Plate Tectonics Rift Valleys

Rift Valleys are created by continental plates that drift apart. They typically for deep lakes, seas, or new lands.

The new lands and bodies of water drive speciation.

Hot SpotsNot actually made

by continental plates, but rather magma that breaks through the ocean crust.

However movement of plates over hot spots can create chain of islands.

Ecosystem Stability and SuccessionOrganisms can colonize isolated areas by:

AirSeaAnimal

Specific Types of DispersalJump Dispersal

Long-distance dispersal to remote area by few individuals.

Diffusion Spread of a species from the edge of their

range into a new area

Secular MigrationDispersal over long time period. Evolutionary

changes to species while diffusing into new area.

Process of Primary Succession Primary Succession- The formation of an

ecosystem from bare rock.1. Pioneer species arrive and colonize bare rock.

Soil is created when species die.2. New plant growth changes environment.3. Plants needing soil arrive, using their roots to

retain the soil.4. Physical conditions change again5. New species arrive (more complex and

larger).6. Animals arrive in search of food sources. 7. Climax community is reached.

Secondary SuccessionSuccession that occurs in an area that already

has soil. Can be caused by human activities or natural

processes (natural disasters). Succession can be halted at any time and the

climax community may not be reached.A Sere is the set of communities that succeed

one another over the course of succession at a given location.

DisturbanceThree factors determine the ability of an

ecosystem to recover after an disturbance:Inertia- or persistence, resistance to being

altered,Resilience- ability of a system to recover after

a disturbance,Diversity- the number and proportions of

species present.

Disturbance Contin.A complex ecosystem that has complex food

webs allow animals and plants to respond to disturbances in many ways, thus providing an high inertia.

Ecosystems with high resilience have nutrient-rich soils, which promote new growth.

Case Study Disturbance of Grass PrairieThe tall grass prairie in the US provided a high

diversity, complex ecosystem that maintained stability.

The prairie would recover quickly following fires because of the high build up of organic matter.

Farming has replaced the native ecosystem, causing low diversity, inertia, and soils that need to be maintained artificially.

Loss of DiversityNatural disasters

have lead to periods of diversity loss in the past.

Changes in Earth’s orbit and tilt and plate movements have lead to repeated long-term cold periods.

Factors of Diversity Loss

Natural disastersHabitat degradationAgricultural practicesIntroduction of non-native speciesHunting, collecting, and harvesting

Tropical RainforestConsists of emergent layer, canopy layer,

understory layer, ground layer. Considered “biodiversity hotspot”

50% of plant species, 42% terrestrial vertebrates.

DeforestationSome species live in the upper layer for

entire life e.g.. Rhacophorus gadingensis (tree frog)

Thin, nutrient-poor soils Difficult to regrow (sometimes!)

Green PoliticsAn ideology which places an importance on

ecological and environmental goals.Through broad-based, grassroots, and

participatory democracy. Stimulated in part by the threats to rainforests.

Principle goal- to obtain sustainable development by reducing deforestation and encouraging reforestation.

Anti-capitalism an important feature

Present and Past ExtinctionsThere have been five mass extinctions

Mass extinction- a large proportion of the total number of species on the Earth at one time are wiped out.

Earth is undergoing the sixth mass extinction, believe to be caused by human activities.

Extinctions Cretaceous-Tertiary

(65 million years ago)End Triassic (199 –

214 million years ago)Permian-Triassic (251

million years ago)Late Devonian (364

million years ago)Ordovician-Silurian

(439 million years ago)

Impact of an asteroid or gradual climate change and flood-like eruptions.

Massive floods of lavaLargest event,

suspected asteroid or flood volcanism.

Unknown cause.Drop in sea levels as

glaciers formed and then rising sea levels as glaciers melted.

Our Current SituationThe evolution of life and the mass extinctions has

wiped out 99 percent of all species that have lived on Earth.

Sixth ExtinctionFirst abiotic extinctionPhase 1 began 100,000 years ago when humans

dispersed to different parts of the world.Phase 2: 10,000 years ago when humans turned

to agriculture. Over-population, invasive species, over-

exploitation, global warming, pollution Before 100 species lost per year, now 27,000.

