unit 10. ecology = the scientific study of interactions among organisms and between organisms and...
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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
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