The Cohesion Species Concept (CSC) is a biological framework that defines species in terms of the cohesive mechanisms that maintain their integrity and distinctiveness. Developed by biologist David J. Futuyma and others, the CSC emphasizes the role of gene flow, genetic cohesion, and shared evolutionary history in delineating species boundaries.
Key features of the Cohesion Species Concept include:
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Genetic Cohesion: Species are characterized by a high degree of genetic similarity and interbreeding among their members, which contributes to a shared gene pool. This cohesion arises from various factors, including reproductive isolation mechanisms that prevent gene flow with other species.
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Adaptive variation: Within a species, local adaptations may occur, but these do not compromise the overall cohesiveness of the species. The concept highlights that species are not monolithic; they can have variations and subspecies but remain genetically connected.
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Evolutionary Processes: The CSC acknowledges that species are dynamic entities affected by evolutionary processes. It considers how evolutionary forces, such as natural selection and genetic drift, shape the cohesion of a species over time.
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Reproductive Isolation: The CSC integrates aspects of reproductive isolation, which is crucial for maintaining distinct species. This can be postzygotic (affecting the viability of hybrid offspring) or prezygotic (affecting mating behaviors or timing).
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Focus on the Cohesive Nature: Rather than solely relying on morphological characteristics or ecological niches, the CSC focuses on the cohesive forces that unify individuals into a species.
In summary, the Cohesion Species Concept provides a holistic view of species as groups of interbreeding populations that are evolutionarily distinct, emphasizing the genetic and ecological connections that promote cohesion within species while allowing for diversity and adaptation.