The fossil record includes a progression from early biogenic graphite to microbial mat fossils to fossilised multicellular organisms. Īll life on Earth-including humanity-shares a last universal common ancestor (LUCA), which lived approximately 3.5–3.8 billion years ago. The processes that change DNA in a population include natural selection, genetic drift, mutation, and gene flow. In this synthesis the basis for heredity is in DNA molecules that pass information from generation to generation. In the early 20th century, competing ideas of evolution were refuted and evolution was combined with Mendelian inheritance and population genetics to give rise to modern evolutionary theory. In successive generations, members of a population are therefore more likely to be replaced by the offspring of parents with favourable characteristics for that environment. Evolution by natural selection is established by observable facts about living organisms: (1) more offspring are often produced than can possibly survive (2) traits vary among individuals with respect to their morphology, physiology, and behaviour (3) different traits confer different rates of survival and reproduction (differential fitness) and (4) traits can be passed from generation to generation ( heritability of fitness). The theory was first set out in detail in Darwin's book On the Origin of Species. The theory of evolution by natural selection was conceived independently by Charles Darwin and Alfred Russel Wallace in the mid-19th century as an explanation for why organisms are adapted to their physical and biological environments. The process of evolution has given rise to biodiversity at every level of biological organisation. Evolution occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, resulting in certain characteristics becoming more or less common within a population over successive generations. Evolution is the change in the heritable characteristics of biological populations over successive generations.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |