Speciation and Evolution

The formation of a new species is called speciation. Two populations of the same species may become geographically isolated. Both populations are then exposed to different selection pressures due to changes in temperature for example. The populations respond to these selection pressures and this causes random mutations to occur. These mutations are passed onto offspring through natural selection when the populations reproduce. This causes the population to become less and less like each other, especially as these random mutations accumulate in the gene pool and their allele frequency increases. 

Should the two groups meet again, they would be unable to reproduce to produce fertile offspring and they are considered to be two different species as they're now reproductively isolated:

• Temporal isolation: Species reproduce at different times
• Behavioural isolation: Species don't respond to each other's courtship behaviour
• Physical incompatibility: Size or shape of genitalss don't match 

When scientists propose things such as the development of new species, they must first gain support from other scientists to ensure that their work and findings are reliable and only then can it be published and accepted. Scientists can have their work:

• Dedicated to scientific journals for other scientists to read
• Peer reviewed to assess reliability and validity 
• Discussed at scientific conferences 

The following questions are usually considered while reviewing the work of other scientists:

• Is the scientific paper valid? Are conclusions based on good methods and are the data reliable?
• Is the paper signficant? It must be a useful addition to existing knowledge 
• is the paper original? Has somebody else already done the same work? 

The work can only be published if other scientists agree that the paper is all of the above things.