Factors that Make Species Prone to Extinction

Small size and limited distribution Island species

Habitat specialist Specific diet or habitat

requirements

Low reproductive capacity Live long time

Poor competitors Lack of mobility or defensive

instincts

Large mammals Significant source of meat

and large amounts of resources

Valuable products Value as pets, ceremonial

objects, food

Altruistic species Preserve bonds to frighten off

predators

Clumping Large numbers

Position of food chain Higher up = more

vulnerability

Determining Conservation Status (Red Data Book)

Population sizeQueen of the Andes

Reduction in population sizeEuropean Eel

Number of mature individuals

Geographic range and degree of fragmentationPeacock Parachute

Tarantula

Quality of habitatArea of occupancy Probability of

extinction

Case Study Extinct Falkland Island WolfEcological Role

Lived in burrows Diet – ground-nesting

birds, grubs, insects, and seashore scavenging.

Pressures Settlers had sheep

which were being killed by the wolves.

Wolf was easily maneuvered into a trap

Consequence of disappearance Not a significant

predator, may have had impact on food chain

Critically Endangered: Iberian LynxEcological Role

Specialized feeder (rabbits) and often kill other carnivore species, but does not eat them.

Pressures Highly specialized

diet, small geographic area, habitat destruction. Not allowed to hunt after 1970s.

Methods of restoring populationPublic awareness

and education programs changed attitudes. Captive breeding program that allow reintroduction into the wild.

Improved by Intervention: Bald Eagle

Ecological Role Live near large

bodies of water and have specific territories for nesting. Eat small animals and primarily fish.

Pressures Population

plummeted in 1950s (hunting, pesticides on crops, destruction of habitat, contamination of waterways and food sources, and DDT).

Methods of restoring population DDT was outlaws

in 1970s. Created Acts for

the Eagles and were considered endangered (no hunting).

Natural Area Threatened: The Great Barrier ReefHuman threats

TourismOver-fishing Water pollution

(fertilizers, pesticides, sewage)

Global warming Natural threats

Predators and diseases

Storms and cyclones Coral bleaching

Consequences Irreversible damage Loss of

biodiversity and valuable role in ecosystem (erosion in mangroves and sea-beds) leads to reduction in its value.

Pages 202-205

Arguments for Preserving Species and HabitatsBiodiversity can be

difficult to quantify.Good harvested from

the ecosystem are easier to evaluate than indirect values.

Value of the ecosystem depends on cultural background and economic status.

Economic Values of BiodiversityEasy economic value

Natural productsFood

Difficult economic valueEconomic productivityEnvironmental

indicators Scientific reasonsEducationGenetic diversityRecreation and

ecotourismAesthetic valueHuman rightsEthical reasons

Conservation OrganizationsNon-governmental Organizations (NGOs)- not

run by, or funded by, or influenced by governments of any country. Tend to be more radical and field-based.

Intergovernmental Organizations (GOs)- are bodies established through international agreements to protect the environment and bring together governments to work on an international scale. Tend to be more conservative.

Conservation OrganizationsNGO GOUse of Media

Advertise, leaflets, press packs

Speed of ResponseRapid and regular, own

decisionsDiplomatic Constraints

Unaffected by politics, may be illegal

Political InfluenceNo direct influence

Enforceability Rely on public pressure, no

power to enforce laws

Use of MediaProfessional liaison officers,

international news clips Speed of Response

Must meet legal requirements of several countries

Diplomatic Constraints Cannot give opinion w/out

lawyer, disagreements cause serious constraints

Political InfluenceDirect access to many

countries Enforceability

Through international agreements and laws

International Conventions on BiodiversityIUNC (World Conservation Union),

concerned with conservation of resources for sustainable economic development, has three agendas:Maintaining ecological processesPreserving genetic diversityUsing species and ecosystems in a

sustainable fashion.

International Conventions on Biodiversity

IUNC established World Conservation Strategy, which outlined series of global priorities for action and recommended that account the conservation of natural resources for long-term human welfare.

Drew attention to a fundamental issue: the importance of making the users of natural resources become their guardians.Stressed that without understanding the

local community and support, the strategies cannot succeed.