Answer:
At almost the opposite point on the Earth's surface, the "P" waves reappear. The shadow zone exists because the waves are refracted as they pass through the boundary between the mantle and the core and are diverted from their original paths.
Geological change will not cause a mass extinction, because it happens on a too big scale - on the scale of millions of years. During such long time, it is more likely that other causes will influence the survival of extinction of species, such as climate change or environmental disasters, and even if there is a small influence, it would not be significant next to other causes.
It has something to do with finding the aftershocks of 3 locations around it.
Answer:
In species with polyploid, there are more chromosomal sets than in diploid one. Becouse there are more chromosomal structures available, events like mutation, recombination, DNA lose, are more probable to occur.
As the generations pass, the accumulation of these changes tend polyploid to speciation.
