The Question of Species: An Argument

The question has been asked time and time again, “What is a species?” In response to the question, many have sought out the answer through research and analysis. Of species, Darwin once wrote to Joseph Hooker:

It is really laughable to see what different ideas are prominent in various naturalists' minds when they speak of species; in some, resemblance is everything and descent of little weight - in some, resemblance seems to go for nothing, and Creation the reigning idea - In some, descent is the key, - in some, sterility an unfailing test, with others it is not worth a farthing. It all comes, I believe, from trying to define the indefinable. (Letter from Darwin to Hooker, 24 December 1856; Darwin 1887, p. 88).

In a later letter to Hooker, he explained, “How painfully true is your remark that no one has hardly the right to examine the question of species that has not minutely described many.” (Darwin 1987, 253) Darwin’s comments are very true. Unless one has done in depth studies on the subject of species, one can, in no way, be an authority on the subject. Considering that there are definitely different theories of evolution, just as there are many different theories on one’s definition of species, it is necessary to review some of these different theories. If one believes in the morphological species definition, as Darwin mentioned above, a species would have several visible features that are unique to their own respective group. If one believes in the evolutionary concept of species, “a species descends from a common ancestor and shared evolution.” (What is a Species) The biological species definition would be a belief that only those who interbreed within their own groups in a natural setting isolated from other species would be considered a species. Any asexual organisms would not be considered a species. Select fish or animals that breed in captivity or a controlled environment like an aquarium would not be considered species. Another species definition is the genotypic cluster definition. A species is a group of organisms or beings that share a common genetic makeup. Those who are genetically different are grouped into different respective groups. In response to how this speciation occurred, there are two choices, punctuated equilibrium and phyletic gradualism. The punctuated equilibrium theory is a sudden initiation of a species through radical mutation in the early development stage and are “reproductively isolated from the parent species.”(Teed, 1998) Phyletic gradualism, is the process of speciation which evolves as “beneficial mutations once in a while and spread through the population.” (Teed, 1998) This gradually changes the species over time and within the group a new speciation model has emerged. It is like a growing bush with new branches that form. “The human lineage emerged as a branch, while the rest of the trunk continued as apes.” (VanDeVeer, Pierce, 494) It is this author’s conclusion that the genotypic cluster definition is the most accurate description and definition of a species, and that these different species have evolved through phyletic gradualism.

As mentioned above, it is the author’s opinion that the genotypic cluster concept is the correct description by which species can be defined. The genotypic cluster definition is by far the newest definition and is based upon genetic differences found in various species. These findings come after years of research and testing in the field of taxonomy. Modern advances in technology and the use of DNA clusters helped to pinpoint and properly identify different species and subspecies. In studying this concept, one can see the thought behind the theory, and it makes good sense. It means that DNA clusters are arranged differently within different organisms. Whether these differences are slight or great, it aids scientists (taxonomists) in placing species into their different groups and subgroups. Using the example of a domestic dog and a coyote, they have a similar appearance outwardly, yet a small difference in their genetic clusters brings out differences in habits, location, vocal communications, and even slightly in looks. Yet through their genetic differences, they are placed in the same species (canis), but a different subspecies group. Whether these two subspecies were the same at one time or not is unknown for certain, but the theory is, that they were the same at one time and through a gradual evolution process, probably through interbreeding and regional reproductive isolation, they divided into separate subgroups. The facts in favor of the definition of species using the genotypic cluster concept have been proven to be very effective. DNA is something that has been studied in great detail by geneticists both in the past and even today and have been proven to be very reliable in identification, so the author feels very confident in endorsing the genotypic cluster definition of species.

The genotypic cluster definition of species is criticized the least by opponents in today’s world, however there are those who have points to make in favor of their own definitions. Those who endorsed the morphological definition of species feel they are justified in their belief that everything should be classified through their typological appearance. This way of thinking, “had traditionally been the decisive criterion of species.” (Mayr) However, it has been shown that there were “many good biological species that do not differ at all morphologically or only very slightly.” (Mayr) These species were called sibling species. They are morphologically alike, yet they were genetically different. There was also proof later that there were many in the same species who were morphologically different. Even in its day, there were those who “in their writings, foreshadowed a different species concept…” from the morphological concept. (Mayr)

Two writers, in particular, Darwin and Buffon adopted the concept of biological species, wherein species have to be reproductively isolated from each other in order to be considered a separate species. This is problematic, however, because those who adopt this theory place certain organisms that are slightly different into the same group, because they assume that these different organisms would probably end up interbreeding anyway. Also, as I stated earlier, the offspring of animals or organisms who do not breed in the wild, or who come from the same species but different locations, are not considered to belong to the same species. (What is a Species) One can see how unorganized this type of classification system would eventually become, having multiple species classified, when in reality they would all be the same species.

