Transcript File

Unit 2 Test Review
Biogeochemical cycles
• Biogeochemical Cycles, or Nutrient cycles, is how
elements, chemical compounds, and other forms of
matter are passed from one organism to another and
from one part of the biosphere to another.
• Types of Biogeochemical Cycles:
– Hydrologic- ex water cycle
– Atmospheric- ex carbon cycle and nitrogen cycle
– Sedimentary – ex phosphorus cycle
Evaporation and Transpiration
Condensation and Precipitation
Runoff, Seepage, and Root Uptake
• Organisms need nitrogen to build
proteins.
• Different forms of nitrogen cycle through
the biosphere.
• Nitrogen gas is the most abundant form
of nitrogen on Earth.
• It cannot be directly used by organisms.
• Nitrogen must be converted into
compounds that can enter food webs by
the process of “Nitrogen Fixation”
• Homeostasis requires a conatant energy imput
and is maintained in ecosystems by the cycling
of matter through biotic and abiotic portions
of the ecosystem
• Biogeochemical cycles demonstrate the Law of
Conservation of Matter
– a fundamental principle of classical physics that
matter cannot be created or destroyed in an
isolated system
What is Ecology??
• The study of interactions that
take place between organisms
and their environment.
• It explains how living organisms
affect each other and the world
they live in.
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Habitat & Niche
• Habitat is the
place a plant or
animal lives
• Niche is an
organism’s total
way of life
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The Nonliving Environment
• Abiotic factors- the
nonliving parts of an
organism’s environment.
• Examples include air
currents, temperature,
moisture, light, and soil.
• Abiotic factors affect an
organism’s life.
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The Living Environment
• Biotic factors- all the
living organisms that
inhabit an environment.
• All organisms depend on
others directly or
indirectly for food,
shelter, reproduction, or
protection.
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1st Level of Organization
• Organism:
An individual
living thing that is
made of cells,
uses energy,
reproduces,
responds, grows,
and develops
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2nd Level of Organization
• Population:
A group of
organisms, all
of the same
species, which
interbreed and
live in the same
place at the
same time.
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3rd Level of Organization
• Community:
All the
populations of
different
species that live
in the same
place at the
same time.
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4th Level of Organization
• Ecosystem:
Populations of plants
and animals that
interact with each
other in a given area
with the abiotic
components of that
area. (terrestrial
or aquatic)
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5th Level of Organization
• Biome:
A group of
ecosystems that
share similar
climates and
typical organisms
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6th Level of Organization
• Biosphere:
The portion
of Earth
that
supports
life.
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The Biosphere
• Life is found in air, on land,
and in fresh and salt water.
• The BIOSPHERE is the
portion of Earth that
supports living things.
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Producers
• Autotrophs
– store energy in
forms that make it
available to other
organisms
– They are known as
primary producers
• First producers
• Essential to flow of
energy
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Life Without Light
• Chemosynthesis:
– Chemical energy is
used to produce
sugars
• Chemosynthetic
organisms are found
in the deepest,
darkest oceans, hot
springs, and tidal
marshes.
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Heterotrophs
• Many organisms cannot directly use
energy from the environment.
• They must acquire energy from other
organisms
– They are known as heterotrophs
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Consumers
• Organisms that rely on other organisms for
energy and nutrients are called consumers
• There are different classes of consumers
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Consumers
• Decomposers:
– “feed” by chemically
breaking down organic
matter
– Ex: fungi, bacteria
• Detritivores:
– Feed on detritus
particles (waste, trash)
– Ex: earthworms,
beetles
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Consumers
• Scavengers:
• Omnivores:
– Consume the
carcasses of other
animals
– Ex: vultures,
– Diet naturally includes
a variety of different
foods.
– Both plants and
animals
– Ex: humans, bears,
pigs
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Consumers
• Herbivores
• Carnivores
– Eat plants, roots,
seeds, or fruits
– Ex: cows, caterpillars,
and deer
– Kill and eat other
organisms
– Ex: snakes, cats,
dogs, etc
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Population Dynamics
• Three Key Features of Populations
– Size
– Density
– Dispersion
Three Key Features of Populations
• Growth Rate:
– Birth Rate (natality) - Death Rate (mortality)
– How many individuals are born vs. how many die
– Birth rate (b) − death rate (d) = rate of natural
increase (r)
Three Key Features of Populations
Density: measurement of population per unit
area or unit volume
Pop. Density = # of individuals ÷ unit of space
How Do You Affect Density?
1.
Immigration: movement of individuals into a population
2.
Emigration: movement of individuals out of a population
3.
Density-dependent factors: Biotic factors in the
environment that have an increasing effect as population
size increases (disease, competition, parasites)
4.
Density-independent factors: Abiotic factors in the
environment that affect populations regardless of their
density (temperature, weather)
Factors That Affect Future Population Growth
Immigration
Natality
+
+
Population
Emigration
-
Mortality
Carrying Capacity
• Carrying Capacity (k):
– The maximum population size that can be
supported by the available resources
– There can only be as many organisms as the
environmental resources can support
How Do Populations Grow?
