My guess is that fat-soluble toxins that may occur in freshwater ecosystems would most affect apex species in these ecosystems. This is because fat-soluble toxins are stored in the fat reserves of animals, and then bioaccumulate up the food chain. So in this case, most of the toxin is not secreted, but stored within the food chain, and bioaccumulates, with the concentration becoming higher the further up the food chain.
The tilt of the Earth is what causes the seasons...In the summer, the northern pole is pointed closer to the Sun giving the northern hemisphere more daylight hours. The opposite is true during the winter.
Phylogenetic trees are often used to track what evolved from what.
Recessive<span> and </span>dominant alleles<span>. You will recall that genes have </span>different<span> forms called </span>alleles<span>. An </span>allele<span> can be </span>recessive<span> or </span>dominant<span>. A </span>recessive allele<span> only shows if the individual has two copies of the </span>recessive allele<span>.</span>
