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Evolution is the change in the heritable characteristics of biological populations over successive generations. [1] [2] It 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. [3]
Inheritance of acquired characteristics was part of Haeckel's recapitulation theory of evolution, which held that the embryological development of an organism repeats its evolutionary history. [ 111 ] [ 112 ] Critics of neo-Lamarckism, such as the German biologist August Weismann and Alfred Russel Wallace, pointed out that no one had ever ...
Some examples of evolution in species over many generations are the peppered moth and flightless birds. In the 1930s, the discipline of evolutionary biology emerged through what Julian Huxley called the modern synthesis of understanding, from previously unrelated fields of biological research, such as genetics and ecology, systematics , and ...
Convergent evolution – Independent evolution of similar features List of examples of convergent evolution – Examples of separate lineages of organisms developing similar characteristics; Divergent evolution – Accumulation of differences between closely related species populations, leading to speciation
The key to life history theory is that there are limited resources available, and focusing on only a few life history characteristics is necessary. Examples of some major life history characteristics include: Age at first reproductive event; Reproductive lifespan and ageing; Number and size of offspring
These theories often combined orthogenesis with other supposed mechanisms. For example, Eimer believed in Lamarckian evolution, but felt that internal laws of growth determined which characteristics would be acquired and would guide the long-term direction of evolution. [41] [42]
In biology, evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organization , from kingdoms to species , and individual organisms and molecules , such as DNA and proteins .
Professor of biology Jerry Coyne sums up biological evolution succinctly: [3]. Life on Earth evolved gradually beginning with one primitive species – perhaps a self-replicating molecule – that lived more than 3.5 billion years ago; it then branched out over time, throwing off many new and diverse species; and the mechanism for most (but not all) of evolutionary change is natural selection.