What is macroevolution? How does it differ from microevolution? What evidence do we find in the fossil record that indicates macroevolution has occurred?
Macroevolution is the creation of new species, for example, reptiles from fishes or mammals from reptiles; but microevolution refers to adaptations to the environment that lead to differences within a certain species of organisms, e.g. different breeds of cats or dogs (Morris, n. d.). Furthermore, macroevolution happens over a long period of time, which can be millions of years, so its changes cannot be witnessed, while microevolution can be observed by people, for the reason that it can happen within a decade. Microevolution is horizontal and evolutionists believe that it leads to macroevolution, which is vertical (Morris, n. d.). Many scientists say that evolution has not occurred, since there is no fossil evidence. Nevertheless, in his article, Mark Isaak (2003) gives the definition of a transitional fossil, which is the following: “a transitional fossil is one that looks like it’s from an organism intermediate between two lineages, meaning it has some characteristics of lineage A, some characteristics of lineage B, and probably some characteristics part way between the two”, and he declares that there are many transitional fossils, for instance fossils of transitional forms from reptiles to mammals; according to him, that are many transitional fossils that prove evolution of apes to humans. In her article, Kathleen Hunt (1997) gives countless examples of transitional fossils, such as Cladoselache (from early fish to sharks), Hynerpeton (from fish to amphibians), Proterogyrinus (from amphibians to reptiles), Probelesodon (from reptiles to mammals), Archeopteryx (from mammals to birds), and a great number of other transitional fossils.
What is sexual selection and what role does it play in evolution? What are some of the strategies Darwin’s finches use in playing this role?
Sexual selection is a kind of natural selection that gives advantages in copulating. For example, certain males developed mutations that looked attractive to females, and so such males had better chances to copulate and give offspring, thus transmitting their mutations to their children (Andersson, 1994).
Sexual selection is, therefore, less rigorous than natural selection. Generally, the most vigorous males, those which are best fitted for their places in nature, will leave most progeny. But in many cases, victory depends not so much on general vigor, as on having special weapons, confined to the male sex. A hornless stag or spurless cock would have a poor chance of leaving numerous offspring (Darwin, 1859, p. 46).
So, sexual selection leads to preservation of those characteristics of phenotype that give males advantages in protecting their territories and fighting other males for food and females; accordingly, bigger, faster, stronger and brighter ornamented males will be chosen by females for copulating, and so they will transmit the genes responsible for their advantageous phenotypic characteristics to their offspring. However, sexual selection not necessarily preserved only life-saving mutations, often the mutations preserved by sexual selection did not give any advantages in survival, e.g. the peacock’s tail …