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Transcript of Ecosystem
Study of relationships of organisms with one another and their environment:
a SINGLE member of a species.
organisms capable of interbreeding and producing fertile offspring.
organisms of the SAME species interacting within a community.
composed of DIFFERENT species interacting with one another.
a biological community and it’s physical environment (biotic & abiotic)
all ecosystems on the entire Earth
Created by D. Chigounis, 2013
Based on Barron's AP ES 5th Edition & Princeton Review AP ES 2014
Types of Dispersion
Organisms can be dispersed THREE ways:
: some areas are dense with organisms while others contain few.
Occurs when resources are patchy.
Most common form of dispersion.
Examples: Elephants clumped together near watering hole.
Example: Lions clumped together in prides.
Example: Red-headed Woodpecker have specific requirements.
: random spacing patterns / little interaction between members of the population.
usually occurs in habitats where env. conditions and resources are consistent.
characterized by lack of strong social interactions.
Example: Dandelion seeds being dispersed by wind
: Uniform spacing between individuals.
Need to maximize space between individuals arises from competition, territory, etc.
Example: Penguins defending nest sites.
Example: Fiddler crabs defending their burrows
Types of Dispersion
: organism’s role within the community.
organisms adaptive traits
biotic & abiotic interactions
Generalists vs. Specialists
Generalist species (K)
live in broad niches & are capable of withstanding wide range of environmental conditions.
Examples: cockroaches, mice, humans
Specialist species (r)
live in narrow niches and are sensitive to environmental changes – therefore, more prone to extinction.
Example: giant panda, Senegal Chameleon
When environmental conditions are stable, specialists have advantage since they’re well adapted to specific niche (competitive exclusion principle)
When habitats change, generalists fare better since more adaptable to change.
Law of Tolerance and Limiting Factors
Law of Tolerance
: the existence, abundance and distribution of species depends on the tolerance level to biotic and abiotic factors. Ex) climate, topography, biological factors
Law of Minimum:
organisms will survive until they run out of resources (food) is exhausted.
: any factor (biotic or abiotic) that limits or prevents the growth of a population. Ex) soil nutrients, available water or light, temperature, pH, DO, salinity, predation, disease, shortage of mates, etc
Resources are limited
Some species evolved to share a resource
: two species use same resource at DIFFERENT TIMES.
e.g. monkeys feed on fruit during day while fruit bats feed at night.
: competing species use same resource by occupying DIFFERENT AREAS of habitat.
e.g. flounders feed along benthos while pelagic fishes feed in open waters.
: species use same resource but have evolved DIFFERENT STRUCTURES to use resource.
e.g. two different species of bees evolved different proboscis lengths to access different types of flower nectar.
Interactions Among Species
Interactions among species can benefit, harm, or not affect one of the species involved.
: one species suffers and the other is not impacted: ex) bread mold, Penicillium secretes penicillin, which kills competing bacteria.
: one species benefits and the other is not impacted. ex) juvenile bar jack fishes swing along side of large barracuda to avoid medium sized predators.
BOTH species benefit.ex) flower and pollinating honey bee.
: one species benefits and the other is harmed. ex) lamprey and lake trout.
one species hunts down and feeds on another.
: a species that obtains nutrients from dead plants and animals. ex) fungi, bacteria, protoza, vultures, dung beetles
: two species compete for a resource.
two members of the SAME species compete.
: two different species compete.
a species whose presence contributes to a diversity of life and whose extinction would lead to the extinction of other forms of life.
Keystone species have disproportionate impact on how ecosystems function.
ex) sea star prey on sea urchins, mussels, etc. that have no other predators. Removal of sea star, would lead to overpopulating of prey species which decimate coral reef.
ex) sea otters prey on sea urchins. If sea otters were removed, urchins would destroy kelp forests, which support vast amounts of other species.
