Chapter 13 - Evolution Notes Flashcards
What did Aristotle believe about species?
Believed that species were unchanging, and that there was a hierarchy of life forms of increasing complexity
-> Known as the scala naturae
Carolus Linnaeus
Created the binomial naming system (taxa)
i.e. kingdom, phylum, class, order, family, genus, species
Georges Cuvier
“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
James Hutton
Proposed the theory of Gradualism:
Changes in the earths crust were the cumulative product of slow but continuous processes
Charles Lyell
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
Jean Baptiste Lamarck
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)
Charles Darwin
(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.
Artificial selection
Humans modifying other species by selecting and breeding individuals with desired traits over many generations.
2 basic observations of natural selection:
- Members of a population often vary in their inherited traits.
- All species are capable of producing more offspring than the environment can support.
2 inferences about natural selection:
- Individuals who have a higher survival and reproducing probability tend to leave more offspring than other individuals.
- The unequal production of offspring will lead to the accumulation of favourable traits in a population of generations.
3 key points to know both natural selection:
- Individuals do not evolve, populations do.
- Natural selection can only amplify or diminish heritable traits.
- Evolution is not goal oriented. It does not lead to perfectly adapted organisms.
Fossil
A preserved remnant or impression of an organism that lived in the past.
Note: organism with hard bodies are better represented in fossil records
Casts
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
Trace fossils
Include things such as footprints, burrows, and other remnants of an ancient organisms behaviour.
The fossil record
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.
What were some of the condition of early earth?
- no oxygen
- no ozone layer
- lots of UV, toxic gases, volcanoes, lightning (like venus)
Stromatolites
Rock-like formations built up by ancient photosynthetic bacteria. Some are still around today
Phylogeny
The evolutionary history of a species or group of related species
Phylogenetic tree
A branching diagram that represents a hypothesis about the evolutionary history of a group of organisms.
Can attempt to show how organisms are related
What are the hypothesized 4 main stages of how simple cells were produced?
- The abiotic synthesis of small organic molecules
- Joining of these molecules into polymers.
- Packing of the organic molecules into protocells.
- The origin of self replicating molecules that eventually made inheritance possible. (RNA)
Panspermia
The theory that life on earth originated from microorganisms or chemical precursors of life present in outer space
Ex. A meteorite
The Archaean eon
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.
Proterozoic eon
2.5 bya - 542 mya
- first eukaryotic cells began appearing (approx 2.1 bya)
- small multicellular eukaryotes appear (approx. 1.5 bya)
The Phanerozoic
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
Snowball earth theory
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)
The Cambrian explosion
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)
Continental drift
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.
Tectonic plates
The earths crust is divided into irregularly shaped plates that float on the underlying mantle.
Ex. We live in the North American plate.
Subduction
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)
Sea floor spreading
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)
The Permian extinction
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.
The cretaceous extinction
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.
Adaptive radiation
An event which causes a lineage to thrive and diversify by gaining new adaptations.
Ex. Mammals after the dinosaurs went extinct.
How do we date fossils?
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)
