ES: Community Ecology, Population Ecology, and Sustainability Chapter 6.
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Transcript of ES: Community Ecology, Population Ecology, and Sustainability Chapter 6.
ES: Community Ecology, Population Ecology, and
Sustainability
Chapter 6
KEY IDEAS
• What determines the number of species in a community?
• How classify according to roles in community?• How do species interact?• Communities respond to environmental changes?• How do reproductive patterns differ in species?
Human Impact?• How do Niches Change?• Sustainability?• Natural Capital?
Lets talk Niche
NICHE and ADAPTATIONS (4.3) & ( 6.3)
• A Niche is an organisms role in the ecosystem. It affects it and others survival and reproductive Fitness(reproduction)
• No two organisms occupy the same niche
• Habitat: Where it lives
Niche: Fundamental and Realized • Realized the actual
range available due to competition
• Fundamental• Full potential range
that can theoretically used
Chthamalus : fundamentally could live in many zones. Balanus moves him out.
NICHE
Fundamental niche
• Describes the potential a species has to be completely successful in using its resources to the fullest extent without competition,predation, or pressure from limiting factors.
Realized Niche
• Describes what a species is actually going to do in terms of using its resources due to pressures from limiting factor s ,predation, or competition
Exclusion of an organisms nicheCompetitive Exclusion or interspecific exclusion
• Competition between two species forms exclusion of each other . They Competitively exclude one another out of a niche .One of the competitors always overcomes the other.
• New niche may form or evolutionary shift or extinction
Intraspecific Exclusion
• When the same species exclude each other it is Intraspecific Exclusion.
• Niches Overlap
Competitive exclusion
When the same species exclude each other it is Intraspecific Exclusion
The woodpecker • Males characteristically
forage on small trees or on small branches of large trees
• females typically forage on the trunks and larger limbs of large trees.
• The niches overlap, but the slight distinction limits competition between the sexes
• So long as there are enough resources species can share them.
Can lead to adaptations or radiation of the species
Radiation of the Species: adaptations form from competition creating
speciation – new species
Resource Partitioning reduces or avoids competition
• Specialized traits evolve that allows them to share resources at different
• Times -temporal• Ways- Ways they get
food• places - different areas
of same resource
One tree many resources
Speciation:Formation of a species through competition,
limiting factors, and adaptations
Resource partitioning summary: forms adaptations that cause specialization and new niches
Limiting Factors ?DDLF – DDIF?
Density Dependent Limiting factors (DDLF)
• Limiting factors that are intensified by the density of populations
Are typically bioitc factors
Competition
Bacterial disease
Symbiosis-species relationships
Density Independent Limiting factors(DILF)
• Limiting factors that are NOT intensified by population numbers
Are typically abiotic factors
Climate
Natural disasters
Viral disease
6.1 Community Structure and Species Diversity
• Physical Appearance – Sizes, stratification and distribution of species (pg 110)
Physical Appearance lends to species richness and evenness as physical appearance changes
Community Structure is Zoned. Zones are Wide and Varied due
to many factors
Aquatic Zones affected by temperature, amount of light, salinity,pressure,
Some other Factors cause these variances: Sunnier, warmer, drier, lighter, darker,moister, acidic,
salinity,biomass abundant…
Zoned Life is Patchy….
(directly from your book!)
Community structure also varies around its edges where transitions of communities take place.
Human Impact: Habitat Fragmentation
• Increases forest edge or buffers: Makes species more vulnerable to stresses like predators, fire, and creates barriers where species cannot colonize and finding food.
Species Diversity and Niche Structure
Species Richness (number of species)
Species Evenness (number of individuals within species) = Species Diversity
Allows community a to differ from b to differ from c………
Typically a community is either rich or even but not both!
Species Diversity Types Species Richness The
number of species in an areas of each species present. This is rrsity
How rich are the species in your area?
Species Evenness : how many of each species exists in that areanumber of members How even is the diversity?
Rainforest, coral reef , deep sea, large tropical lakes have high species diversity but low species evenness (few members in each)
IF: Species A = 56 members Species B = 55 members
Species C = 52Then: species evenness is good but diversity is low!
DIVERSITY CREATES NICHE STRUCTURE
• Highest in tropics and declines as move North and south from equator
Are Complex Communities more sustainable than Simple ones?
Typically: Net Primary productivity indicates ecosystem is more resilient with species diversity of 30 -4 0 (complex) However, not conclusive, and still a hot environmental topic. Some believe simple communities have just enough diversity to survive.
Agree: All communities need producers and decomposers .which producers and which are essential is the question.
Species Types 6.2
6.2 Species Types
• Native:Normally • live and thrives
in area
Has competitors and
Natural predators
Non-Native,Invasive, Alien
Have Migrated or been deliberately or accidentally transferred into an area
Some have no effect: corn, chickens
Indicator Species Think : Range of Tolerance
Indicator SpeciesBiological smoke alarms
• Fish, birds, amphibians, butterflies
• Indicate ecosystem health: pH, Habitat fragmentation, dissolved oxygen in water communities, pollution, reduction in stratospheric ozone, climate change, over hunting…
Amphibians as an Indicator Species
• Habitat loss-defragmentation
• Prolonged Draught• Pollution – pesticides• UV Radiation• Parasites• Overhunting• Viral/Fungal diseases• Non-native
predators/competitors
WHY CARE?
