Population has a small size, high level of genetic drift and very little migration into the population. What will most likely happen to the genetic diversity of the population over time?

The difference between causal and correlational relationships is as following:

A correlational relationship is defined as a measure of relationship between two variables and the variables can be negatively correlated, positively corelated or not correlated at all.

Relation between two events said to be causal relation, if the occurrence of the first causes the other. It means the effect of second event should be caused by the the first event.

So, causal relationship between two variables must be correlated.

For example: there is a positive correlation between the organisational behaviour and work done. if any one employee will deny to work from the group of 4 employees it will affect other employees behaviour and reduces their working ability, which will reduce tehir work done. It means that organisational behaviour between employees is the cause of less work done. so, the second event (work done) is the cause of first event (organisational behaviour) and they both are positively correlated as well.