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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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A drone fly exhibits Batesian mimicry by resembling a honey bee
In evolutionary ecology, mimicry describes a situation where one organism, the mimic, has evolved to share common outward characteristics with another organism, the model, through the selective action of a signal-receiver or "dupe". Collectively this is known as a mimicry complex. The model is usually another species except in cases of automimicry. The signal-receiver is typically another intermediate organism, e.g the common predator of two species, but may actually be the model itself (such as an orchid resembling a female wasp). As an interaction, mimicry is in most cases advantageous to the mimic and harmful to the receiver, but may increase, reduce or have no effect on the fitness of the model depending on the situation. Models themselves are difficult to define in some cases, for example eye spots may not bear resemblance to any specific organism's eyes, and camouflage often cannot be attributed to any particular model. Camouflage, in which a species appears similar to its surroundings, is essentially a form of visual mimicry, but usually is restricted to cases where the model is non-living or abiotic. In between camouflage and mimicry is mimesis, in which the mimic takes on the properties of a specific object or organism, but one to which the dupe is indifferent. The lack of a true distinction between the two phenomena can be seen in animals that resemble twigs, bark, leaves or flowers, in that they are often classified as camouflaged (a plant constitutes its "surroundings"), but are sometimes classified as mimics (a plant is also an organism). Crypsis is a broader concept that encompasses all forms of detection evasion, such as mimicry, camouflage, hiding etc.
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Dusky Seaside Sparrow
Credit: Splintercellguy

Orange Band, the last Dusky Seaside Sparrow died in 1987 in a captive facility in the Walt Disney World Resort

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Did you know...

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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 Charles Darwin's theory of evolution is under attack by respected scientists like evolutionary biologist Stuart Newman.
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