Parallelism in biology: examples and characteristics

There are three forms of evolution. Divergence is based on the similarity of homologous organs, convergence - of similar organs. The third form of evolution is parallelism.

In biology, this is a process in which development takes place associated with the acquisition of similar characteristics and qualities that develop independently and are based on homologous rudiments.

parallelism in biology

Parallel evolution and speciation

Parallel speciation is a typeparallel evolution in which the reproductive incompatibility of closely related populations is determined by features that develop independently due to adaptation in different environments. These groups of animals are reproductively incompatible, and only those populations that live in similar ecological conditions are less likely to become reproductively isolated.

parallelism in biology

The form of evolution

Parallelism in biology describes how independentvarieties acquire similar characteristics due to their evolution in similar ecosystems, but not at the same time (eg, dorsal fins of sharks, cetaceans and ichthyosaurs). The definition of a characteristic is crucial in determining whether a change is considered divergent, convergent or parallel.

Proceeding from this, parallelism in biology is the development of a similar trait in related but separate species having the same common ancestor.

parallelism in biology is

Accounting for the homology of morphological structures

It is also necessary to take into account the homology of the morphologicalstructures. For example, many insects have two pairs of flying wings. But in beetles the first pair of wings hardens into the elytra, while the second pair is used in flight, while in flies the second pair of wings is reduced to small nedouzles used for balance.

If two pairs of wings are consideredinterchangeable, homologous structures, this can be characterized as a parallel reduction in the number of wings, but otherwise the two changes occur with different discrepancies in one pair of wings.

parallelism in biology characteristic and examples

Parallelism in biology: characteristics and examples

An example of parallelism is the similarity of the axialskeleton ichthyosaurus and dolphin. For this form of evolution, the appearance of similar characteristics or adaptive mechanisms in non-related organisms is characteristic due to the nature of their environment.

Or, in other words, parallelism in biologyis observed under similar conditions, the result of which is the formation of such adaptations. Morphologies (or structural forms) of two or more lines develop together in a similar way in parallel evolution, rather than diverge (as in convergence) or do not converge (as in divergence) at a particular time.

parallelism in biology

One of the examples are complexes of models of feathering, which developed independently in different species of birds. You can name and other examples:

  • In the plant kingdom, the most familiar patterns of parallel evolution are similar leaf shapes, which again and again appear in separate genera and families.
  • Butterflies have much in common in wings color models both within one species, and among families.
  • Ancient and modern porcupines share a commonancestor, both developed strikingly similar body structures. This is also an example of convergent evolution, as similar structures evolved in the hedgehog and echidna.
  • Some extinct arhosaurs developed an upright posture and were probably warm-blooded. These two characteristics also occur in most mammals.
  • It is interesting that modern crocodiles have a four-chambered heart and an additional, the so-called left artery, which is also characteristic of the Trian mammals.
  • In extinct pterosaurs and birds, both wings were developed, as well as the beak, but not from a common ancestor.
  • Internal insemination independently developed in sharks, some amphibians and amniotes.

parallelism in biology

There are, incidentally, and quite unusual examplesparallelism in biology. So, the eye of the octopus has the same complex structure as the human eye. This is quite unusual, because two species developed at a time when animals were turning into vertebrates and invertebrates.

Parallelism in biology is an appearance in evolutionliving beings of similar characteristics and properties, which are formed from the same primordia and on a single genetic basis, but this occurs independently of each other.

parallelism in biology

The main difference from convergence

But this form should be distinguished from convergence- when similar signs appear also independently, but the genetic basis for their appearance is different. Both there and there are common features in the structure of the body, but the species of animals are different at the same time.

Translated from Greek, parallelos means"side by side". Parallelism in biology is an evolutionary development of genetically close groups on the basis of features that they inherited from common ancestors. Certain similar features and properties in parallelism allow us to point out the unity of origin of these living organisms, and also the existence of similar conditions and habitats.

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