Atoms > Molecules > Organelles > Cells > Tissue > Organ > Organ System > Organism
Answer:
Because earthworms do not like soil that is too acid, alkaline, dry, wet, hot or cold, their presence is a good indicator of soil conditions suitable for plant growth. Earthworms do not like acid soils with pH (CaCl2) less than 4.5. The addition of lime raises pH and also adds calcium.
I'm not entirely sure and this response is late but I'm pretty sure it's when the central vacuoles lose their water and can no longer support the cell. When the vacuole of a cell is full it pushes outward against the cell wall. When it has nothing in it, you can assume that because the vacuole is so big and is such a big component of this that this would be the answer.
Answer;
A bottleneck effect
Explanation;
When only a few individuals survive unfavorable times, thereby losing the majority of genotypes in the next generation, it is called a bottleneck effect.
It occurs when there is a disaster of some sort that reduces a population to a small handful, which rarely represents the actual genetic makeup of the initial population.
The fossils from prehistoric organisms can be compared to present day organisms showing the differences in how much thwy have changed.