Chapter 13 - Evolution Notes

Question 1

What did Aristotle believe about species?

Answer 1

Believed that species were unchanging, and that there was a hierarchy of life forms of increasing complexity
-> Known as the scala naturae

Question 2

Carolus Linnaeus

Answer 2

Created the binomial naming system (taxa)

i.e. kingdom, phylum, class, order, family, genus, species

Question 3

Georges Cuvier

Answer 3

“The father of palaeontology”

The first to document that the history of life on earth was recorded in layers of rock.

Proposed the theory of catastrophism:
Each layer of rock represents a different catastrophe

Question 4

James Hutton

Answer 4

Proposed the theory of Gradualism:
Changes in the earths crust were the cumulative product of slow but continuous processes

Question 5

Charles Lyell

Answer 5

Proposed the theory of uniformitarianism:
Geological processes are so uniform that their effects must be balanced out through time.

2 conclusions:
- Geological change results from slow continual processes, not sudden events.
- Earth must be very old

Question 6

Jean Baptiste Lamarck

Answer 6

Came up with the first theory of evolution.

He compared fossil collections with those of this living species today. He could see what appeared to be several lines of descent.

He also theorized that organisms react to their environment and that this can influence their heritable traits.
(inheritance of acquired characteristics)

Question 7

Charles Darwin

Answer 7

(The father of evolution)

Published “The Origin of Species” which was risky since evolution was not widely accepted.

He defined evolution as “decent with modification” meaning natural selection.

Question 8

Artificial selection

Answer 8

Humans modifying other species by selecting and breeding individuals with desired traits over many generations.

Question 9

2 basic observations of natural selection:

Answer 9

1. Members of a population often vary in their inherited traits.
2. All species are capable of producing more offspring than the environment can support.

Question 10

2 inferences about natural selection:

Answer 10

1. Individuals who have a higher survival and reproducing probability tend to leave more offspring than other individuals.
2. The unequal production of offspring will lead to the accumulation of favourable traits in a population of generations.

Question 11

3 key points to know both natural selection:

Answer 11

1. Individuals do not evolve, populations do.
2. Natural selection can only amplify or diminish heritable traits.
3. Evolution is not goal oriented. It does not lead to perfectly adapted organisms.

Question 12

Fossil

Answer 12

A preserved remnant or impression of an organism that lived in the past.

Note: organism with hard bodies are better represented in fossil records

Question 13

Casts

Answer 13

When organic material of the organism decays, but leaves a mould of the organism in sediments, which can be filled by minerals dissolved in water

Question 14

Trace fossils

Answer 14

Include things such as footprints, burrows, and other remnants of an ancient organisms behaviour.

Question 15

The fossil record

Answer 15

The sequence in which fossils appear within layers of sedimentary rock provides some of the strongest evidence for evolution. When fossils are arranged in order of their age, a progressive series of changes can be seen.

Question 16

What were some of the condition of early earth?

Answer 16

• no oxygen
• no ozone layer
• lots of UV, toxic gases, volcanoes, lightning (like venus)

Question 17

Stromatolites

Answer 17

Rock-like formations built up by ancient photosynthetic bacteria. Some are still around today

Question 18

Phylogeny

Answer 18

The evolutionary history of a species or group of related species

Question 19

Phylogenetic tree

Answer 19

A branching diagram that represents a hypothesis about the evolutionary history of a group of organisms.

Can attempt to show how organisms are related

Question 20

What are the hypothesized 4 main stages of how simple cells were produced?

Answer 20

1. The abiotic synthesis of small organic molecules
2. Joining of these molecules into polymers.
3. Packing of the organic molecules into protocells.
4. The origin of self replicating molecules that eventually made inheritance possible. (RNA)

Question 21

Panspermia

Answer 21

The theory that life on earth originated from microorganisms or chemical precursors of life present in outer space

Ex. A meteorite

Question 22

The Archaean eon

Answer 22

4.6 - 2.5 bya

• contained only prokaryotic life (approx. 3.9 bya)
• Oxygen begins to appear slowly which killed some of the prokaryotes, while others harvested the oxygen for cellular respiration.

Question 23

Proterozoic eon

Answer 23

2.5 bya - 542 mya

• first eukaryotic cells began appearing (approx 2.1 bya)
• small multicellular eukaryotes appear (approx. 1.5 bya)

Question 24

The Phanerozoic

Answer 24

542 mya - present

Note: up until this eon, all life existed in the water

• larger forms of life began colonizing land (approx. 500 mya)
• the Cambrian explosion reveals complex animals

Question 25

Snowball earth theory

Answer 25

A hypothesized period of severe ice ages which covered all of the planets land masses . Life did continue, but only in the water not on land.

(Approx. 750 - 580 mya)

Question 26

The Cambrian explosion

Answer 26

Cambrian period (535 - 525 mya)

The appearance of many of the major phyla that make up modern animal life. (Prior to this, all large animals were soft bodied)

Question 27

Continental drift

Answer 27

Theory that the continents once were a giant continent called pangaea which eventually split into 2 called Laurasia and Gondwana, then split again into out 7 continents.

This is caused by the mantel of the earths crust which is very hot and somewhat pliable so the continents were able to shift on top of it.

Question 28

Tectonic plates

Answer 28

The earths crust is divided into irregularly shaped plates that float on the underlying mantle.

Ex. We live in the North American plate.

Question 29

Subduction

Answer 29

Opposite of sea floor spreading

When two plates come together, the lighter one is pushed up, and the heavier one is pushed down into the hot mantle where the rock melts and volcanos form.

When these volcanoes erupt it causes earthquakes (usually in the ring of fire)

Question 30

Sea floor spreading

Answer 30

Opposite of subduction

Occurs when two tectonic plates separate and magma from the mantle rises to fill the forming gap

This creates a ridge at the bottom of the ocean. (Widens the sea floor)

Question 31

The Permian extinction

Answer 31

Occurred 251 mya

This is the largest mass extinction which wiped out 96% of marine species and 70% of terrestrial species.

It was caused by massive increase in volcanic activity, which released enough CO2 to warm the globe by ≈6°, causing oxygen reduction and ocean acidification.

Question 32

The cretaceous extinction

Answer 32

Occurred 66 mya

Triggered by a meteor that hit the Caribbean Sea. This left a crater 180 km wide and ejected immense amount of material into the atmosphere, which blocks sunlight and stoped photosynthesis, and created an acid rain.

Question 33

Adaptive radiation

Answer 33

An event which causes a lineage to thrive and diversify by gaining new adaptations.

Ex. Mammals after the dinosaurs went extinct.

Question 34

How do we date fossils?

Answer 34

Radiocarbon dating - using the decay of carbon isotopes to determine the age of a fossil sample.

Isotope: C14 has a half life of 5730 years (so after 5730 years, a dead organism contains half of the original C14 it had, after another half year it will have a fourth of what it originally had so it is 11, 460 years old…etc)