Answer:
Darwin's theory of biological evolution tells us that all life on earth may have originated from a single, relatively simple reproducing creature living in the distant past. This idea is based on many observations, one of which is that when living things reproduce, children are often born with random new traits.
Explanation:
Answer:
If there wasn't a lot of organisms and energy in the productive part of the triangle, then there wouldn't be a lot of third level organisms. The energy piramid would be a lot smaller then what it is here, and maybe if the energy source was low then there might not be such a vast varity of animals in the ecosystem.
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In the early stages the embryos of four different species will look the same .For example, fish embryos and human embryos both have gill slits. In fish they develop into gills, but in humans they disappear before birth. That what makes them different.
