variation and evolution - speciation

Question 1

who was Alfred Russel Wallace? what did he do?

Answer 1

• a scientist
• travelled all over the world looking at different animals and plants. interested in warning colouration in animals. (bright red colour of frog thought to warn predators that frog is poisonous)
  he wanted to know how this had evolved

Question 2

what theory did Wallace propose?

Answer 2

the theory of evolution by natural selection.
Darwin and Wallace realised that had developed the same theory so jointly published findings

Question 3

how are new species formed?

Answer 3

speciation - Wallace came up with this

Question 4

What did Wallace notice leading to speciation?

Answer 4

• species were often separated by geographical barriers such as a wide river. since then for evidence for understanding of speciation

Question 5

How do new species form (speciation)?

Answer 5

• all species on one island can interbreed meaning any beneficial mutation spreads through whole population
• when species population separated there is no more interbreeding
• over time, natural selection will favour different alleles on the two sides of the island (for example, food sources could be different)
• due to no interbreeding, mutations that occur will not spread. this means over many generations, the 2 populations of species will begin to change
• if no more geographical barriers the 2 populations of species can mix again, but the phenotypes of the 2 populations are so different they can no longer interbreed to produce fertile offspring
• now 2 different species