EcologyUnit 10

Ecology = The scientific study of interactions among organisms and between organisms and their environment

Biosphere = Area of the earth where life exists; extends from the ocean’s depths to a few kilometers above land

Biome = Extensive areas of similar climate and vegetation; ecologists recognize at least ten different biomes

Words to know…

Biotic factors = living factors, such as plants and animals

Abiotic factors = non-living factors, such as climate, water, sun, rock, etc.

Words to know…

Terrestrial Biomes

Abiotic factors: hot and wet year-round; thin, nutrient poor soils

Dominant plants: broad-leaved evergreen trees; ferns; large woody vines and climbing plants

Geographic distribution: parts of South and Central America, Southeast Asia, parts of Africa, southern India, and northeastern Australia

Tropical Rain Forest

Abiotic factors: generally warm year-round; alternating wet and dry seasons; rich soils subject to erosion

Dominant plants: tall, deciduous trees that form a dense canopy during the wet season

Geographic distribution: parts of Africa, South and Central America, Mexico, India, Australia, and tropical islands

Tropical Dry Forest

Abiotic factors: warm temperatures; seasonal rainfall; compact soil; frequent fires set by lightning

Dominant plants: tall, perennial grasses; sometimes drought-tolerant and fire-resistant trees or shrubs

Geographical distribution: large parts of eastern Africa, southern Brazil, northern Australia

Tropical Savanna

Abiotic factors: low precipitation; variable temperatures; soils rich in minerals but poor in organic material

Dominant plants: cacti and other succulents; plants with short growth cycles

Geographic distribution: Africa, Asia, Middle East, United States, Mexico, South America, Australia

Desert

Abiotic factors: warm to hot summers; cold winters; moderate, seasonal precipitation; fertile soils; occasional fires

Dominant plants: lush, perennial grasses and herbs; most are resistant to drought, fire, and cold

Geographic distribution: central Asia, North America, Australia, central Europe, and upland plateaus of South America

Temperate Grassland

Abiotic factors: hot, dry summers; cool, moist winters; thin, nutrient-poor soils; periodic fires

Dominant plants: woody evergreen shrubs with small, leathery leaves; fragrant, oily herbs that grow during winter and die in summer

Geographic distributions: western coasts of North and South America, areas around the Mediterranean Sea, South Africa, and Australia

Temperate Woodland and Shrubland (Chaparral)

Abiotic factors: cold to moderate winters; warm summers; year-round precipitation; fertile soils

Dominant plants: broadleaf deciduous trees; some conifers; flowering shrubs; herbs; a ground layer of mosses and ferns

Geographic distribution: eastern United States; southeastern Canada; most of Europe; and parts of Japan, China, and Australia

Temperate Forest

Abiotic factors: mild temperatures; abundant precipitation during fall, winter, and spring; relatively cool, dry summer; rocky, acidic soils

Dominant plants: Douglas fir, Sitka spruce, western hemlock, redwood

Geographic distribution: Pacific coast of northwestern United States and Canada, from northern California to Alaska

Northwestern Coniferous Forest

Abiotic factors: long, cold winters; short, mild summers; moderate precipitation; high humidity; acidic, nutrient-poor soils

Dominant plants: needleleaf coniferous trees such as spruce and fir; some broadleaf deciduous trees; small, berry-bearing shrubs

Geographic distribution: North America, Asia, and northern Europe

Boreal Forest (Taiga)

Abiotic factors: strong winds; low precipitation; short and soggy summers; long, cold, and dark winters; poorly developed soils; permafrost

Dominant plants: ground-hugging plants such as mosses, lichens, sedges, and short grasses

Geographic distribution: northern North America, Asia, and Europe

Tundra

Mountain Ranges – found on all continents, abiotic and biotic conditions vary with elevation

Polar Ice Caps – cold year-round, very few plants and algae◦ North polar region – dominant animals are polar

bears, seals, insects, and mites◦ South polar region – dominant animals are

penguins and marine mammals

Other land areas

Aquatic Biomes

Nearly ¾ of Earth’s surface is covered with water

Determined by depth, flow, temperature, and chemistry of the over-lying water

Aquatic Ecosystems

Rivers, streams, creeks, and brooks Animals have adaptations, such as hooks,

suckers, streamlined bodies, etc. Often come from underground water source Turbulent water = plenty of dissolved

oxygen

Flowing freshwater

Lakes and ponds Water flows in and out, usually circulates

helps distribute heat and oxygen Relatively still water allows organisms like

plankton to survive

Standing freshwater

Wetland – ecosystem in which water either covers the soil or is present at or near the surface of the soil for at least part of the year