: a species whose presence, absence, or well-being indicates the health of its ecosystem as a whole. Provide EARLY WARNING system! (Canary in Coal Mine)
: occurs when the food web is disrupted by the removal of a top predator or producer, which then has a ripple down or up affect on the rest of the ecosystem. ex) removal of wolves from Yellowstone had subsequent influence on coyote, elk, ravens, bear, and willow. Cascading can be "bottom up" or "top down".
reduces need for support structures
high heat capacity translates into less temperature regulation expenditure for organism
allows dispersal of gametes / larvae to new areas
filters UV radiation
organisms adapted: tough shells, exoskeletons, salt removal mechanisms, low metabolic rates (due to cooler ambient temperatures)
Desert plants adaptions:
spaced apart due to limiting factors.
primarily consist of succulents (cacti) and short lived annuals (wildflowers)
small surface area
open stomata at night
waxy coating to minimize transpiration
deep roots to tap groundwater
sharp spines for protection
secrete toxins into soil to discourage competition (allelopathy)
Desert animal adaptation:
smaller surface area
secrete concentrated urine
insects & reptiles have thick shells / skin to reduce water loss
Grasses grow from the bottom (basal meristem) so they can recovery from grazing.
Deciduous trees & shrubs shed leaves during dry season to conserve water
Herbivores eat vegetation at different heights so as not to compete
Some organisms migrate to find water while others go dormant
Organisms burrow to avoid predation
Camouflage plays a big role in evading predators / ambushing prey
some organisms live in canopies where shelter and food are abundant
epiphytes (orchids and bromeliads) live on tree branches & have access to falling organic matter. Obtain moisture from air rather than soil
plants in understory have large leaves to maximize sunlight absorption.
plants and trees have shallow roots to capture nutrients in soil
Flowers have elaborate devices to attract pollinators since wind in minimal
Temperate Deciduous Forests:
broad-leaf deciduous trees lose their leaves in winter and become dormant
shift metabolism from photosynthesis in summer to utilizing glucose and amino acids in winter (also keeps trees from freezing and acts as natural antifreeze)
Evergreen Coniferous Forests:
conifers (pine, spruce, hemlock, etc. have small waxy-coated needles able to withstand cold and drought.
low surface area reduces transpiration
decomposed needles acidify soil (allelopathy)
some organisms hibernate to conserve energy during winter
(temperate shrub forest)
small, waxy-coated leaves reduce transpiration
many produce toxins that leach into soil preventing competition (allelopathy)
Vegetation becomes dormant during dry season
dead leaves remain on shrubs during dry season
thorns are common trait
vegetation adapted to fires and high oil content found in brush
fires reduce competition and allow for germination
rodents are common and store seeds underground
low amounts of available water
plants grow during summer months
waxy-coating on leaves of plants
roots, stems, bulbs, and tubers
lichens dehydrate during winter to avoid frost damage
animals contain excess fat & biological antifreeze
compact bodies conserve heat
thick skin, fur, and waterproof feathers
animals migrate or move underground during coldest months
: refers to boundary or edge between two habitats.
ex) forest edges are created when trees are harvested or clear cut. Trees provide shade and shelter but their removal allows sunlight to penetrate and provide access to grasses, saplings, and shrubs.
Major Marine Biomes
The Ocean – Photic and Aphotic Zone
: receives light (aka euphotic)
: receives little (not enough for photosynthesis) to no light (consists of the bathyal & abyssal zones)
Shallow to Deep:
The ocean layer that receives enough sunlight for photosynthesis to occur.
It varies with season and latitude, from 0 to 1,200 ft. (0–360 m).
This zone includes pelagic fishes, marine mammals, phytoplankton & zooplankton.
Bathyal (Twilight) Zone
The ocean layer that receives minimal light (only blue spectrum).
No photosynthesis takes place here.
Most fish are blue and red to avoid detection. (Blue spectrum light extends to greater depths than other colors)
The abyssal zone or the “abyss”, ranges from 4,000 meters (13,124 feet) to 6,000 meters (19,686 feet).
The name comes from the Greek word meaning “no bottom”.
The water temperature is near freezing, and there is no light in this zone.
Very few creatures can be found in these freezing, dark, and bone crushing (high pressure) depths.
Most inhabitants are invertebrates - animals without a backbone, such as basket stars and tiny squids.
Those organisms that do exist in this zone rely on bioluminescence. (Video)
Bays or semi-enclosed bodies of brackish water that form where rivers enter the ocean.
Contain a high amount of plant life.
Usually carry rich sediments (nutrients ) from the river.
Wetlands perform several important environmental functions.
Act like filters or sponges that absorb and remove
pollutants from the water.
Control flooding by absorbing extra water when rivers overflow.
