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

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© 2004 Brooks/Cole – Thomson Learning

Time (t) Time (t)

Po

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on

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Po

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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

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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

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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)

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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