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biological species concept

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Biological Species Concept (BSC)

What are biological species? At first glance, this seems like an easy question to answer. Homo sapiens is a species, and so is Canis familaris (dog). Many species can be easily distinguished. When we turn to the technical literature on species, the nature of species becomes much less clear. Biologists offer a dozen definitions of the term "species". These definitions are not fringe accounts of species but prominent definitions in the current biological literature. Philosophers also disagree on the nature of species. Here the concern is the ontological status of species. Some philosophers believe that species are natural kinds. Others maintain that species are particulars or individuals. The concept of species plays an important role both in and outside of biology. Because of the important role of this concept, many biologists proposed definitions for this concept.
Over the last few decades, the Biological Species Concept (BSC) has become predominately the dominant species definition used in biology. This concept defines a species as a reproductive community. This though has had much refinement through the years. The earliest precursor to the concept is in Du Rietz (1930) then later Dobzhansky added to this definition in 1937. But even after this the definition was highly restrictive, the definition of a species that is accepted as the Biological Species Concept was founded by Ernst Mayr; “...groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups”. However, this is a definition on what happens in nature. Mayr later amended this definition to include an ecological component; “... a reproductive community of populations (reproductively isolated from others) that occupies a specific niche in nature. The BSC is greatly accepted among vertebrate zoologists and entomologists. Two reasons account for this addition to the definition of Biological Species Concept. Firstly, these are the groups that the authors of the BSC worked with (Mayr is an Ornithologist & Dobzhansky has worked mainly with Drosophila). More importantly, Sexual reproduction is the predominate form of reproduction in these groups. It is not coincidental that the BSC is less widely used amongst botanists. Terrestrial plants exhibit much greater diversity in their mode of reproduction than vertebrates and insects.
There have been many criticisms of the BSC in its theoretical validity and practical utility. For example, the application of the BSC to a number of groups is problematic because of interspecific hybridization between clearly delimited species.
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