Download Ch.18 Notes - Green Local Schools

Ecology Intro
Ch.18
(18-1) Ecology
• Study of interactions b/w the living &
nonliving parts of the environment
• Collect info about organisms &
environments, look for patterns, & try to
explain those patterns
Today’s Issues
• Survival used to depend on practical
knowledge
• Humans have changed the environment
more than ever in the past few decades
Exploding Human Population
• Rapid increase of humans on Earth
• Downfalls: severe crowding, requires
more E, food, & space for waste
disposal
6th Mass Extinction
• As humans increase, the # of species
decrease
• Species disappearing at a faster rate now
than last mass extinction (dinosaurs)
• Estimated that 1/5 of species may
disappear in the next century
Thinning Ozone Layer
• Ozone protects Earth from the sun’s UV
light
• CFCs & other chemicals are destroying
it
• Hole over Antarctica
Climatic Changes
• Greenhouse effect: inc. in CO2 caused
inc. in reflected heat towards Earth
– CO2 from burning fossil fuels
• Causing global warming
Key Theme
• Interconnectedness (interdependence)
– No organism is isolated
– Survival depends on interactions
– Disturbances can effect the entire network
Ecological Models
• Visual, verbal, or mathematical
• Ecosystems are complex & difficult to
study
• Use to help understand & make
predictions
5 Levels of Organization
1. Biosphere
•
•
Earth & atmosphere that supports life
Broadest, most inclusive
5 Levels (cont.)
2. Ecosystem
•
•
All organisms & the nonliving found in a
particular place
Ex: pond - fish, algae,
bacteria, O2, CO2, pH
5 Levels (cont.)
3. Community
•
•
All interacting organisms living in an area
No nonliving parts
4. Population
•
All members of a species that live in 1
place at 1 time
5 Levels (cont.)
5. Organism
– Simplest level
– Study the adaptations that organisms
develop to survive
(18-2) Factors
• Biotic: living
• Abiotic: nonliving
– Temp., humidity, pH, sunlight, O2
• Habitat: where organism lives
Tolerance Curve
• Performance vs. environmental variable
(ex: temp.)
• Organism can’t live in areas outside its
tolerance curve
Acclimation
• Adjust tolerance to abiotic factors
– Ex: adjust to higher elevation
– Occurs w/in an organism’s lifetime
• Adaptation: genetic change in a
species or pop. that occurs over many
generations
Control of Internal Conditions
• Conformers: do not regulate their internal
conditions; change as their external
environment changes
– Ex: lizard body temp.
• Regulators: use E to control some of their
internal conditions
– Ex: human body temp.
Escape from Unsuitable
Conditions
• Dormancy: reduced activity
– Ex: reptiles & amphibians hide in winter
• Migration: move to more favorable
habitat
– Ex: seasonal movements of birds
Resources
• E & materials the species needs
• Ex: food, E, nesting sites, water, &
sunlight
Niche
• Way of life; role the species plays in the
environment
• Fundamental niche: all conditions a
species can tolerate & resources it can
use
• Realized niche: range of resources it
actually uses
• Avoid predators, competition
Niche Differences
• Generalists: species w/ broad niches
– Ex: opossum, rat
• Specialists: species w/ narrow niches
– Ex: koala
(18-3) E Transfer
•
Goals:
1. Contrast b/w producers & consumers
2. Explain the important role of
decomposers in an ecosystem
3. Contrast a food chain w/ a food web
4. Explain why an ecosystem
usually contains only a few
trophic levels
Energy
• Need E to maintain homeostasis, grow,
reproduce, etc.
• Determines how many & what kind of
organisms live in an ecosystem
Producers
• Sun is the ultimate source of E
• Producers use sun E to make “food” E
for themselves & for the consumers
• Chemosynthesis: produce carbs by
using E from inorganic molecules
– bacteria
Measuring Productivity
• Gross primary productivity: rate at which
producers capture E
• Net primary productivity: rate at which
biomass (organic material) accumulates
– Varies from 1 ecosystem to another
Consumers
• Herbivores: eat producers
– Antelope, deer
• Carnivores: eat other consumers
– Lions, bald eagles, cobras
• Omnivores: eat both
producers & consumers
– Grizzly bear
Consumers (cont.)
• Detrivores: feed on “garbage” of
ecosystem
– Vulture
• Decomposers: cause decay by breaking
down dead tissues & wastes
– Bacteria, fungi
E Flow
• Trophic level: organism’s position in the
sequence of E transfers
– 1st: producers (autotrophs)
• Largest
– 2nd: herbivores
– 3rd & above: all other consumers
• Smallest
Ecosystem Implications
• ~10% of the total E consumed in 1 trophic
level is passed on to the next level
– Usually no more than 4 or 5 levels
Food Chain
• Single pathway of feeding relationships
in an ecosystem
Food Web
• Diagram of the
interrelated food
chains in an
ecosystem
• More accurate
description of the
ecosystem
Can you now answer these
questions?
1. Contrast b/w producers & consumers
2. Explain the important role of
decomposers in an ecosystem
3. Contrast a food chain w/ a food web
4. Explain why an ecosystem usually
contains only a few trophic levels
(18-4) Ecosystem Recycling
• Biogeochemical cycle: process where
nutrients are circulated through the
environment
Water Cycle
• Evaporation
– Transpiration: plants take in H2O through
their roots & release H2O & take in CO2
through stomata
• Condensation: cloud formation
• Precipitation
• Returned back into the cycle
Water Cycle
Carbon Cycle
•
•
•
•
Cellular respiration
Photosynthesis
Combustion
Death &
decomposition
Nitrogen Cycle Terms
• Nitrogen fixation: converting N2 gas to
ammonia
– N-fixing bacteria
• Denitrification: N compounds are broken
down & N2 gas is returned to
atmosphere
Nitrogen Cycle
Phosphorus Cycle
• Needed by animals to form bones,
teeth, RNA, & DNA
• Plants get it from soil & water
• Animals get it from eating plants