•
Idealized models describe two kinds of
population growth:
1. Exponential Growth
2. Logistic Growth
The Human Population
• Doubled three times in the last three centuries
• About 6.1 billion and may reach 9.3 billion by
the year 2050
• Improved health and technology have lowered
death rates
Energy
• Energy flows in a one-way stream from
primary producers to various consumers
through the food chain
Food Chains
• Food chains are series of steps in which
organisms transfer energy by eating and
being eaten
• Producer  Herbivore  Carnivore
Food Webs
• Feeding relationships
are usually more
complex than just a
simple chain
• Many animals eat more
than one kind of food
• Complex networks of
feeding relationships
are called food webs.
Trophic LevelsCarnivores/omnivores
• Each step in a food
chain or food web is
called a trophic
level
Carnivores/
• “nourishment omnivores
level”
herbivores
autotroph
s
Energy Pyramid
• Shows the amount of
energy available at each
trophic level of a food
chain or food web.
• Only a small portion of
energy in each trophic
level makes it to the
next level
– 10% rule
Between each trophic level 90% of energy is lost to the
atmosphere as heat. Only 10% of energy is transferred
from one level to the next.
Ecological Pyramids
Pyramid of Numbers
Shows the individual number of organisms
at each trophic level.
Biomass Pyramid
Measures the total dry mass of
organisms at
each trophic level.
What is Ecological Succession?
• Natural, gradual changes in the
types of species that live in an
area
• Can be primary or secondary
• The gradual replacement of one
plant community by another
through natural processes over
time
Primary Succession
• Begins in a place without any soil:
»Sides of volcanoes
»Landslides
»Flooding
• First, lichens that do not need soil to
survive grow on rocks
• Next, mosses grow to hold newly
made soil
• Known as PIONEER SPECIES
Secondary Succession
• Begins in a place that already has
soil and was once the home of
living organisms
• Occurs faster and has different
pioneer species than primary
succession
• Example: after forest fires
Climax Community
• A stable group of plants and
animals that is the end result of
the succession process
• Does not always mean big trees
–Grasses in prairies
–Cacti in deserts
Aquatic Ecosystems
• The types of organisms
that live in an aquatic
ecosystem is determined
by the water’s salinity
• Salinity is the amount of
dissolved salts the water
contains.
– Freshwater= <0.5 ppt
– Saltwater= 30-50 ppt
• Aquatic Ecosystems are
divided into Freshwater
and Saltwater or Marine
Freshwater vs Saltwater
 Freshwater
 Lakes and Ponds-Slow
 Rivers and Streams-Fast
 Wetlands-water logged land
 Marshes and Swamps
 Saltwater or Marine
 Marshes and SwampsCoastal
 Coral Reefs
 Deep Oceans
Characteristics of Aquatic Ecosystems
 Aquatic Ecosystems are characterized by
 Temperature
 Sunlight Depth
 Oxygen Concentration
 Available Nutrients
 Aquatic Organisms are grouped by their location at water
depths and adaptations
 Plankton-Surface, provide most of food, producers
 Zooplankton-microscopic animals
 Phytoplankton-microscopic plants
 Nekton-Free swimming organisms
 Fish, Turtles, Whales
 Benthos-Bottom dwelling organism, lived attached to
hard surfaces
 Mussles, worms and Barnacles
Lakes and Ponds
• Form naturally where ground water
reaches the Earth’s surface
• Humans and animals like beavers
create lakes and ponds by
interrupting water flow
• Lake structure-2 zones
– Littoral Zone-Surface, Sunlight
• Aquatic Plants and Animal
– Benthic Zone-Bottom, Dark
• Bacteria, Decomposers, Bottom
Feeding Fish
• Animal Adaptations-Whiskers on
Catfish to find food on the bottom,
Amphibians burrow into the mud in
winter to avoid freezing
Wetlands
 Areas of land covered by water for
part of the year
 2 Types of Wetlands
 Marshes-contain nonwoody plants such
as cattails, low, flat lands, characterized
by salinity-ex. Florida Everglades
 Swamps-dominated by woody plants
such as cypress trees, low, poorly
drained land, good habitat for
amphibians- ex. Louisiana bayou
 2 Purposes of Wetlands
 Filter and absorb water-prevents
pollutants from entering ground water
 Control Flooding-absorb river overflow
 Homes and nesting area for migratory
birds
 Cranberry, crawfish production
Wetlands are protected in many states
Rivers
• Originate from snow melt in the
mountains of Minnesota 1475 ft
above sea level
• 2320 miles long, flows southward
in meanders, terminating 95
miles below New Orleans at sea
level or O ft.
