MacroevolutionMacroevolution

The Beginning…The Beginning… Scientists have tried to figure out the initial conditions and

events that may have resulted in the origin of life, however, this research is ongoing as scientists test hypotheses about origins and evolution.

We believe that Earth was formed about 4.6 billion years ago It was extremely hot. Heat generated by asteroid impacts,

internal compression and radioactivity melted most of the rocky material on Earth. Heavy materials formed Earth’s inner core and less dense materials formed a thick mantle, while the least dense rock floated on the surface and cooled to form a crust.

Scientists have tried to figure out the initial conditions and events that may have resulted in the origin of life, however, this research is ongoing as scientists test hypotheses about origins and evolution.

We believe that Earth was formed about 4.6 billion years ago It was extremely hot. Heat generated by asteroid impacts,

internal compression and radioactivity melted most of the rocky material on Earth. Heavy materials formed Earth’s inner core and less dense materials formed a thick mantle, while the least dense rock floated on the surface and cooled to form a crust.

Hot gases formed Earth’s primitive atmosphere, then when the amount of asteroids hitting Earth slowed down, the surface temperatures were able to cool down.

Early Earth would have contained large amounts of nitrogen gas, CO2, carbon monoxide and water vapour.

Because oxygen gas is highly reactive, and the temperatures were very high, there would be very little, if any oxygen gas in the atmosphere.

There were some amounts of other vapours on primordial Earth such as hydrogen sulfide, ammonia, and methane.

Hot gases formed Earth’s primitive atmosphere, then when the amount of asteroids hitting Earth slowed down, the surface temperatures were able to cool down.

Early Earth would have contained large amounts of nitrogen gas, CO2, carbon monoxide and water vapour.

Because oxygen gas is highly reactive, and the temperatures were very high, there would be very little, if any oxygen gas in the atmosphere.

There were some amounts of other vapours on primordial Earth such as hydrogen sulfide, ammonia, and methane.

There were a lot of intense sources of energy: radioactivity, intense UV, visible light, cosmic radiation, heat from volcanic activity, and electrical from violent lightning storms.

Primary abiogenesis is a theory that the first living things on Earth arose from nonliving material.

Urey and Miller were two scientists who tested the theory by putting a few inorganic materials together that would be found on primordial Earth, and exposed them to electrical sparks, which actually modeled the early conditions of Earth. Their results were that after only one week, 15% of the original carbon had formed into aldehydes, carboxylic acids, urea and two amino acids.

There were a lot of intense sources of energy: radioactivity, intense UV, visible light, cosmic radiation, heat from volcanic activity, and electrical from violent lightning storms.

Primary abiogenesis is a theory that the first living things on Earth arose from nonliving material.

Urey and Miller were two scientists who tested the theory by putting a few inorganic materials together that would be found on primordial Earth, and exposed them to electrical sparks, which actually modeled the early conditions of Earth. Their results were that after only one week, 15% of the original carbon had formed into aldehydes, carboxylic acids, urea and two amino acids.

Chemical evolution is believed to have taken place and organic materials came together with the amount of heat that was available; it gave rise to more complex polymers and organic substances.

These molecules went through self-replication and catalytic activity.

Chemical evolution is believed to have taken place and organic materials came together with the amount of heat that was available; it gave rise to more complex polymers and organic substances.

These molecules went through self-replication and catalytic activity.

Scientists believe that life has existed on Earth for more than 3.5 billion years.

The first prokaryotic organisms would have relied on abiotic sources or organic compounds: chemoautotrophs

The first photoautotrophs would come next, and they used water to “breathe” by taking off the Hydrogen and releasing the oxygen into the atmosphere.

This accumulation of oxygen would have been toxic to many anaerobic organisms, so while the photoautotrophs prospered, cells adapted to this change, others died.

Scientists believe that life has existed on Earth for more than 3.5 billion years.

The first prokaryotic organisms would have relied on abiotic sources or organic compounds: chemoautotrophs

The first photoautotrophs would come next, and they used water to “breathe” by taking off the Hydrogen and releasing the oxygen into the atmosphere.

