4.6.3.2 Speciation (biology only)

Question 1

Speciation:

Answer 1

• the process of a new species developing through the selection of different alleles
• this increases genetic variation until the new population cannot breed with those in the old population to produce fertile offspring

Question 2

What did Alfred Russel Wallace propose?

Answer 2

• Alfred Russel Wallace independently proposed the theory of evolution by natural selection
• he published joint writings with Darwin in 1858 which prompted Darwin to publish ‘On the Origin of Species’ (1859) the following year

Question 3

How did Alfred Russel Wallace work?

Answer 3

• Wallace worked worldwide gathering evidence for evolutionary theory - on his travels he had the idea that individuals who did not have the characteristics to help them survive a change would die out
• Alfred Russel Wallace did much pioneering work on speciation but more evidence over time has led to our current understanding of the theory of speciation

Question 4

What is Alfred Russel Wallace’s best known work?

Answer 4

best known for his work on warning coloration in animals and his theory of speciation

Question 5

Process of speciation:

Answer 5

1. Variation exists within a population as a result of genetic mutations
2. Alleles which provide a survival advantage are selected for through natural selection
3. Populations of a species can become isolated e.g. through physical barriers preventing them from breeding together
4. Different alleles may be advantageous in the new environment, leading to them being selected for
5. Over time the selection of different alleles will increase the genetic variation between the 2 populations
6. When they are no longer able to breed together to produce fertile offspring a new species has formed

Question 6

Causes for new species to arise:

Answer 6

• genetic variation - each population has a wide range of alleles that can control their characteristics
• natural selection - the alleles which help an organism to survive are selected in each population
• speciation- the populations become extremely varied and successful interbreeding cannot happen anymore
• isolation

Question 7

How can new species arise through isolation?

Answer 7

• two populations of a species can become geographically separated because of the environment
• isolation can prevent interbreeding and the combination of genes within a species
• different mutations can take place in the isolated groups and create different phenotypes within a particular location
• over time species may evolve to be different to each other, and they will not be able to interbreed