Relier Pairs Origin and evolution of lifeVersion en ligne Theories of evolution par Isabel Pérez Cotorruelo 1 Darwinism 2 Endosimbiosis theory 3 Puntuated equilibrium 4 Evolutionary development biology 5 Fixism 6 Neo-darwinism 7 Neutralism 8 Lamarckism Most mutations are neither benefitial nor harmful for the individuals that have them, so natural selection does not affect them. Some genes act as switches for other gene groups during embrionic development. Individuals of a species that have more favourable characteristics survive more. Eukariotic cells originated as a result of two different types of bacteria joining together. The necessity creates the organ. The acquired characteristics are transmitted to offsrping. The reasons behind the variation within a species are mutations, genetic recombination and sexual reproduction. The evolutionary process does not always take place in a slow gradual way. Instead in many cases new species are form rapidly. Living things do not change, species always stay the same
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