Provide a home for large amount of biodiversity.
Coral Reefs - Accumulated skeletons of coral polyps.
Coral has a mutualistic relationship with algae, so it needs sunlight and warm water to survive.
ound along the shore, in shallow waters, close to the equator.
Among most endangered communities.
Humans hunting tropical fish
Occur between 15' - 25' north and south latitude.
Generally occur within interior of continents.
Rainfall less than 20'' per year.
Air currents descending (rain requires ascending air - orographic lifting).
Soils abundant in nutrients but lack organic matter (little humus).
Characterized by rainfall, NOT
Freshwater Wetlands Include:
riparian areas (areas near rivers / streams)
saturated ground with freestanding water (may be seasonal)
speciose: insects, amphibians, reptiles
critical for freshwater supplies
water input: runoff, groundwater flow, streams
Lake: large body of water surrounded by land.
Majority are freshwater
Usually occur at higher latitudes
Classified on basis of nutrient richness:
clear, low nutrients, little biomass
: average amt. of nutrients, healthy.
: rich in nutrients, diverse populations of phytoplankton & zooplankton
: excessively enriched with nutrients, subject to large scale algal blooms
Found in areas too dry for forests & too wet for deserts
Occupy 25% of all land on Earth
Few trees & shrubs due to frequent fires and available water
Grasses and perennials dominate landscape
Roots well developed
Soils rich in organic matter
Upper soil horizons are alkaline, dark, & rich in humus.
Utilized for agriculture
Intermediate environment between grasslands and forest
Extended dry season followed by rainy season
Consists of grasslands with stands of deciduous shrubs & trees
Plants shed leaves during dry season
Limited food during dry season overcome by migrations
Soils rich in nutrients
Large herds of grazing animals
Taiga (coniferous / boreal forests)
Located between 45' - 60' north latitude
17% of Earth's surface
Two types of taiga:
Receives more rain than tundra
Nutrient-poor soils (due to leaching from rainfall)
Acidic soil (due do decomposition of needles)
Decomposition slow due to cold temps.
Understory receives little light due to dense trees.
Low biodiversity due to harsh environment
Temperate Deciduous Forest
Forests found in milder temperatures than boreal and taiga
Experience four seasons
Rapid decomposition due to mild temps. and precipitation
Limited amount of surface litter
Exploited for agriculture, lumber, urban development
Nutrient poor soil
Tall deciduous trees
Rich, diverse understory
Low density of large mammals - shade prevents ground vegetation
Temperate Rain Forests
Rainfall exceeds 100'' per year
Low biodiversity (due to limited light)
Major source for timber
Forests dominated by massive conifers
Hot, dry summers
Mild cool & rainy winters
Subtopical high-pressure exists over area in summer & spring
Midlatitude cyclones produce rain during winter
Avg. rainfall 15-40'' per year
Characterized by dense shrub growth
Slow decomposition during dry months
Few large mammals
Subject to erosion & fires
Found along coastal regions
Tropical Rain Forests
Average temperature 80 degrees
Annual rainfall averages 75-100''
Located within Hadley cells
Very high species diversity (flora and fauna)
Low nutrient soils (most nutrients stored in vegetation)
Rapid decomposition due to temperature and moisture
Leaching is high
Subject to clear-cutting for agriculture and pastures
Lack of soil nutrients requires high fertilizer input
60' N. latitude and above
Influenced by polar cells
Alpine tundra is located in mountainous areas, above tree-line with well drained soils
Small rodents & insects dominate biome
Arctic tundra is frozen, treeless, with low precipitation and poor drainage (due to permafrost)
Growing season lasts two months
Nutrient poor soil due to limited vegetation
Permafrost: permanently frozen ground
Photosynthesis & Cellular Respiration
Ultimate source of energy is the sun
Plants use light energy to create food (glucose)
Glucose is used by all organisms to create energy (ATP)
6CO2 + 6H20 + SL -> C6H12O6 + 6O2
Process takes place in organelle (chloroplasts)
Chloroplasts contain green pigment, Chlorophyll
ATP used to create macromolecules, carry out life functions
Plants produce less carbon than they absorb (carbon sinks)
Plants & algae that produce own food (autotrophs)
Organisms that consume autotrophs are heterotrophs
Factors influencing rate of photosynthesis:
amount of light & wavelength
is OPPOSITE of photosynthesis
C6H12O6 + 6O2 -> 6CO2 + 6H2O + 36ATP (energy)
Primary Producers (autotrophs)
: are plants and algae
Autotrophs convert light energy into chemical energy via photosynthesis
Primary Consumers (heterotrophs)
: obtain energy via eating primary producers
Primary consumers have evolved defense mechanisms against predation:
speed, flight, quills, tough hides, camouflage, horns, antlers
(heterotrophs) may be
(meat eaters) or
(eat both plants and animals)
: includes herbivores (only eat plants and algae)
: consumes primary consumer
consumes secondary consumer
: derive energy from consuming nonliving organic matter (dead animals & plants)
bacteria and fungi that absorb nutrients from nonliving organic matter (plants, animals, & feces)
NPP vs. GPP
Net Primary Productivity (NPP)
is the amount of energy that plants pass on to the community of herbivores in an ecosystem. (Energy passed on AFTER cellular respiration)
NPP is calculated by taking the
Gross Primary Productivity (GPP)
, which is the TOTAL amount of sugar the plants produce via photosynthesis, and subtracting it from the amount of energy plants need for growth, maintenance, repair, and reproduction.
