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.
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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.