Plate TectonicsPlate Tectonics

Plate tectonicsPlate tectonics

A theory that states that the earth’s crust is A theory that states that the earth’s crust is made up of a number of plates which move made up of a number of plates which move over a liquid crust that get created and over a liquid crust that get created and destroyed over time. destroyed over time.

Moving PlatesMoving Plates The force for these movements is derived from The force for these movements is derived from

magmatic convection cells in the magmatic convection cells in the asthenosphere of the mantle. asthenosphere of the mantle.

The upward portion of these cells are known The upward portion of these cells are known as as magmatic plumes.magmatic plumes.

When they hit the crust, the plate above is When they hit the crust, the plate above is melted and forced to spread creating a melted and forced to spread creating a spreading ridgespreading ridge as they are adding new as they are adding new continental material (constructive margin) to continental material (constructive margin) to the edges of these plates. the edges of these plates.

Evidence supporting plate tectonicsEvidence supporting plate tectonics

Ages of oceanic crusts get older as one moves away Ages of oceanic crusts get older as one moves away from a spreading ridge. from a spreading ridge.

Ages of oceanic sediments on top of the crust gets Ages of oceanic sediments on top of the crust gets older as one moves away from a spreading ridge. older as one moves away from a spreading ridge.

Rock formations with the same mineral content and Rock formations with the same mineral content and age existing on opposite continental shores. The age existing on opposite continental shores. The eastern most tip of south America and the African eastern most tip of south America and the African Congo both have the same iron ore rock formation. Congo both have the same iron ore rock formation. Rock formations are also shared between Rock formations are also shared between Newfoundland, Canada and the west coast of Ireland Newfoundland, Canada and the west coast of Ireland and southern India and South Africa. and southern India and South Africa.

Evidence supporting plate tectonicsEvidence supporting plate tectonics

Stationary hot-spots "burn" trails into moving Stationary hot-spots "burn" trails into moving continents. continents.

Magnetic anomalies showing variations in the Magnetic anomalies showing variations in the Earth’s magnetic field strength are arranged in Earth’s magnetic field strength are arranged in bands parallel to each other on either side of bands parallel to each other on either side of the spreading ridges. the spreading ridges.

Evidence supporting plate tectonicsEvidence supporting plate tectonics

Magnetic polarity reversals patterns are Magnetic polarity reversals patterns are preserved as the rock formed, show symmetry preserved as the rock formed, show symmetry about spreading ridges. about spreading ridges.

The margins or edges of some continents have The margins or edges of some continents have shapes that indicate that they once fit together. shapes that indicate that they once fit together. (i.e. South America fitting into Africa.)(i.e. South America fitting into Africa.)

Evolution and Biodiversity Evolution and Biodiversity Influenced by Plate ActivityInfluenced by Plate Activity

PangeaPangea

Two hundred million years ago (Ma), research Two hundred million years ago (Ma), research suggests that all the continents where one large suggests that all the continents where one large mass which was named Pangea. mass which was named Pangea.

Terrestrial organisms were able to migrate Terrestrial organisms were able to migrate across all the continents and were only limited across all the continents and were only limited by their biotic potential. by their biotic potential.

BiodiversityBiodiversity As Pangea began to separate into separate As Pangea began to separate into separate

continents 130 Ma, creating physical barriers continents 130 Ma, creating physical barriers such as seas, restricting migration to within the such as seas, restricting migration to within the continents. continents.

Gene pools of species are separated and as Gene pools of species are separated and as they are exposed to different physical (i.e. they are exposed to different physical (i.e. climate) and biotic (i.e. change in predators) climate) and biotic (i.e. change in predators) conditions, each portion of the species adapts conditions, each portion of the species adapts differently and eventually forms new species differently and eventually forms new species on the separated continents. on the separated continents.

This process is known as This process is known as speciationspeciation. .

BiodiversityBiodiversity

Changes in physical and biotic conditions will Changes in physical and biotic conditions will also lead to the creation of new species also lead to the creation of new species increasing the diversity of habitats and niches. increasing the diversity of habitats and niches.

This also provides the space for new species to This also provides the space for new species to evolve into these habitats. evolve into these habitats.

The end result of the separation of Pangea into The end result of the separation of Pangea into today’s continental configuration is that plate today’s continental configuration is that plate tectonics has been one of the main driving tectonics has been one of the main driving forces promoting biodiversity or organisms. forces promoting biodiversity or organisms.

