers • High diversity - 50-80% of terrestrial species

4. Relative Productivity• Highest in terrestrial system – unlimited by temperature and insolation

Other habitats

Aquatic Life Zones

• Aquatic Biomes = Aquatic Life Zones• Salinity is a distinguishing factor

– Marine (Saltwater)• Estuaries, Coastlines, Coral reefs, Coastal

marshes, Mangroves swamps, Oceans– Freshwater

• Lakes & ponds, Streams & rivers, Inland wetlands

Mangroves

Coral reefs

Rivers

Lakes

Major Organisms

1. Phytoplankton: Free floating microscopic producers – algae & cyanobacteria

2. Zooplankton: Animal plankton – herbivores & carnivores usually invertebrates

3. Nekton: Strong swimming consumers4. Benthos: Bottom dwellers – may be sessile,

filter feeders, infauna, grazers5. Decomposers: mostly bacteria – break down

organic material

Characteristics of Aquatic Systems

• Less pronounced physical boundaries than terrestrial systems

• More complex & longer food webs and chains than terrestrial systems

• More difficult to monitor and study because of size and accessibility

Advantages Disadvantages

Physical support from water buoyancy

Fairly constant temperature

Nourishment from dissolved nutrients

Water availability

Easy dispersalof organisms, larvae, and eggs

Less exposure to harmful UVradiation

Dilution anddispersion ofpollutants

Can tolerate a narrow range of temperatures

Exposure to dissolved pollutants

Fluctuating population size for many species

Dispersion separates many aquatic offspring from parents

Fresh water

Sunlight

Paintedturtle

Greenfrog

Pondsnail

Blue-wingedteal

Muskrat

Plankton

Northernpike

BloodwormsYellowperch

Divingbeetle

Littoral zone

Limnetic zone

Profundal zone

Benthic zone

Sunlight

Little shore vegetation

Limnetic zone

Profundalzone

Oligotrophic lake

Low concentration of nutrients and plankton

Sparse fish population

Narrow littoral zone

Sleepily sloping shorelines

Sand, gravel, rock bottom

Sunlight

Much shore vegetation

Limnetic zone

Profundalzone

Eutrophic lake

High concentration of nutrients and plankton

Dense fish population

Widelittoral zone

Gentlysloping shorelines

Silt, sand, clay bottom

Epilimnion

Hypolimnion

ThermoclineSummer Fall overturn

22˚20˚

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4˚CWinter Spring overturn

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Dissolved O2 concentration High Medium Low

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Rain and snow

Water

Sediment

Lake Glacier Rapids

WaterfallTributary

Flood plain

Oxbow lake

Salt marsh

Delta Ocean

Depositedsediment

Source Zone

Transition Zone

Floodplain Zone

Capybara

Water lily

Cayman alligator

Plant planktonTerecay turtle

Animal plankton

Leporinus fish

Neon tetra

Arapaima

Piranha

Amazonian dolphin

Producerto primaryconsumer

Producerto secondaryconsumer

Secondary tohigher-levelconsumer

All producers andconsumers todecomposers

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Salt Water

Ocean hemisphere Land-ocean hemisphere

High tideLow tide

Coastal Zone

EstuarineZone

Continentalshelf

Open SeaSea level

Sun

Euphotic Zone

Bathyal Zone

Abyssal Zone

Depth inmeters

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© 2004 Brooks/Cole – Thomson Learning

Herring gulls

Snowyegret

Peregrine falcon

Cordgrass

Short-billeddowitcher

Marshperiwinkle

BacteriaClamworm

Soft-shelledclam

Zooplankton andsmall crustaceans

Phytoplankton

Smelt

Producerto primaryconsumer

Primaryto secondaryconsumer

Secondary to higher-levelconsumer

All producers and consumers todecomposers

Rocky Shore Beach Sea star Hermit crab Shore crab

NudibranchMonterey flatworm

Kelp Sea lettuce

Barnacles

Sea urchin Anemone

Low tide

Mussel

Periwinkle

High tide

Sculpin

Barrier beach

Silversides

Blue crab

Low tide

Dwarfolive

Clam

Beach flea

Tiger beetle

High tide

GhostshrimpMole

shrimp

Sandpiper

Peanut worm

White sandmacoma

Sand dollar Moon snail

Gray reef shark

Green seaturtle

Sea nettle

Fairy basslet

Bluetangs

Brittle star Banded coralshrimp

Sergeant majorParrot fish

Hard coralsAlgae

Phytoplankton

Symbioticalgae

Zooplankton

Sponges

Bacteria

Morayeel

Blackcap basslet

Coney

Producerto primaryconsumer

Primaryto secondaryconsumer

Secondary to higher-levelconsumer

All consumers and producers todecomposers

Ocean warming

Soil erosion

Algae growth from fertilizer runoff

Mangrove destruction

Coral reef bleaching

Rising sea levels

Increased UV exposure from ozone depletion

Using cyanide and dynamite to harvest coral reef fish

Coral removal for building material, aquariums, and jewelry

Damage from anchors, ships, and tourist divers

Terms• Biodiversity: Genetic, Species, Ecological, Functional (processes).• Genetic Diversity: change in size, age distribution, density, genetic

composition• Habitat: one species. Community: several species. Ecosystem:

several species and abiotic environment.• Biomes: distinct climates—terrestrial (forests, deserts, grasslands), aquatic

(Freshwater, Ocean or Marine).• Ecotone: non-distinct boundary between ecosystems.• Law of Tolerance: population distribution determined by physical/chemical

factors.• Limiting Factor Principal: too much/little abiotic factor (temp, light, DO,

nutrients, salinity) can limit/prevent population growth.• Producers (Autotrophs): “self-feeders” (plants, phytoplankton use CO2,

light, nutrients, etc.).• Anaerobic Respiration (Fermentation): no oxygen used (CH4, C2H5OH,

CH3COOH, H2S products).• Consumers (Heterotrophs): “other feeders” (herbivores, carnivores,

omnivores, scavengers, detritivores (long-horn beetle), detritus feeders, decomposers

Terms

• Aerobic Respiration: oxygen used (C6H12O6 + 6O2 6CO2 + 6H2O + energy)• Food Web or Chain: represent trophic levels of interacting species (primary

consumers eaten by secondary and so forth.• Energy Pyramid: like food web but shows energy flow between tropic

levels.• Ecological Efficiency: % usable energy transferred in biomass between

trophic levels.• (SunProducersHerbivoresCarnivoresDecomposersDecomposers

/detritivores).• Biomass Abandoned Field / Grassland: greatest to least (producers,

primary, secondary, tertiary consumers).• Biomass Ocean / Forest: greatest to least (primary, secondary consumers,

producers, tertiary consumers).• Absolute Humidity: g. H2O / kg. Air Relative Humidity: [g. H2O

(temp.) / g H2O max (temp.)] x 100%• Condensation Nuclei: ash, dust, smoke, sea salts, fossil fuel particulates.