A final argument against the genotypic cluster concept would be that if species were defined and split by differences in DNA, where and how would they be divided and where would the dividing stop. This is an interesting thought and worthy of consideration. This author’s answer to that challenge would be not to divide the classification down to individuals, like Homo sapiens sapiens maryclark, but to the species in general of homo sapiens sapiens and other similar classifications.

Based upon scientific studies to date, and after comparing the many different concepts of species, this author still submits that the genotypic cluster definition of species is the truest concept of species that exists today. It gives a concrete difference that is clearly distinguishable through proper scientific testing. It is so clearly defined and effective that it can divide species and subspecies with great accuracy. It appears that as human thought has progressed through the ages, and as technology has advanced, the definition of species, as man in general sees it, has gone through a metamorphosis of its own. Because DNA studies are so well understood today, more people are adopting the genotypic cluster concept of species. Yet, as more scientific advances are made, there may emerge yet another even more accurate definition of species, as there is still so much more to learn regarding species. At this time, however, this author firmly submits the genotypic cluster definition of species to be her selection.

Now that the definition of species has been decided, a decision must be made in regards to the preservation of species, and which species we protect and which we don’t. There is a natural order of things wherein “the extinction of one species, the replacement of one by another, is as much a part of evolution as is the development of a new species.” (VanDeVeer, Pierce, 501) Letting “Nature take its course” so to speak up until now has in some cases been good, but in other cases been a struggle. Watching a species like the California condor come so close to extinction, and working to save it and bring it back, gives hope for other endangered species. But the question, of which endangered species have value and merit preservation, is one that is difficult to answer. One must be cognoscente of all species and what part they play in preserving our global environment as a whole. Holmes Rolston III said regarding species preservation: “The species too has its integrity, its individuality, its right to life (if we must use the rhetoric of rights); and it is more important to protect this vitality than to protect individual integrity.” (VanDeVeer, Pierce, 505) I agree with Mr. Rolston. It is too often when people make an individual decision to shoot a bird needlessly, just for fun, or to shoot a human being needlessly, just for fun. Whether a bird or a human, each is a living creature on Earth and deserves preservation. All life is important. There are those who say that the mountain lion population in California, which was once near extinction, is getting out of hand, and many farmers are losing sheep in great numbers and people are being attacked. But my opinion is that there are many brilliant minds in this world, and there has to be at least one person who can come up with a workable solution to solve this problem without killing mountain lions. An anthropocentric attitude would be to kill any lions that became a nuisance or caused trouble. The lions are only doing what comes natural to them. They are seeking food for survival. There are many instances, however, when certain species that are endangered have been preserved when in troubled situations, while others who are common have not been given a second thought. This author understands, as does Mr. Rolston, that:

Only the human species contains moral agents, but perhaps conscience on such an Earth ought not to be used to exempt every other form of life from consideration, with the resulting paradox that the sole moral species acts only in its collective self-interest toward all the rest. (VanDeVeer, Pierce, 511)

It is the opinion of this author that all species have value and thus, should be treated with respect. One should not favor one species, while discarding the rest.

Humans should take into consideration the well being of the world as a whole when deciding which species matter and which should be preserved. They should use their conscience in making this decision. This is why humans have a conscience. There needs to be a balance of plant and animal life upon the Earth. The plant kingdom receives the least amount of consideration, mainly because it has no voice of its own. In many cases, the plants provide nourishment to people as well as to animals as they are used for food. There needs to be equality in the protection of all species, so that they can flourish on this Earth. Since human beings are the only species that can control this situation, it is up to them to do so. All citizens must work together as a global community and preserve the resources that are still available. Global citizens must learn not to waste, and they must learn to respect all that is around them. If they can do this, they will preserve species and our ecosystem for lifetimes to come.

Works Cited

Mayr, Ernst. “What is a Species, and What is Not?” Philosophy of Science, Vol. 63. June 1996. PP. 262-277.

National University. “What is a Species?” www.adera.be/fish/whatspecies.html

Peterson, Ronald H. Bioscience Online. “Species and Speciation in Mushrooms: Development of a Species Concept Poses Difficulties.” 1999.

http:// www.findarticles.com/m1042/6_49/54823662/p1/article.jhtml

Teed, Rebecca. The Phyletic Gradualism – Punctuated Equilibrium Debate. April 1998.

http://lrc.geo.umn.edu/people/teed/papers/macroev.html

VanDeVeer and Pierce. The Envionmental Ethics and Policy Book. 1998.