I would say immigration only.
emigration would theoretically reduce the genetic variation as unique individuals leave, but immigration would bring unique traits into circulation in an ecosystem.
I'm not super great at biogy tho so this might not be right... :)
“This transient switch in membrane potential is the action potential. The cycle of depolarization and repolarization is extremely rapid, taking only about 2 milliseconds (0.002 seconds) and thus allows neurons to fire action potentials in rapid bursts, a common feature in neuronal communication.”
This question dose not have enough info to answer, i'll gladly help if this question had a date in which mercury was used or what had mercury in it.
I apologize.
Answer:
It could require the removal of massive amounts of top soil, leading to erosion, loss of habitat and pollution.
Explanation:
Coal mining causes acid mine drainage, which causes heavy metals to dissolve and seep into ground and surface water.
Both a b c are the right answer choice for this question