The question is incomplete as it does not have the options which are:
A. Speciation
B. the founder effect
C. natural selection
D. gene flow
Answer:
Founder effect
Step-by-step explanation:
The founder effect is the phenomenon observed when the members of the population establish a new population.
This effect is observed due to the immigration and emigration of the individuals of the population.
In the given question, the four lizards swept away with the ocean and reached a new island. There they reproduced and flourished and by the time they formed the new population with orange stripes. This is the case of the genetic drift especially the founder effect in which the new alleles for the orange tail expressed.
Thus, the founder effect is the correct answer.