This accumulation of oxygen would have been toxic to many anaerobic organisms, so while the photoautotrophs prospered, cells adapted to this change, others died.

The Tree of LifeThe Tree of Life Macroevolution is large scale evolutionary

change significant enough to classify groups or lineages into distinct genera or even higher level taxa.

This macroevolution has been punctuated by times of mass extinction as well as times of very rapid diversification.

A lineage is the descendants of a common ancestor

Macroevolution is large scale evolutionary change significant enough to classify groups or lineages into distinct genera or even higher level taxa.

This macroevolution has been punctuated by times of mass extinction as well as times of very rapid diversification.

A lineage is the descendants of a common ancestor

Endosymbiosis (relationship in which a single-celled organism lives within the cell of another organism) is another important theory that scientists proposed that suggests that may have given rise to chloroplasts and mitochondria.

for the first 3 billion years of life on Earth, all organisms were unicellular.

Eubacteria gave rise to aerobic and photosynthetic lineages.

Endosymbiosis (relationship in which a single-celled organism lives within the cell of another organism) is another important theory that scientists proposed that suggests that may have given rise to chloroplasts and mitochondria.

for the first 3 billion years of life on Earth, all organisms were unicellular.

Eubacteria gave rise to aerobic and photosynthetic lineages.

Diversification and Mass ExtinctionDiversification and Mass Extinction Earth’s History is divided into 5 eras based on dramatic changes in the

fossil record. There was a 40 million year period beginning about 640 million years

ago where there was a huge increase in animal diversity called the Cambrian explosion

Major changes in the Earth have been caused by numerous events. Formation of super continent “Pangea” would have caused coastal

and terrestrial environments as well as changes in the global climate.

Huge asteroids hitting Earth (Impact hypothesis) causing tidal waves, debris, high concentrations of different materials.

Earth’s History is divided into 5 eras based on dramatic changes in the fossil record.

There was a 40 million year period beginning about 640 million years ago where there was a huge increase in animal diversity called the Cambrian explosion

Major changes in the Earth have been caused by numerous events. Formation of super continent “Pangea” would have caused coastal

and terrestrial environments as well as changes in the global climate.

Huge asteroids hitting Earth (Impact hypothesis) causing tidal waves, debris, high concentrations of different materials.

Mass extinction periods are only 4% of all extinctions, however, and we must remember that extinctions usually happen due to the ongoing evolutionary changes.

Mass extinction periods are usually followed by periods of huge diversification.

Mass extinction periods are only 4% of all extinctions, however, and we must remember that extinctions usually happen due to the ongoing evolutionary changes.

Mass extinction periods are usually followed by periods of huge diversification.

Cladistics and PhylogenyCladistics and Phylogeny Cladograms are used to illustrate

evolutionary relationships of different groups of species.

Based on evidence from fossils, morphology, genetics.

Use the presence or absence of recently evolved traits called derived traits.

Two organisms that share a recently evolved trait is called a synapomorphy.

Cladograms are used to illustrate evolutionary relationships of different groups of species.

Based on evidence from fossils, morphology, genetics.

Use the presence or absence of recently evolved traits called derived traits.

Two organisms that share a recently evolved trait is called a synapomorphy.

CladogramsCladograms Page 351, try the sample problem and

the practice question.

Page 351, try the sample problem and the practice question.

GradualismGradualism

The theory of gradualism states that as new species evolve, they appear very similar to the original species and only gradually become more distinctive.

The theory of gradualism states that as new species evolve, they appear very similar to the original species and only gradually become more distinctive.

Punctuated EquilibriumPunctuated Equilibrium

The theory of punctuated equilibrium suggests that the process of evolution is slow, but occasionally punctuated by periods of rapid change.

The theory of punctuated equilibrium suggests that the process of evolution is slow, but occasionally punctuated by periods of rapid change.

Now it is widely accepted that both gradualism and punctuated equilibrium play a significant role in evolution.

When there is a quick change in the environment: rapid evolution

environment changes slowly: gradual

Now it is widely accepted that both gradualism and punctuated equilibrium play a significant role in evolution.

When there is a quick change in the environment: rapid evolution

environment changes slowly: gradual