Portal:Evolutionary biology

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The Evolutionary Biology Portal

Introduction

Evolutionary biology is the subfield of biology that studies the evolutionary processes that produced the diversity of life on Earth, starting from a single common ancestor. These processes include natural selection, common descent, and speciation.

The discipline emerged through what Julian Huxley called the modern synthesis (of the 1930s) of understanding from several previously unrelated fields of biological research, including genetics, ecology, systematics and paleontology.

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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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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?

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