As of today’s date it has been very difficult to delineate the word species. Biologists have come up with dozens of definitions for the word species, but none have described the word species in a way that can define all living organisms, and how species should be defined or identified, and of course thatall biologists agreed (Agapow 2004 ; Bininda 2004 ; Crandall 2004; Gittleman 2004; Mace 2004; Marshall 2004; Purvis 2004). Moreover, the word “species” will be a very challenging word to explain with over twenty species concepts at present and the list keeps rising (Rieseberg 2001; Burke 2001). Out of these many species concepts at present, there are five that seemed very interesting; theBiological Species Concept, Recognition Species Concept, Ecological Species Concept, Phylogenetic Species Concept, and lastly the Evolutionary Species Concept.
One of the most popular species concepts is the Biological Species Concept (BSC). This concept refers to populations that cannot breed with different species. These species are reproductively isolated from others, therefore characterizingdistinct evolutionary lineages (Agapow 2004; Bininda 2004; Crandall 2004; Gittleman 2004; Mace 2004; Marshall 2004; Purvis 2004). The Biological Species Concept can clarify why species look very similar to one another, and how they differ from others. For example, when a male and a female horse breed, their genes will pass on to their offspring. As this process, it is repeated within the same species,genes from different horses and female horses are continuously shuffled in the species gene pool. The shared gene pool provides the species its identity. In conclusion, male and female horses’ genes stay in the same species so other species take on different appearance.
The Entomologist, Wilhelm Petersen, first originated the Recognition of Species Concept with the idea that a species is thebreed of its representation in evolution and its course. This concept was introduced by Hugh E. Paterson and it concerns the sexual ways established by the shared reproductive systems. Paterson’s ideas regarding the speciation, state that it is a consequence of the adaptation of bonding process to a new environment. This concept involves the specific mate recognition system. Each species recognize theopposite sex within that same species for possible mates (Lewin; 1981). A clear example would be American Crickets. Within the same habit, which in this case would be the United States, there are around 30 to 40 different species of crickets. Among the same species, the female cricket recognizes the song of a male and will only breed if that specific song is sung. This describes the materecognition system; it is a method of identification of those within the same species.
The Ecological Species Concept refers to species as a group of organisms or closely related organisms adapted to a specific set of resources, also known as a niche in the environment. The Ecological Species Concept leans more towards resources or niches, and zone adaptation rather than focusing on the isolatedreproduction (Boyd 5th ed; Silk 5th ed). Moreover, the Ecological Species Concept promotes the idea that natural selection plays an important role in generating and preserving species. An example of this concept would be the finches in the Galapagos Island with their different sized beaks. There are finches with large beaks and small beaks that satisfy their eating needs according to the seed size intheir different areas. If these two were to mate, a hybrid of a medium sized beak would be born and would fail to thrive. Therefore a medium beak finch population would have a short expected population density supporting the concept (Boyd 5th ed; Silk 5th ed).
The Phylogenetic Species Concept takes into account the evolutionary similarities between organisms and relies on mutual ancestry and shared...