Portal:Evolutionary biology

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Evolutionary biology

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Evolutionary biology is a sub-field of biology concerned with the origin and descent of species, as well as their change, multiplication, and diversity over time. Biologically, evolution is the change in the inherited traits of a population from generation to generation. These traits are the expression of genes that are copied and passed on to offspring during reproduction. Mutations in these genes can produce new or altered traits, resulting in heritable differences (genetic variation) between organisms. New traits can also come from transfer of genes between populations, as in migration, or between species, in horizontal gene transfer. Evolution occurs when these heritable differences become more common or rare in a population, either non-randomly through natural selection or randomly through genetic drift.
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The evolutionary history of life and origin of life are fields on ongoing geological and biological research. Although not necessary conditions for the acceptance of evolution by natural selection, the origin of life and its evolutionary history can nonetheless help shed light on evolutionary processes. The current scientific consensus is that the complex biochemistry that makes up life came from simpler chemical reactions, but it is unclear how this occurred. Not much is certain about the earliest developments in life, the structure of the first living things, or the identity and nature of any last universal common ancestor or ancestral gene pool. Consequently, there is no scientific consensus on how life began, but proposals include self-replicating molecules such as RNA, and the assembly of simple cells. The first simple, sea dwelling organic structures appeared about 3,400 million years ago. It is considered that they may have formed when certain chemical (organic) molecules joined together. Prokaryotes, single-celled micro-organisms like blue green algae, were able to photosynthesize and produce oxygen. Around thousand million years later, sufficient oxygen had built up in the atmosphere and hence it allow multicellular organisms to proliferate in the Precambrian seas.
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  • ...that adaptations enable living organisms to cope with environmental stresses and pressures?
  • ...that maintained gene flow between two populations can also lead to a combination of the two gene pools, reducing the genetic variation between the two groups?
  • ...that all forms of natural speciation have taken place over the course of evolution, though it still remains a subject of debate as to the relative importance of each mechanism in driving biodiversity?
  • ...that despite the relative rarity of suitable conditions for fossilization, approximately 250,000 fossil species are known?
  • ...that genetic sequence evidence thus allows inference and quantification of genetic relatedness between humans and other apes?
  • ...that the human species has a common ancestor with the ape? (similar to above reference)
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