Use this example to describe how natural selection led to the process of speciation that - The original species of anole lizards was separated - into different populations - by a geographical barrier — which is the sea - There was no gene flow - between the separated populations - Each population was exposed to different environmental conditions - on each island - Because there is variation among the lizards - Natural selection occurred independently in each population - Some had favourable characteristics to survive on a specific island - while others did not - The ones that did not have the favourable characteristics died - The ones with the favourable characteristic survived - and reproduced - to pass the gene for the favourable characteristics - to the next generation - And over many generations the favourable characteristic becomes more frequent - and each population became different from the other over time - genetically - and phenotypically - If they would not be able to reproduce/interbreed with each other. - NSC Life Sciences - Question 4 - 2017 - Paper 2

Separation of the Original Species: The original species of anole lizards was separated by a geographical barrier, specifically the sea. This separation led to different populations of lizards.

Isolation and Lack of Gene Flow: Due to the geographical barrier, there was no gene flow between these isolated populations. Each population thus developed independently.

Different Environmental Conditions: Each population was exposed to different environmental conditions on the islands. This variation in the environment played a crucial role in natural selection.

Variation among Lizards: There is inherent variation among the lizard populations. Some individuals possessed characteristics favorable for survival in their specific environments while others did not.

Independent Natural Selection: Natural selection occurred independently in each population. Those individuals with favorable traits survived and reproduced, while those without such traits perished.

Reproduction and Gene Sharing: The lizards that survived passed on their favorable characteristics to the next generation, thereby giving them an advantage in future generations.

Increased Frequency of Favorable Characteristics: Over many generations, the traits that were favorable became more common among the lizards within each population.

Genetic Divergence: Over time, each population developed different genetic traits, becoming distinct from one another due to the unique selective pressures in their respective environments.

Phenotypic Differences: Alongside genetic changes, phenotypic differences emerged as a result of the different survival needs imposed by their environments. This divergence eventually resulted in speciation as they could no longer interbreed, even if they were to come into contact again.