Bogs, marshes swamps Support very specific plants and animals

Freshwater wetlands

Wetlands formed where river meets sea Brackish = fresh water + salt water Most organic material enters as detritus –

made up of tiny pieces of organic material, consumed by clams, worms, sponges, etc.

Salt marshes = temperate zone estuaries Mangrove swamps = tropical coastal

regions

Estuaries

Photic zone – relatively thin (200 meters) upper layer where light can penetrate photosynthesis can occur

Aphotic zone – permanently dark, chemosynthetic producers only

Marine biologists divide ocean by photic and aphotic zones as well as depth and distance from shore

Marine Ecosystems

Submerged in sea water once or twice a day, otherwise exposed to air and sunlight

Zonation – prominent horizontal banding of organisms that live in a particular habitat

Intertidal Zone

Extends from low-tide mark to outer edge of continental shelf

Shallow enough to mostly fall in photic zone allows for plankton, kelp, etc. to survive

Coastal Ocean

Warm, shallow water of tropical coastal oceans

Named for coral animals whose hard, calcium carbonate skeletons make up their primary structure

Need warm water, bright sun, and salt, grow with help of algae

Coral Reefs

Begins at edge of continental shelf and extends outward

90% of the surface area of the world’s ocean

Organisms are exposed to high pressure, frigid temperatures, and total darkness

Most productivity occurs in photic zone

Open ocean

Ocean floor Creatures that live here (such as sea stars,

anemones, marine worms, etc.) are called benthos

Often depend on food from organisms that grow in the photic zone that drifts down

Benthic zone

Ecosystems, Populations, and

Communities

An ecosystem is a physically distinct, self supporting unit of interacting organisms and their environment

Includes biotic and abiotic factors Four important processes:

◦ Production of energy (usually from sunlight)◦ Energy transfer◦ Decomposition◦ Reuse of nutrients

Ecosystems

Community = all of the ecosystem’s interacting biotic factors

May be broken down into smaller units called populations

Population = a group of individuals that belong to the same species, occupy the same area, and share common resources

Each population has a specific niche, which means total way of life habitat, place in food web, competition, interrelationships, and resource needs

A community may have 1000’s of populations (rain forest) or relatively few (tundra)

Communities and Populations

Organisms in a community survive by either producing or consuming food

Trophic level = level of feeding in a community

Producers produce food for themselves Consumers must take in food from other

sources

How does energy move through an ecosystem?

Primary consumers eat producers “herbivores” (eat only plants)

Secondary and Tertiary consumers can be carnivores (eat only meat) or omnivores (eat plants and meat)

Decomposers break down wastes and dead organisms, return nutrients to soil

How does energy move through an ecosystem?

Made up of overlapping food chains Shows feeding connections Arrows illustrate energy transfer flow in

direction of energy

Food webs

Producers have most available energy (from sun) Energy is lost as it moves up through the food web

“10% rule” = only 10% of the energy is transferred to the next highest trophic level

The “lost” energy is used to catch, eat, and digest food. Decomposers return nutrients and energy to soil.

Energy efficiency

Population growth – populations will grow until they reach their carrying capacity exponential growth – “J curve”

Limiting factors, such as availability of food, space, mates, etc. establish the carrying capacity (the # of individuals an environment can support) – “S curve”

How do populations change over time?

Succession = the idea that communities will replace other communities in a predictable, orderly way because every community alters the physical factors of the environment

Two kinds:◦ Primary – occurs in areas that have not

supported communities before◦ Secondary – occurs in areas that have supported

communities before

Ecological Succession

Pioneer species – first organisms to inhabit an area, must be able to survive harsh conditions

Intermediate communities – multiple communities that each change the environment and “pave the way” for other communities

Climax community – final stage in succession, most stable community for that biome

Ecological Succession

Community interactions

Competition = a struggle for resources among organisms

Predation = organisms consume other organisms◦ Predators = organisms doing the eating◦ Prey = organisms getting eaten

Symbiosis = two organisms of different species living together in a close, permanent relationship

How do living things interact in a community?

