Answer:
disturbance has destroyed population in a community
Explanation:
The secondary succession occurs after there has been some disturbance that has manged to badly damage or destroy the populations in a community. This basically means that after some catastrophic event that happened to a certain population or populations, other species moved in to colonize the freed space. There are countless examples of secondary succession in nature, and one of the best is when there is a strong volcanic eruption. The volcano manages to destroy the population of plants and animals in its close surroundings, but after the eruption ends, the space starts to be colonized by new plants and animals step by step until they create a new well functioning community.
Answer:
The return of blood to the heart is assisted by the action of the skeletal- muscle pump. As muscles move, they squeeze the veins running through them. Veins contain a series of one-way valves, and they are squeezed, blood is pushed through the valves, which then close to prevent backflow.
Cat (Australia); lots of cats became feral and they reproduce very fast. They became the apex predator and the native species have no defense system for them, so the cats brought tens of species on the verge of extinction (mainly placental mammals).
Fox (Australia); became an apex predator in the lack of competition, and damages the populations of native small placental mammals.
Hair (Australia); reproduces much quicker than the native species of mammals, increased significantly in numbers, and out competes the native species for the food sources.
African bee (the Americas); much more aggressive and stronger than the native bees and systematically kills their populations.
Grey squirrel (Britain); reproduces quicker than the red squirrel, is bigger, and out competes for food, brought it on the verge of extinction.
