Please enable JavaScript.
Coggle requires JavaScript to display documents.
4.1 Darwin and Wallace's Theories and 4.2 Evolution by Natural…
4.1 Darwin and Wallace's Theories and 4.2 Evolution by Natural Selection
Alfred Russel Wallace
He published joint studies with Darwin
The publication of ‘On the Origin of Species’ meant Darwin received the credit for the theory
On his travels, he had the idea that the individuals who did not have characteristics to help them survive a change in the environment would die out
He continued to work across the world to collect evidence – one of his most important works was on warning colouration in animals
Alfred Russel Wallace developed the theory of speciation, and therefore evolution by natural selection
Much more evidence over time has resulted in our current understanding
The Process of Speciation
Alleles which provide a survival advantage are selected for through natural selection
Populations of a species can become isolated, for example through physical barriers such as a rock fall preventing them from breeding together
Variation exists within a population as a result of genetic mutations
Different alleles may be advantageous in the new environment, leading to them being selected for
Over time the selection of different alleles will increase the genetic variation between the two populations
When they are no longer able to breed together to produce fertile offspring, a new species has formed
Charles Darwin
Put forward the theory of evolution
This was supported by experimentation and his knowledge of geology and fossils that he discovered on a round the world expedition
Scientist and naturalist
Published ‘On the Origin of Species’ in 1859
Theory of Evolution
Organisms with characteristics most suited to the environment are more likely to survive to reproductive age and breed successfully – called survival of the fittest
The beneficial characteristics are then passed on to the next generation
Variation exists within species as a result of mutations in DNA
Over many generations the frequency of alleles for this advantageous characteristic increase within the population
Controversy
It contradicted the idea that God was the creator of all species on Earth
There was not enough evidence at the time as few studies had been done on how
organisms change over time
There was lots of controversy surrounding his ideas for many reasons
The mechanism of inheritance and variation were not known at the time