Evolution Flashcards
(25 cards)
What is evolution
The theory that explains how millions of different species have developed over billions of years from one common ancestor
Common ancestor
An organism from which other have evolved
When did a simple life from that first ever developed happen
More than three billion years ago
What is a theory
A rational explanation that can be used to form a hypothesis to test
Who proposed the natural selection theory
An English scientist called Charles Darwin
What is natural selection
The process where living things that are more adapted to the environment are more likely to survive and reproduce
What leads to biodiversity
Adaptations formed for different regions - hot or cold
What is Charles Darwin often called
The father of evolution
What is a characteristic
A phenotypic feature such as length of fur
What does natural selection act on
The phenotype
Is natural selection always occurring
Yes
Definition of species
A group of organisms that can interbreed to have fertile young
What can cause new species to form
Natural selection
What is evolution
The change in a species over a long time
Why did theory of evolution face criticism at first
Because some believed in creationism
What are fossils
The remains of organisms from millions of years ago, found preserved in rocks
Three ways fossils are formed
- When parts of dead organisms do not decay
- When parts of the organism are replaced by minerals when decay
- When an organism leaves traces or tracks
How are fossils formed 1st way
Some fossils are formed when parts of dead organisms do not decay because the condition have kept the specimen preserved. In a peat bog there is no oxygen and the water has a low pH to stop decaying microorganisms breaking down the body.
How are fossils formed 2nd way
When parts of the organism are replaced by minerals as they decay. This happened when organism has been covered with layers of sand, volcanic ash or the silt from the bottom of rivers and seas. The layers above them push down, compressing the organism. The surrounding surrounding eater id squeezed out, leaving behind mineral salts which turn to stone
How are fossils formed 3rd way
When an organism leaves preserved traces or tracks. Such as dinosaur footprints of eggs. Burrows of some organisms have also been found
What is the fossil record
The information of all the fossils that have been discovered so far
What is the date of many fossils estimated by
Looking at the layers of rock in which the fossils are found
Example of natural selection and evolution in humans
Originally horses were smaller and had bigger feet to stop them getting stuck in the marshes. As the marshes started to dry up, it was the individuals with smaller hooves that had the evolutionary advantage. They could run away from predators faster because they had smaller feet. The fossil record shows this gradual change to smaller hooves.
Why are there gaps in the fossil record
Not all fossils have been found yet.
Many fossils would have been destroyed in hot volcanic lava.
Many organisms have died and were not preserved which may be because their body were made of soft tissue and not bone.