• 1st – environmental health deterioration
• 2nd – Amphibians eat more pests and feed many others
• 3rd – They are genetic storehouse of pharmaceuticals
• Painkillers, antibiotics, burn treatment
(biopharming)
Keystone Species
A wedge shaped stone placed in an archway supporting the entire arch
IF REMOVED: DRAMATIC !!!!
Ecological Services go out all over
Keystone Species• Have a huge effect on the species
richness and evenness of an ecosystem.
• A keystone species disappears can lead to population crashes and extinction.
Keystone Niche
• Pollination• Regulation/control
population• Remove, Bury,
Recycle (dung it anyway!)
• Biopharming
Foundation Species: Create and enhance habitat in ways that benefit others
• Trimming Trees• Rolling over rocks• Tearing trees out by
roots• Planting
6.3 Species InteractionsKey Concept: Increase
ability to survive through
Competition and Symbiotic Relationships
Competition
• Abundant Resources personify fundamental niche
• Non abundant causes a more realized niche
• Humans deprive species of resources causing more realized niches occupation
• Interspecific
Competition
Can we Reduce or Avoid Competition? Competition allows
for1.Adaptations through
Natural Selection2.Predator/Prey Relationship
Prey on the least fit
3.Keeps populations in check not to exceed resources
How do predators increase their chances of catching prey?
• Lie in wait
• Persue
• Camoflage
Can Prey Defend Themselves?
• Escape
• Pretective shells
• Camoflage
• Mimicry
• Chemicals
Parasites Sponge Off Each Other
• Parasite (sponger) • Host (spongee)
Other symbiotic relationships
• Mutualistic:
• Commensalistic:
• Parasitic
• Both benefit ++
• One benefits other is neither harmed or benefits +0
• One benefits the other is harmed +-
6.4 Ecological Succession
Change of Producers mass Over Time
Terrestrial Succession
Aquatic Succession
Succession
• PRIMARY
Gradual establishment of biotic communities on newly exposed rock
No soil, No bottom sediment
Receding ice bergs
New Lava Flows
• SECONDARY
On existing soil, or bottom sediment
Reestablishment of any Cleared area due to
Fires, tornados, tsunamis, human impact
Is this primary or secondary succession?
From Pioneer Species to Intermediate Species, to a Climax
CommunityPrimary: initial, does not need
much soil or waterIntermediate species: need some
soil, water, sunClimax community: needs more soil
and other factors
Can we Predict Succession?Not Always
An ever changing mosaic of vegetation patches
On going struggle by species for resources
Climax Community: Mature community for that climate
6.5 Population Dynamics and Carrying Capacity
• Enter: Births, immigration, and decrease in deaths
• Exit: Death, emigration
51
© 2004 Brooks/Cole – Thomson Learning
Time (t) Time (t)
Po
pu
lati
on
siz
e (N
)
Po
pu
lati
on
siz
e (N
)
K
Exponential Growth is J shaped: rarely keeps going
Logistic Growth: levels off is S shaped.
Figure 9-4Page 193
Growth is never just exponential only – it reaches carrying capacity and levels off
Overshoot of Carrying Capacity• Occurs when births are
greater than deaths
• Humans not exempt
Then causes a ‘dieback’ or ‘crash’
• Polynesians on Easter Island
Carrying Capacity is ecosystems maximum ability to support populations. Directly
related to producer biomass and climate
54
Exponential vs. Logistical Growth Curves
• Lag Phase—First portion of the curve; slow population growth.
• Exponential Growth Phase—More organisms reproducing causing accelerated growth; continues as long as birth rate exceeds death rate.
• Stable Equilibrium Phase—Death rate and birth rate equilibrate; population stops growing; achieved in logistical growth curves
55
Population Growth Curve
Reproductive PatternsR and K Strategies
Some species have few offspring and take care of them until they care for themselves
K Selected Species
( K = competitor)
Some have many and care-less
R-selected species
(R means Rapid)
57
Reproductive Strategies and Population Fluctuations
• Not all species reach a stable carrying capacity.
• Species can be broadly lumped into two categories:– K- strategists- competitor species; they do well
in competitive situations where population size is close to or at carrying capacity; logistical growth
– R-strategists- have a high intrinsic rate (r) of increase; exponential “boom & bust” cycles of growth
Reproductive StrategiesWhich one has a greater Range of Tolerance?
• K-selected: mature slowly have few offspring at a timemost endangered species are K-
selectedpopulation stabilizes near carrying
capacitymaintain numbers in stable
ecosystemsDo well in competitive conditionsSpecialist NicheLate Succession dwellersHigh ability to competeLivestockMammals
• r-selected: mature rapidly have many offspring - tend to
overproduce Die before reach maturity population not regulated by
density opportunistic -- invade new areasGeneralist NicheEarly Succession dwellerslow ability to competeopportunistsCropsAlgaelBacteria
Depends on the available habitat determines success!
6.6 Human Impact on Ecosystems
• Where Natural Systems would allow re-growth, reuse,recycling, and be
renewable…Man doesn’t and is less forgiving ,simplifying biodiversity, Using up non-renewable energy, producing much waste, wastes rather than recycles
and uses, destroys, or degrades Net Productivity
Ie: (doesn’t share with others well)
Principles of Sustainability
Follow Nature - Four Ways
Nutrient Cycling -Renewable Resources Especially Energy and waste
Solar Energy
Use Biodiversity to maintain itself and adapt
Control population size and resource use