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Biologists most often define biodiversity as the "totality of genes, species and ecosystems of a region". [8] [9] An advantage of this definition is that it presents a unified view of the traditional types of biological variety previously identified: taxonomic diversity (usually measured at the species diversity level) [10]
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]
Possible global glaciation [56] [57] which increased the atmospheric oxygen and decreased carbon dioxide, and was either caused by land plant evolution [58] or resulted in it. [59] Opinion is divided on whether it increased or decreased biodiversity or the rate of evolution. [60] [61] [62] 600 Ma
Coextinction can extend beyond biodiversity and has direct and indirect consequences on the communities of lost species. One main consequence of coextinction that goes beyond biodiversity is mutualism, by loss of food production with a decline in threatened pollinators. Losses of parasites can have negative impacts on humans or the species.
The result of four billion years of evolution is the diversity of life around us, with an estimated 1.75 million different species in existence today. [ 71 ] [ 72 ] Usually the process of speciation is slow, occurring over very long time spans; thus direct observations within human life-spans are rare.
Mosaic evolution – Evolution of characters at various rates both within and between species; Parallel evolution – Similar evolution in distinct species; Quantum evolution – Evolution where transitional forms are particularly unstable and do not last long; Recurrent evolution – The repeated evolution of a particular character
Biogeography is a synthetic science, related to geography, biology, soil science, geology, climatology, ecology and evolution. Some fundamental concepts in biogeography include: allopatric speciation – the splitting of a species by evolution of geographically isolated populations; evolution – change in genetic composition of a population
Darwin's finches. Evolutionary biology is the subfield of biology that studies the evolutionary processes (natural selection, common descent, speciation) that produced the diversity of life on Earth.