Answer :
The bottleneck effect occurs when the majority of a population is destroyed due to natural disasters or human activity's. This reduces the size of the gene pool resulting in smaller variations from bird to bird. Gene mutation is the permanent change in the DNA or gene. Stabilizing selection occurs when genetic diversity decreases and the majority of the population stabilizes on a specific trait. The Founder effect occurs due to a smaller population leaving a larger population. This leaves the smaller population with smaller genetic variations. The correct answer is the Founder effect.