Evolution Flashcards
Darwin’s theory
Evolution by natural selection
Mutations
Those better adapted characteristics towards an environment increase survival chances which increases likelihood of survival
These then get passed on
Lamarck’s theory
Characteristics that are used evolve
Eg giraffe neck or rabbits legs
These are then passed on to offspring
Acquired characteristics passed on
Eg muscular dad to baby
Disagreements with darwin’s theory
Went against religious beliefs
No good explanation- Dna took another 50 yrs
Not enough evidence as not many other studies had been carried out
A hypothesis
Needs evidence to be accepted
Types of relationships
Evolutionary
(Genes having a common ancestor)
Ecological
( environment- in competition or a predator prey relationship)
Fossils are what
The remains of organisms from many thousands of years ago
Provide evidence that such organisms existed
Can tell about evolution
Gradual replacement
things like teeth shells and bones don’t decay very easily but when they do they’re replaced with minerals forking a Rock like substance shaped like the original part- surrounding sediment also turns to rock but fossils stay distinct inside the rock
Casts or impressions
When an organism is buried in a soft material like clay
Clay later gardens around it and organism decays
Forms a cast of the organism
Things like footprints can be pressed leaving an impression also
Preservation
In places where no decay occurs
- in amber and tar pits there’s no oxygen or moisture so decay microbes can’t survive
- in glaciers temps are too cold so decay microbes don’t work
- in peat bogs they’re too acidic for decay microbes
Why do we not know how life on Earth began?
Many early life forms were soft bodied and soft tissues tends to decay completely
Fossil record incomplete
Some fossils may have been destroyed by geological activity (eg tectonic plates)
Extinction happens when
Evolution doesn’t occur quickely enough
Reasons for the extinction of a species
Environmental changes are too quick (destruction of habitat)
A new predator
A new disease
Cannot compete with other species for food
Catastrophic event- volcanic eruption or meteor collision
A new species (speciation)
What is a species
A group of similar organisms that can reproduce to give fertile offspring
What is speciation
The development of a new species
Occurs when populations of the same species become so different that they can no longer breed together to produce fertile offspring
What is isolation
Where populations of a species are separated