GPP - Respiration = NPP
NPP measured in kilocalories per square meter per year (kcal / m2 / y)
: bacteria that convert inorganic compounds into glucose. Considered to be producers but use NO light.
Primary producers within hydrothermal vent communities.
Chemotrophic bacteria play a role within the terrestrial nitrogen cycle too.
represented as series of steps
arrows depict flow of energy outward
(dry weight of organism(s))
overly simplistic; not representative of entire community's trophic progression
Ten Percent Rule
only 10% energy transferred between trophic levels
90% lost via:
primary consumers obtain more energy than secondary and so on
energy measured in kilocalories (kcal)
Aside from food, toxins can also travel through food chains
Concentration of toxins increase at each successive level
Many toxins cannot be broken down by organisms
Toxins accumulate in fatty tissue
: term used to describe toxin buildup in tissue of living organism.
term used to describe increasing concentration of these toxins as they travel
THROUGH the food chain.
More accurate method of depicting trophic activity
Unlike food chains, removal of one organism will not collapse entire community
Carrying Capacity (K):
the number of organisms the environment can support.
the potential growth of a population assuming no limiting factors existed.
: factors (drought, starvation, available mates) that restrict the biotic potential of a population
Temperate Deciduous Forest
Temperate Rain Forest
Tropical Rain Forest
: means the diversity, or variety, of plants and animals and other living things in a particular area or region.
: the number (variety) of different species represented in an ecological community.
how close in NUMBER each species in an environment are to one another. (how proportionate)
: process whereby organisms better adapted to their environment tend to survive and produce more offspring.
allows organisms to evolve
works on individual level
advantageous traits are passed on to offspring
occurs over successive generations
environmental change triggers natural selection
The selective breeding of organisms by humans for specific characteristics.
Types of Evolution
Stabilizing, Direction & Diversifying Selection
Also known as a “tree of life”.
Organisms are grouped and classified based on three characteristics:
Mating rituals, territorial, aggression, etc.
The more of these characteristics two organisms have in common, the more closely related they are according to evolution.
The gradual transition from one community to another following a disturbance
: the colonization of an area with bare ground
: those species such as lichen and mosses that do not require soil and are first to colonize an area.
: the community best able to exploit the available resources (the final community)
: occurs where a community previously existed.
Adaptive Radiation: Diversification of a species into several forms that are each adaptively specialized to a specific environmental niche
Parallel Evolution: when similar characterisitcs arise in closely related organisms (see Cichlid pic.)
Biological Populations & Communities
population dispersal patterns
ecological niches - generalist vs. specialist
amensalism, commensalism, mutualism, parasitism
Species Diversity (adaptations)
Food Webs and Trophic Levels
stabilizing vs. directional vs. disruptive
CC = ER - BP
Directional: variation shifts in one direction
Stabilizing: variation decreases within a species
Diversifying: a species increases variation
an organism (plant, animal, fungus, or bacterium) that is not native and has negative
ecological and/or economical effects.
How Wolves Changed Rivers
Imax Tropical Rain Forest