Mutualism – the two organisms benefit each other

Commensalism – one organism benefits and the other is neither benefitted nor harmed

Parasitism – one organism benefits and the other is harmed

Symbiosis

Biogeochemical Cycles

Pathways through which a substance is recycled.

Water cycle Carbon cycle Nitrogen cycle

Biogeochemical Cycles

Enters ecosystem through precipitation, could be absorbed into soil or run-off into surface water

Returns to atmosphere through evaporation or transpiration (loss of water by plants)

Water Cycle

Powered by two main processes:◦ Photosynthesis – plants and

algae capture CO2 from air and change it to sugar which contains carbon

◦ Respiration – all living things break down sugars for energy, which returns CO2 to atmosphere

Other factors:◦ Decomposition returns carbon

to soil and atmosphere◦ Humans burn fossil fuels which

adds CO2 to atmosphere

Carbon Cycle

Nitrogen is essential for living organisms so that they can build proteins

Nitrogen is plentiful in the atmosphere, but not usable in this form

Nitrogen fixation = bacteria living in the root nodules of bean plants convert nitrogen from the air into a more usable form

Nitrogen fixation is the first of many steps that involves bacteria and changing the form of nitrogen

Nitrogen Cycle

Studying Ecology

Global positioning system – satellite based navigation system that allows the exact determination of a location. This is used for GIS (geographic information systems) which can:◦ Store, manage and integrate data relating to

points (individual trees), lines (rivers, roads), and boundaries

◦ Search for areas with a particular factor (ex. species)

◦ Perform geographical analysis◦ Display data in maps

What technology helps scientists study the complex systems in ecology?

Biological Sampling – techniques that allow scientists to quantitatively evaluate an area in terms of its biotic factors◦ Mark/recapture method – allows scientists to

estimate a population number in area, scientist captures a segment of population, marks them, releases them, and then recaptures another segment of the population, counting the number of “marked” individuals recaptured, using these numbers to estimate the total population size.

What technology helps scientists study the complex systems in ecology?

Quadrant analysis – scientists use a quadrant to select an area of an ecosystem reduces space a scientist must analyze, ensures the size of area remains the same if the scientist chooses to analyze several areas or the same area over a period of time

Water/soil analysis – using chemical tests or sampling techniques to determine the chemical or physical characteristics of water or soil

What technology helps scientists study the complex systems in ecology?

Human Impact

Human population has been growing exponentially since the industrial age better medicine, better living conditions, more food = more people

Current Population

Human Population

Separated down the middle: right side = female, left side = male

Organized vertically by age Organized horizontally by percent of total

population

Human Population - Graph

Developed vs. Developing Countries Developed

◦ 20% of population◦ 85% of wealth◦ Average life span – 78

years◦ Infant deaths per 1000

births – 9◦ Population under 15 –

19%

Developing◦ 80% of population◦ 15% of wealth◦ Average life span – 63

years◦ Infant deaths per 1000

births – 64◦ Population under 15 –

35%

Pollution = process that releases harmful substances into the air, land, or water

Acid rain = rain that contains nitric and sulfuric acids

Human Activity

Pesticides = Chemicals used to kill insects by farmers; some insects survive and develop a resistance

Deforestation = Cutting down plants for fuel, agriculture, etc. This results in less photosynthesis and more CO2 in the atmosphere

Human Activity

Greenhouse gases = Trap UV radiation from the sun, raises the temperature of the Earth (CO2)

Ozone depletion = Ozone layer reflects UV radiation back to the sun; less ozone = more gets through to heat the Earth

Human Activity

CFCs= Chlorofluorocarbon; an organic compound usually found in refridgerants, aerosols, and solvents, destroys ozone layer

Fossil fuels = Hydrocarbons (hydrogen and carbon) formed from organisms that died millions of years ago, release CO2 when burned; ex. coal and oil

Human Activity

Keystone species = used as a standard to evaluate the health of an ecosystem; more sensitive to biological changes than other species

Native species = those that originate or occur naturally in an area or environment

Invasive species = those that are artificially introduced to an area or environment; can be very destructive

Human Activity

Bioaccumulation = accumulation of a substance, such as a toxic chemical in the tissues of a living organism

Biomagnification = the increasing concentration of these toxins at successively higher trophic levels in a food chain

Human Activity

Animal Behavior

The way an organism reacts to changes in its internal condition or external environment.

