Speciation And Evolution: Definition and Examples

Speciation is the process through which new species come from existing ones, playing a crucial role in evolution. It occurs due to factors like geographic isolation, genetic variations, and natural selection. Speciation drives biodiversity and explains the relationships between organisms. In this article, speciation and evolution, modes of speciation, mechanisms of evolution, and factors affecting speciation and evolution are discussed. Speciation and Evolution is a topic of the chapter Evolution in Biology.

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1. Definition of Speciation and Evolution
2. Modes of Speciation
3. Mechanisms of Evolution
4. Factors Affecting Speciation and Evolution

Definition of Speciation and Evolution

Speciation can be defined as the process whereby some new distinct species are formed from other already existing species due to mechanisms that cause genetic differences as well as a lack of compatibility in reproduction. While, on the other hand, the process of evolution is defined as the alteration in the heritable characteristics of biological populations during successive generations influenced by factors like natural selection, mutation, gene flow, and genetic drift.

Combining concepts like speciation and evolution gives a complete and elaborate perspective to the understanding of the differences in the forms of lives and their survival mechanisms in various ecosystems comprehensively identified as the ever-changing face of the Earth’s biodiversity.

Modes of Speciation

The types of speciation are described below-

Allopatric Speciation

Allopatric speciation takes place when physical barriers separate different populations of a species hence separating them genetically to warrant new species.

Sympatric Speciation

Sympatric is the process which occurs with no geographical isolation so it occurs through factors such as polyploidy in plants or different habits due to behaviour in the same geographical area.

Peripatric Speciation

It entails the splitting of a small population from a large one and often accompanies a process such as genetic drift and founder effect that explain how new species arise.

Parapatric Speciation

Thus, parapatric speciation is a process when populations are somehow isolated but have some contact along certain lines.

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Mechanisms of Evolution

The mechanism is described below-

Natural Selection

Natural selection says that if certain favourable characteristics were to be liked, then the possessor of such characteristics is likely to leave behind progeny which has similar characteristics. They include for instance; the formation of antibiotic resistance in bacteria and the evolution of Darwin’s finches feeding habits.

Genetic Drift

This means that genetic drift refers to the probability of changes in allele frequencies within the context of a gene pool, which is most effective in small populations. Genetic drift is well illustrated by the events such as the bottleneck effect which refers to the reduction of population size and the founder effect which involves the establishment of a new population by a few individuals.

Gene Flow

Migration is the interchange or exchange of genes between populations and it leads to the introduction of certain factors that reduce the degree of dissimilarity between two populations.

Mutation

Mutations, therefore, can be regarded as the primary source of variation, beneficial or deleterious, in the known hereditary material sequence.

Factors Affecting Speciation and Evolution

The factors are described below-

Geographic Isolation

Geographical isolation, for example by mountains, rivers and seas isolates populations and does not allow them to interbreed – which leads to the formation of a new species.

Case Study: The isolation of finch populations by being on different islands yet all parts of the Galapagos led to Darwin’s Finches owing to their different adapted beaks to feed from separate trees.

Reproductive Isolation

Structures that ensure different species do not mate with one another. Some of the prezygotic barriers include temporal, which refers to species that only mate at different seasons, while behavioural, mechanical and gametic refer s to species whose reproductive behaviours, structural attributes and sperm respectively are incompatible. Postzygotic barriers consist of reduced hybrid viability; offspring die in the process of their development, or hybrid sterility, and offspring cannot reproduce.

Ecological Factors

One of the speciation mechanisms involves differences in ecological roles that populations occupy in a community. Example: Different species of cichlid fish are endemic to the African great lakes and these come in different forms and behaviours that are in line with their specific productive roles in the given environment.

Genetic Factors

Chromosomal variations and polyploidy thus cause reproductive isolation and, therefore, promote the process of speciation. Other reasons for isolation arise from studying genetic distances due to the accumulated mutations, in the ability to reproduce with a different population successfully.

Environmental Changes

Environmental shocks, which include climate change and habitat destruction, can introduce new selective forces in a species’ population and affect evolution. These changes can lead to For example, if one difference is that students have more free time than in the past, then one implication of that difference is that students are being proactive in their learning by seeking out knowledge.

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