This is natural selection in action. The advantageous color, green will increase in phenotype, and the brown beetles will decrease in phenotype. The genotype depends on whether or not one of the alleles is dominant. For example if the brown allele is dominant, then a heterozygote would be brown, but carry the green allele, which would not be expressed. But, eventually the brown allele would decrease in this population.Therefore, over time the genotypes would change favoring the green beetle due to natural selection.
1. Population of beetles: equal brown and green numbers in population
2. Natural habitat is in trees. Green leaves hide green beetles
3 The brown beetles are noticed by birds
4. Birds eat brown beetles
5. More green beetles survive than brown beetles
6. Green beetles reproduce in greater numbers
7. Beetle population changes from brown and green to mostly green beetles