What are fossils
The preserved remains of plants and animals whose bodies were buried in sediment. They are also any trace of life over 10, 000 years old
What is the fossil record?
A collection of fossils documenting the history of life on earth
What can the fossil record tell us
About an extinct organisms size, shape and/or behaviour
What is relative dating
Used to determine approximate age by comparing it to similar rocks and fossils of known ages
What is absoloute dating
used to determine precise age of a a fossil though radiometric dating to measure the decay of isotopes
What are the types of fossils
Preserved remains: Fossils that have been protected from decay by being buried rapidly in sediments or other materials like ice or amber.
Trace Fossil: Marks left by an animal or plant, eg. nests, burrows, footprints.
Mold Fossil: They preserve a three-dimensional impression of remains buried in sediment, eg. shells or leaves.
Cast Fossil:Replica of an ancient organism formed when mineral-rich water or sediment fills a pre-existing mold
Petrified Fossil: Where the original organic material of an organism is replaced by minerals, turning it into stone.
Carbon Film: When an organism is compressed under heat and pressure, leaving behind a thin film of carbon residue
What kind of fossils are found in rocks
Index
How are rocks used to identify the age of fossils
If the same index fossil is found in different strata far apart, the layers likely formed around the same time
What is carbon dating
a scientific method that can accurately determine the age of organic materials as old as approximately 60,000 years
How does carbon dating work
Carbon dating estimates how long the organism has been dead by counting the carbon-14 atoms
What is evolution?
Changes in the heritable traits of a population of organisms as successive generations replace one another.
Evolution:
What types of traits are passed through generations?
Only advantageous ones, from a common ancestor.
Does evolution occur in the population of an organism or in individual organisms?
Population
What is speciation?
When a group within a species separates from other members of its species and develops its own unique characteristics.
How does speciation impact biodiversity?
As it creates new species from a common ancestor, it can increase diversity.
What was Darwin’s conclusion about the Galapagos finches?
All the finches orginated from a common ancestor from the mainland of South America.
As the finches adapted to different island environments on Galapagos (selection pressure), they developed diverse phenotypes of beak shapes, claw types and sizes, which varied from the mainland species and from each other.
What is natural selection
Natural selection is the process where an environmental factor, favours a particular phenotype that is better suited to the conditions.
Over time the genotypes that produce the advantageous phenotypes will become more common in the population.
Eg. An elongated neck for giraffes
Example of natural selection
Darwins finches
What is artificial selection, provide an example
Identification by humans of the desirable traits in plants and animals and the steps taken to enhance and perpetuate those traits in future generations
Human interference with evolution, for their own benefit not the benefit of the species.
eg dog breeds
What is variation
Variation refers to the differences observed among individuals within a species
Differences between natural and artificial selection
Natural
- Humans are not involved
- More generations are involved = slower process
- Survival of the fittest: increases species chance for survival
- Mutations that result in natural selection occur randomly
Artificial
- Human intervention
- Selective breeding is faster
- Adaptations may not necessarily improve survival
- The desirable characteristics are artificially chosen
What are the evidence for evolution?
- Fossils: shows a progression of life forms, particulalrly through transitional fossils that are connected to modern animals showing how animals have evolves over time.
- Comparative anatomy: the presence of homologous structures indicates shared ancestry.
- Embryo Development: studying the embryo of different species can show a shared ancestor
- DNA structure: high degree of similarity in DNA and protein sequences among related species and how closely species are related and how long ago they diverged.
What are homologous structures?
These are body parts that share a common ancestry, even if they have evolved to serve different functions in different species.
Example of homologous structure
For example, the forelimbs of humans, bats, and whales have a similar bone structure, reflecting their shared origin from a common ancestor, but they are used for different purposes (grasping, flying, swimming).
