<span>Parents can pass on chromosomes to their children that are different than their own when the new gene combinations are created by crossing over. The exchange of genetic material between homologous chromosomes is known as crossing over which occurs in meiosis. When homologous chromosomes pair up and exchange different segments of the genetic material. As the result, a new combination of genes will be formed. If there was not crossing over, all genes on a chromosome would be inherited together.</span>
Well If the Salmon die from lack of food from polution or something, and other animals benafit from the nutrience they carry. the rest of the ecosystem might parish, i hope that helped im not sure what was wanted
