Evolution is the process by which changes or transformations occur in living beings over time, giving rise to new species.
Evolution has its bases strongly corroborated by the comparative study of organisms, whether fossil or current. The most important topics of this study will be briefly presented.
Homology and Analogy
Per homology similarity between structures of different organisms is understood to be due solely to the same embryological origin. The homologous structures may or may not perform the same function.
The man's arm, the horse's paw, the bat's wing and the whale's fin are homologous structures to each other, since they all have the same embryological origin.
In such cases, there is no functional similarity. However, when analyzing the bat wing and the bird wing, it appears that both have the same embryological origin and are still associated with the same function.
The homology between structures of 2 different organisms suggests that they originated from a common ancestral group, although it does not indicate a common degree of closeness, departing from several evolutionary lines that originated from several different species. irradiation adapted.
Homology: embryological origin of structures of different organisms, and these structures may or may not have the same function. The homologous structures suggest common ancestry.
Analogy: refers to the morphological similarity between structures, as a function of adaptation to the execution of the same function. The wings of insects and birds are different structures in embryological origin, but both are adapted to perform the same function: flight. They are therefore analogous structures.
The analogous structures do not in themselves reflect any degree of kinship. They provide evidence of the adaptation of structures of different organisms to the same ecological variable. When non-closely related organisms have similar structures performing the same function, we say that they suffered convergent evolution.
Unlike the adaptive irradiation (characterized by the differentiation of organisms from a common ancestor giving rise to several different groups adapted to explore different environments) convergent evolution or evolutionary convergence It is characterized by the adaptation of different organisms to an equal ecological condition, so the body shapes of the dolphin, fish, especially sharks, and a fossil reptile called ichthyosaur are quite similar, adapted to swimming. In this case, the resemblance is not a sign of kinship, but a result of their adaptation to the aquatic environment.