BiodiversityBiodiversity In addition to continents separating, some like India In addition to continents separating, some like India

left south Africa and Antarctica and joined up with left south Africa and Antarctica and joined up with Asia. Asia.

It took with it organisms that were typical to It took with it organisms that were typical to Antarctica and Australia. Antarctica and Australia.

Over the next 100 Myrs these organisms evolved in Over the next 100 Myrs these organisms evolved in isolation from any other continent until it formed a isolation from any other continent until it formed a land bridge with Asia. land bridge with Asia.

Since 30 Myrs ago the species on India and Asia have Since 30 Myrs ago the species on India and Asia have been re-adapting themselves causing additional been re-adapting themselves causing additional biodiversity. biodiversity.

BiodiversityBiodiversity Australia has one of the most unique sets of organisms as it Australia has one of the most unique sets of organisms as it

and Antarctica have been separate from all the other and Antarctica have been separate from all the other continents for the last 130 Myrs. continents for the last 130 Myrs.

Australia separated from Antarctica about 50 Myrs ago. Australia separated from Antarctica about 50 Myrs ago. This extreme isolation over such a long period of time This extreme isolation over such a long period of time

supports Darwin’s theory of evolution in that this part of the supports Darwin’s theory of evolution in that this part of the world has the most unique organisms. world has the most unique organisms.

Australian species have had such limited contact with species Australian species have had such limited contact with species from other continents that they have only needed to adapt to from other continents that they have only needed to adapt to their particular set of species and climate. their particular set of species and climate.

No re-adaptation to other species from other continents has No re-adaptation to other species from other continents has occurred until the arrival of the Europeans. occurred until the arrival of the Europeans.

BiodiversityBiodiversity

The splitting up of Pangea 200 million years The splitting up of Pangea 200 million years ago had the following effects on species ago had the following effects on species diversity and distribution.diversity and distribution.

a) Species gene pools or populations a) Species gene pools or populations where split as Pangea separated.where split as Pangea separated.

b) New habitats were created due to a b) New habitats were created due to a change in biotic and abiotic factors such as change in biotic and abiotic factors such as climate (temperature and moisture), changes in climate (temperature and moisture), changes in species relationships, and topography.species relationships, and topography.

BiodiversityBiodiversity

c) New niches were made available and filled causing further c) New niches were made available and filled causing further adaptation of species to new conditions thus modifying the adaptation of species to new conditions thus modifying the local ecosystem.local ecosystem.

d) Species relationships change with respect to mutualism, d) Species relationships change with respect to mutualism, predation, and competition. Species need to modify food predation, and competition. Species need to modify food source, protection, and dependence patterns in the food source, protection, and dependence patterns in the food web.web.

e) Speciation: is the creation of a new species when a gene e) Speciation: is the creation of a new species when a gene pool of one species is split, exposed to new conditions to pool of one species is split, exposed to new conditions to which each pool adjusts to. Different genetic traits are which each pool adjusts to. Different genetic traits are passed on to offspring. A new species evolves once the 2 passed on to offspring. A new species evolves once the 2 original populations cannot mate. original populations cannot mate.

BiodiversityBiodiversity

Rejoining of plates such as India and Asia. 30 Ma ago caused Rejoining of plates such as India and Asia. 30 Ma ago caused the following.the following.

a) Migration of one species into the territory of another a) Migration of one species into the territory of another introduces new forms of competition and predation that introduces new forms of competition and predation that existing species need to adapt.existing species need to adapt.

b) Further speciation is generated and modified as they b) Further speciation is generated and modified as they

come into contact with a variation of the original gene pool.come into contact with a variation of the original gene pool.

BiodiversityBiodiversity

Extreme isolation such as Australia and Antarctica. Extreme isolation such as Australia and Antarctica. 130 Ma of isolation.130 Ma of isolation.

a) As no new predators are introduced over a a) As no new predators are introduced over a long period of time speciation is limited to changes in long period of time speciation is limited to changes in abiotic factors such as climate and topography. abiotic factors such as climate and topography.

b) Evolution tends to slow down and become b) Evolution tends to slow down and become more specialized if there are fewer stresses and more specialized if there are fewer stresses and ecosystem changes.ecosystem changes.

c) Species evolve separately from original gene c) Species evolve separately from original gene pool and tend to be very different from other areas pool and tend to be very different from other areas with more contact with the original gene pool. with more contact with the original gene pool.