Biological Species Concept

We can start the biological species concept by introducing three prominent species concepts. Though there are many more prominent concepts of species, introducing only three will be sufficient. The species concept which is the most common in biology literature is Mayr’s (1970) biological species concept. 

The ecological species concept defines that particular species taxon as the ancestry of organisms that is maintained by all ecological forces (Van Valen, 1976) and also segmented by the same. According to the biological species concept meaning, ‘ a species ‘ rectitude is maintained by a mode of reproduction (interbreeding) within the same species and also by reproductive barriers between organisms in different species. The species concept which has multiple versions known as Phylogenetic defines a species taxon as a basal monophyletic lineage [Mishler and Brandon, 1987. 

Reproductive community

The members of the biological species concept form a group or a reproductive community and seek a partner within the group. This community is formed for reproduction; all the individuals of the species see or recognize each other as potential mates. Under the biological species concept, species are more or less simultaneously a reproductive community, a gene pool also a genetic system. The study of reproductive isolation mechanisms is central to the biological species concept because these mechanisms act as a barrier to gene flow that defines the perimeter of the reproductive community and gene pool, and preserves the integrity of the genetic system.

However, in practice, isolating mechanisms are seldom studied and the species are usually diagnosed by differences in phenotypic or morphological features. For obvious reasons, the asexual taxa are excluded from this concept, but it should be also known that many species which are capable of sexual reproduction cannot be easily summoned within the framework of the biological species concept. The gene exchange between these species which is limited, or prevented by reproductive isolating mechanisms includes species-specific breeding behaviors, hybrid sterility, and gametic incompatibility.

Ecological unit

The species members of the ecological unit differ from each other due to various allocations, but all the members together form a cooperative unit. They are capable of interacting with other species in any environment as a unit. We can conclude the definition of the ecological species concept as a species taxon as parentage of organisms maintained and also segmented by ecological forces (Van Valen, 1976). A stabilized selection maintains species integrity, while disorderly selection can lead to new species. 

All three species concepts, the biological concept, the ecological concept, and the phylogenetic concept not only provide various definitions of ‘species’ even there is a rise to different classifications of the organic world by their use. 

For the ecological unit of the species concept, the species are defined genealogically, not dependent on any mode of reproduction. In the ecological unit of the biological species concept, this informs about a concept of species or a set of various organisms adapted and evolved to a particular set of resources, known as a niche in this particular environment. According to this concept of niche, populations form distinct phenetic groups that we recognize as species because the ecological and evolutionary processes control how the resources will be divided to tend to produce the clusters.  

Genetical unit

Genetic variation is known as the type of variation that refers to the differences among the genomes of members of the identical species. All the hereditary information from all the genes of an organism is known as the genome. Genes are known as units of hereditary information as they carry around the information or instructions for building proteins. 

These proteins are encoded with the genes which enable them to function. Usually, two copies of each gene are present in organisms that reproduce sexually because each parent cells or organisms donate genes, each copy of genes are donated by each parent to their offspring’s. Genes also exist in slightly different forms known as alleles, which are further added to the genetic variation.

The product formed by the combination of alleles of a gene that is received to each individual from both parents determines what biologists refer to as the genotype of a particular trait ( for example – the hair texture of a new offspring ). The genotype possessed for a trait that an Individual, in turn, determines the phenotype (the set of characteristics that are observable in an individual formed from the interaction of its genotype with the environment).  

The observable characteristics include hair texture, such as whether an individual is given up with straight, wavy, or curly hair. A species can result from a few different sources because of genetic variation within a species. The following labeled biological species concept diagram explains the rest part.