This is unusual because invasive species with greater genetic diversity often have a greater chance at survival — a more diverse
gene pool means more variety in traits of individuals for natural selection to act
upon and allow the species to survive and thrive in a new area.
However, with only a small
gene pool to draw
upon, a genetic bottleneck was created, potentially causing the present - day problems of congenital defects such as cleft palates, spinal deformities and heart, brain and eye deformities.