Download Chapter 5 Ecosystems and the Living Environment

By: Mariama Koroma and Bethiel
Fesseha
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Charles Darwin proposed the
mechanism that is accepted today
“Survival of the Fittest” – inherited
traits favorable to survival in a given
environment tend to be preserved, and
unfavorable ones are eliminated
Adaptation: evolutionary modification
that improves chances of survival and
reproductive success of the population The Origin of Species by Means
in a given environment
of Natural Selection
•More favorable genes
increase in successive
generations, and fewer
unfavorable genes survive
1.
2.
3.
4.
Overproduction: more offspring produce than will
survive to maturity
Variation: individuals have unique combinations of traits
that make them more/less “fit” for their environment
Limits to Population Growth(Struggle for Survival):
environment can’t support everyone (Competition for
resources, predation, or disease)
Differential Reproductive Success: Those individuals
with the most “fit” traits for their environment are more
likely to survive, reproduce, and pass their traits on to the
next generation
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Directional Selection: One extreme of a specific trait is
more advantageous than both the other extreme and
average trait
 Ex. Peppered Moth
 “Pays to be DIFFERENT”
Stabalizing Selection: Tends to eliminate individuals on
both ends of the genetic spectrum
 Ex: Birth Weight
 “Pays to be AVERAGE”
Diversifying (Disruptive) Selection: environmental
conditions favor individuals at both extremes of the genetic
spectrum and eliminate or sharply reduces individuals with
intermediate genes
 Ex: Green v. Brown Anole
 “Pays to be (either) EXTREME”
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Convergent Evolution: two totally different species
become similar due to their same type environment for
each species
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Divergent Evolution: two of the same species move to
different environmental and evolve to two different
species
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Ex. Dolphin and Sharks
Ex: Penguin and Puffin
Adaptive Radiation: Darwin’s Finches
Co-Evolution: A form of evolution where two different
species evolve in the same fashion
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Ex: Rabbit and Wolf
Super Subject 4:
Succession- the gradual change in species that occupy a given area
Primary Succession:
originates from a
lifeless habitat (bare
rock, lava flow, etc.)
Secondary
Succession:
occurs where a
disturbance
eliminates most
organisms but
does not
destroy soil
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Early
 GPP is LOW because: LOW PRODUCER DENSITY
 R is LOW because: LOW PRODUCER DENCITY & FEWER PRODUCERS
 NEP is MEDIUM meaning: MASS IS ACCUMULATING; SYSTEM IS
GROWING
Middle
 GPP is MEDIUM because: MEDIUM PRODUCER DENSITY
 R is MEDIUM because: MEDIUM PRODUCER DENSIT AND MEDIUM # OF
PRODUCERS CAN SUPPORT MORE CONSUMERS
 NEP is MEDIUUM meaning: MASS IS STILL ACCUMULATING; SYSTEM IS
STILL GROWING
Late: CLIMAX COMMUNITY
 GPP is HIGH because: HIGH PRODUCER DENSITY
 R is high because: HIGH PRODUCER AND MANY CONSUMERS CAN
NOW BE SUPPORTED
 NEP is LOW meaning: STABLE COMMUNITY, NOT GROWING;
PRODUCTION RESPIRATION RATIO APPROACHES 1
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Keystone Species: Species that are more crucial to the maintenance of their
ecosystems, vital in determining the nature and structure of the entire
ecosystem (not most abundant organisms)
Symbiotic Relationships
 Mutualism (+/+): both organisms benefit Ex. Nitrogen Fixation Bacteria
and Legumes
 Commensalism (+/0): one benefits, one is not affected Ex. Remora Fish and
Shark
 Parasitism (+/-): one benefits, one is harmed Ex. Tapeworm and Human
Predation: consumption of one species (prey) by another (predator)
 Strategies (Pursuit and Ambush)
 Adaptations for Plants: spines thorns, tough leaves, protective chemicals
 Adaptations for Animals: fight, camouflage, mechanical & chemical
defenses
 Warning Coloration & Mimicry: Ex. Monarch and Viceroy Butterflies
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Niche: role of an
organism in their
ecosystem- “its job”
Includes abiotic and
biotic factors
NO TWO
SPECIES CAN
SHARE THE
SAME NICHE!
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Fundamental VS.
Realized Niche
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Limiting Factors: forces that slow the growth of a
population
Density Dependent: dependent on population size;
related to competition. (ex. Food supply, living space, and
water availability)
 Density Independent: affects the same % of a
population regardless of size (ex. Climate and natural
disasters)
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Competition: Intraspecific VS Interspecific
Intraspecific: competition within two individuals of the
SAME species; Ex. A big cardinal and a little cardinal
fight for the same seed
 Interspecific: competition between two DIFFERENT
species; Ex. Cardinals and Finches compete for same bird
seed
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Factors that affect species richness:
1. Abundance of potential ecological niches
2. Proximity to margins of adjacent communities
- ECOTONE= transitional zone where 2 or more
communities meet
3.
4.
5.
6.
Geographical Isolation
Dominance of one species over others
Habitat Stress
Geological History
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Summary: Species richness is great when…
There are MANY potential ecological niches
 You’re CLOSE TO adjacent communities
 The community isnot isolated
 The community isnot severely stressed
 There is LOW species dominance over others
 Communities have STABLE geologic history
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