Answer:
competition
Explanation:
After an ecosystem has been destroyed because of certain catastrophe and all of the space that it occupied is totally cleared and open for overtaking, the primary succession comes in action. When the primary succession occurs, there's no competition, as pretty much everything has been destroyed from the previously existing ecosystem. The pioneers of the primary succession are organisms that do not require a lot to prosper, such as the mosses and lichens. As they start to cover the barren land, little by little they manage to change the composition of the rocks, thus resulting in the formation of the first soils. As that happens, the secondary succession comes on the horizon as now it has conditions for it, so the species from it overtake and replace the species form the primary succession.
The right answer is CaF2
Calcium fluoride is an inorganic compound of formula CaF2. This ionic compound consisting of calcium and fluorine is naturally present in nature in the form of fluorine (also known as fluorite). It is the world's leading source of fluoride.
It is a solid insoluble in water, whose structure is cubic where each atom of calcium is adjacent to eight atoms of fluorine, and each atom of fluorine to four atoms of calcium.
Population size and density is calculated by using a variety of field sampling methods, including quadrats and mark-recapture.
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Answer:
It is true that studying natural selection in the fields can be challenging. Some of the challenges which Darwin might have faced could have been:
Darwin was only studying one trait for his results. But there might have been many other factors or traits affecting natural selection.
Natural selection does not happen rapidly hence Darwin would have had to wait for many generations to observe the results.
The environment is not such an easy factor to study. It is complex. It might have happened that the environment might have changed before any changes were seen in the population of the birds.
