<h3><u>Answer;</u></h3>
A. global temperatures drop several degrees after several massive volcanic eruptions
<h3><u>Explanation;</u></h3>
- <em><u>A mass extinction refers to a widespread and a rapid decrease in the Earth's biodiversity. </u></em>
- <em><u>Mass extinctions may occur due to a number of reasons which includes, asteroid impacts, climate change, massive volcanic eruptions or a combination of all these causes. </u></em>
- <em><u>An example of mass extinction was during the Mesozoic Era, that led to the extinction of dinosaurs, about 65 million years ago.</u></em>
Answer:
b. It is evolution above the species level.
Explanation:
Macroevolution is the evolution that generates new taxa, for examples two or more species from a common ancestor. Macroevolution is the product of microevolutionary processes, it is, of <u>microevolution</u>: the change in allele frequencies in a population over time. Macroevolutive changes are commonly evident while not all microevlutive changes are not.
The best evidence of such phenomena could be a population's genetic variation decrease.
When a population bottleneck occur it means that for some reason (i.e. environmental events) the size of a population is largely reduced. This leads to reduction of the genetic variation in that new smaller population. When a bottleneck occur, the founder effect is normally seen, which is that one population is established by a small group of a previously larger population leading once again the genetic variation, now though with a bigger population, to be very reduced.
B. only 3% of water on earth is fresh