Stimulus = any kind of signal that carries information and can be detected

Response = a single, specific reaction to a stimulus

What is behavior?

Innate behavior = instinct, inborn behavior; fully functional the first time they are performed, even if the animal may have had no previous experience with the stimuli to which it responds

Learned behavior – learned, developed responses, more common in animals with more complex nervous systems, four major types are habituation, classical conditioning, operant conditioning, and insight learning

Different types of behavior

Habituation – process by which an animal decreases or stops its response to a repetitive stimulus that neither rewards nor harms the animal

Example: A puppy is frightened by the vacuum cleaner, so he barks and growls at it. After a while, he realizes it is not hurting him, so he stops barking and growling.

https://www.youtube.com/watch?v=Kfu0FAAu-10

Classical conditioning – animal makes a mental connection between a stimulus and some kind of reward or punishment.

Example: Ivan Pavlov noticed that dogs salivate when they are about to eat. He rang a bell every time he fed his dog, and eventually, just ringing the bell would cause the dog to start drooling. The dog had associated the bell with being fed.

https://www.youtube.com/watch?v=nE8pFWP5QDM

Operant conditioning – when an animal learns to behave a certain way through repeated practice (trial and error) in order to receive a reward or avoid a punishment motivation

Example: B. F. Skinner invented the “Skinner box,” which contains a colored button that releases food if the animal inside presses it. Eventually, the animal will learn to press the button whenever it wants food.

https://www.youtube.com/watch?v=Mt4N9GSBoMI

Insight learning – the animal applies something it has already learned to a new situation without “trial and error” reasoning

Example: A chimpanzee piles boxes on top of each other in order to reach bananas that are out of his reach.

https://www.youtube.com/watch?v=fPz6uvIbWZE

Imprinting – young animals recognize and follow the first moving object they see. They have an innate urge to follow the first thing they see, but they do not know what it will look like.

https://www.youtube.com/watch?v=4cSJHtatBGQ

Combining innate and learned behavior

Migration – periodic movement from one place to another and then back again, usually influenced by changing seasons

Circadian rhythms – daily patterns of behavior, such as sleeping at night and being active during the day

Estivation – animals reduce their metabolism during the summer or periods of extreme heat

Hibernation- animals reduce their metabolism during the winter or periods of extreme cold

Behavioral cycles

An animal must locate and mate with another member of its species in order to pass on its genes.

Courtship rituals – series of behaviors performed the same way by all members of a population, continues until mating occurs.

https://www.youtube.com/watch?v=XgnOQqLhrlw

Courtship

Membership in a society can provide protection from predators

Members of a society are closely related to one another helping a relative survive increases the chance that the genes an individual shares with that relative will be passed along to offspring

Social Behavior

Mimicry – an animal imitates a more dangerous animal to discourage predators

Crypsis – an animal can blend into the background or stand very still in the presence of a predator to avoid detection

Vigilance – an animal actively looks, listens, sniffs, etc. for predators

https://www.youtube.com/watch?v=zsG4CdhJvjg

Defensive Behavior

Territory – specific area occupied and protected by an animal or group of animals, usually contains resources like food, water, mates, etc.

Aggression – threatening behavior that one animal uses to gain control over another https://www.youtube.com/watch?v=RVJduMnXAns

Competition

The passing of information from one individual to another

Visual signals – using movement, color, shape, etc. to communicate

Chemical signals – using scents, pheromones, etc. to communicate

Sound signals – using specific sounds to communicate

Language – combination of sounds, symbols, and gestures according to sets of rules about word order and meaning, only used by humans or animals trained by humans

Communication

Thermotaxis– attraction to heat, move towards it

Chemotaxis– attraction to chemical, usually detected through taste or smell, move towards it

Phototaxis – attraction to light, move towards it

Movement