• 4th longest river in the world
• Changes with the land and
climate through which it travels
– Higher altitudes-cold, narrow, fast,
oxygen rich-Head Waters
• Trout, Minnows, Moss
– Lower altitudes-warmer, wider,
slower and decreased dissolved
oxygen-Ends in a fan shape called
the Delta
• Plankton, Carp, Catfish
• Arrowhead, Crowfoot
Threats to River Systems
• Industries use river water in manufacturing
processes and release waste into the waters.
• Water runoff from land carries pesticides,
fertilizers and manufacturing chemicals into the
river coating sediment with toxic waste
• Pollutants enter ground water and human
drinking water resources in rural areas.
Biodiversity encompasses
several levels
• Humans are reducing Earth’s
diversity of life
• Biodiversity – sum total of all
organisms in an area
– Split into three specific levels:
• Species diversity
• Genetic diversity
• Ecosystem diversity
Species diversity
• Species Diversity = the number or variety of
species in the world or in a particular region
– Richness = the number of species
– Evenness or relative abundance = extent to which
numbers of individuals of different species are
equal or skewed
– Speciation generates new species and adds to
species richness
– Extinction reduces species richness
• Encompasses
the differences
in DNA among
Genetic
diversity
individuals within species and populations
• The raw material for adaptation to local
conditions
• Populations with higher genetic diversity can
survive
– They can cope with environmental change
• Populations with low genetic diversity are
vulnerable
– To environmental change
– Disease
– Inbreeding depression = genetically similar
parents mate and produce inferior offspring
Ecosystem diversity
• Ecosystem diversity = the number and
variety of ecosystems
• Also encompasses differing communities
and habitats
• Rapid vegetation change and varying
landscapes within an ecosystem promote
higher levels of biodiversity
Biodiversity losses and species
extinction
• Extinction = occurs when the last member of a
species dies and the species ceases to exist
• Extirpation = the disappearance of a particular
population from a given area, but not the entire
species globally
– Can lead to extinction
Earth has experienced five mass
extinctions
• In the past 440 million years, mass extinctions have
eliminated at least 50% of all species
• After every mass extinction the biodiversity returned to or
exceeded its original state
Current extinction rates are higher
than normal
• The Red List = an updated list of species facing
high risks of extinctions
– 23% of mammal species
– 12% of bird species
– 31 - 86% of all other species
• Since 1970, 58 fish species, 9 bird species, and 1
mammal species has gone extinct
– In the U.S., in the last 500 years, 236 animal and 17
plant species are confirmed extinct
– Actual numbers are undoubtedly higher
Biodiversity loss has many causes
• Reasons for biodiversity losses are
multifaceted, complex, and hard to determine
– Factors may interact synergistically
• Four primary causes of population decline are:
–
–
–
–
Habitat alteration
Invasive species
Pollution
Overharvesting
• Global climate change now is the fifth cause
Invasive species cause biodiversity
loss
• Introduction of non-native species to new environments
– Accidental: zebra mussels
– Deliberate: food crops
• Island species are especially vulnerable
• Invaders have no natural predators, competitors, or parasites
• Cost billions of dollars in economic damage
Biodiversity provides free ecosystem
services
• Provides food, shelter, fuel
• Purifies air and water, and detoxifies wastes
• Stabilizes climate, moderates floods, droughts, wind,
temperature
• Generates and renews soil fertility and cycles nutrients
• Pollinates plants and controls pests and disease
• Maintains genetic resources
• Provides cultural and aesthetic benefits
• Allows us to adapt to change
The annual value of just 17 ecosystem services = $16 - 54 trillion per
year
Conservation biology responds to
biodiversity
loss
• Conservation biology
= devoted to
understanding the
factors that influence
the loss, protection, and
restoration of
biodiversity
– Arose as scientists
became alarmed at the
degradation of natural
systems
– An applied and goaloriented science
Should conservation focus on
endangered species?
• Endangered Species Act (1973) (ESA) = forbids the
government and private citizens from taking actions
that destroy endangered species or their habitats
– To prevent extinction
– Stabilize declining populations
– Enable populations to recover
• As of 2007, the U.S. had 1,312 species listed as
endangered or threatened
Protecting biodiversity
• Captive breeding – individuals are bred and raised
with the intent of reintroducing them into the wild
– Zoos and botanical gardens
• Some reintroductions are controversial
– Ranchers opposed the reintroduction of wolves to
Yellowstone National Park
– Some habitat is so fragmented, a species cannot
survive
Umbrella species
• Conservation biologists use particular species as tools to
conserve communities and ecosystems
– Protecting the habitat of these umbrella species helps protect
less-charismatic animals that would not have generated public
interest
• Flagship species – large and charismatic species used as
spearheads for biodiversity conservation
– The World Wildlife Fund’s panda bear
• Some organizations are moving beyond the single species
approach to focus on whole landscapes
Biodiversity hotspots
• Biodiversity hotspots –
prioritizes regions most
important globally for
biodiversity
– Support a great number of
endemic species = species found
nowhere else in the world
– The area must have at least 1.500
endemic plant species (0.5% of the
world total)
– It must have lost 70% of its habitat
due to human impact