What kind of man you are? See a translation. Species is a scientific term and applies to living things animals, plants, bacteria, etc. It is one of the categories of classification. You would not say "all species of people" because there is only one species of humans. Highly-rated answerer. The one learning a language! Learn about premium features. Like many professional taxonomists Darwin wrote the first and still one of the best descriptions of barnacles , he found the constant squabbling about whether this variety or that was a separate species or the same to be a nuisance to doing the work.
In the Origin , he wrote: … it will be seen that I look at the term species as one arbitrarily given, for the sake of convenience, to a set of individuals closely resembling each other, and that it does not essentially differ from the term variety, which is given to less distinct and more fluctuating forms.
The term variety, again, in comparison with mere individual differences, is also applied arbitrarily, for convenience's sake. On the basis of this and other comments, he seemed to be saying that a species was not a real thing, but that it was just what we called something for convenience.
But in his works overall, he treats species as real things, mostly but not always isolated by infertility, with different ecological adaptations. His point was, and it remains a sticking point today, that the difference between a species and a variety within a species was vague.
This, of course, is due to the fact that species, like sand dunes, rivers and clouds, have no hard and sharp boundaries between them because of evolution.
About the time evolution had been universally accepted by naturalists now called biologists , but before the new Darwinism of the synthesis of genetics and evolution had been settled, one EB Poulton wrote a paper in entitled "What is a species? This set the agenda for the next century. From being the useful identification of kinds that might vary, in the late Middle Ages and after, through to being a problem of who got to name species and how they were to be differentiated, now species were the "units" of evolution, and of biology in general.
And a veritable explosion of attempts to define species followed. By the end of the 20th century, there had been some 22 distinct concepts identified by RL Mayden, and depending on how one divides them, some few others have been added. By my count, there are around 26 concepts see sidebar, p 42—3.
Well, not exactly concepts. There is only one concept , which we label by the word "species". There are 26 or so conceptions , or definitions, which we define in other ways. This slightly picky philosophical point matters. We are arguing over the best way to define a concept. This depends on scientific data, theory, and other factors some of them political, within the scientific community.
We might deny that the concept even has a useful definition, or we might think that we have been misled by the use of a single word and seek a number of different concepts that serve the purposes of science and knowledge.
I mention this because one of the oft-repeated claims made by anti-evolutionists is that if we cannot define our terms, we cannot show that species evolve. This canard goes back to Louis Agassiz, the famous geologist and paleontologist, who single-handedly introduced America to biology.
Agassiz wrote: [I]f species do not exist at all, as the supporters of the transmutation theory maintain, how can they vary? And if individuals alone exist, how can differences which may be observed among them prove the variability of species?
Darwin rightly snorted to Agassiz's one-time student Asa Gray: I am surprised that Agassiz did not succeed in writing something better. How absurd that logical quibble — "if species do not exist how can they vary? Creationists will often claim that they are not interested in the species level, though. Initially, creationism did require fixity of species. In the s, when George McCready Price equated "species" to the biblical "kinds", he was forced, to allow for the Ark to carry "every kind", to raise the bar higher.
Even this was not original. In the late 18th century, Buffon, Cuvier's predecessor, had suggested that there was a "first stock" from which all members of a kind had evolved, so that all cats evolved from an original animal, modified by geography and climate, for instance.
So creationists themselves have a "vagueness problem" no less than evolutionary biology does. Life is vague. Certainly the creationist "kind", or "baramin", as they mangle the Hebrew for "created kind", is extremely elastic.
Given that elasticity, the motivation for the inference that was made naturally during the 17th and 18th centuries that species do not evolve is undercut. If kinds are not exact in reproduction, why think that the Genesis account is enough to prohibit evolution? The answer is, of course, that biblical literalism is not the primary motivation here for opposition to evolution. The species problem Reproductive isolation conceptions It begins in , when a young fruit fly geneticist named Theodosius Dobzhansky published a paper "A critique of the species concept in biology" in a philosophy journal.
Not that there had not been developments after Darwin. Various people had suggested that species were "pure gene lines" or "wild-types" that did not vary much. Mendelian genetics caused a lot of debate about species. Dobzhansky claimed that a species was: … a group of individuals fully fertile inter se , but barred from interbreeding with other similar groups by its physiological properties producing either incompatibility of parents, or sterility of the hybrid, or both.
This was the original genetic version of reproductive isolation concepts Buffon had proposed interbreeding as a test a century and a half earlier, which Darwin rejected.
Unfortunately, a version framed by Ernst Mayr got called the "biological" species concept, in contrast to what were seen as "nonbiological" concepts that relied largely on form and based in museum taxonomy, which were called "morphological" concepts by Mayr.
Mayr's version changed over the years, but the one taught to most undergraduate biology students is the original: A species consists of a group of populations which replace each other geographically or ecologically and of which the neighboring ones intergrade or interbreed wherever they are in contact or which are potentially capable of doing so with one or more of the populations in those cases where contact is prevented by geographical or ecological barriers.
Or shorter: Species are groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups. Mayr's view was that species are formed when part of the species is geographically isolated from the main range and evolves in its own way such that when it gets back in contact, RIMs have evolved, as it were, by accident, and the two no longer interbreed successfully.
Selection against hybrids, which are, so to speak, neither fish nor fowl in ecological adaptations, then strengthens the isolation a process called "re-inforcing selection". Mayr's version of the origin of species, published in and reiterated for the next 60 years Mayr survived to , outliving many of his adversaries, and thus getting the last word , is called the allopatric theory of speciation.
It requires that RIMs evolve in place, so to speak, and the naysayers think this is unlikely to occur. If sympatric speciation does occur, then there can only be one reason — natural selection. Recent theoretical work shows that it is possible if the conditions are right. What we do not yet know for sure is how often the conditions are right. There is another uncontested class of speciation processes — usually involving hybridization, that old idea of Aristotle.
In plants particularly, but also in animals, fungi, bacteria, and so on, sometimes entire genetic complements can double, triple or more, resulting in a condition known as polyploidy. When this happens, sometimes the chromosomes and genes do not line up due to differing genetic structures of the parents, but an extra doubling of the genome, followed by a cell division, can give the cell a paired set of chromosomes, allowing it effectively to found a new species in one or a few generations.
When two species interbreed, this allows the resulting organism to have a matched set of chromosomes. It has also been seen in flowering plants, corals, grasshoppers, other insects, and reptiles. It is even hypothesized that the entire mammalian branch of the evolutionary tree was started with this kind of event. So in a sense, Linnaeus and Aristotle were right … sort of. By such tests, we know that horses, donkeys, and mules are all part of the same kind, even though they are classified as separated species.
So, if two organisms can interbreed and produce offspring regardless of whether the offspring are fertile , then the two organisms are the same kind. Some persons might be tempted to think that this implies that animals that cannot interbreed must be different kinds.
But that is an error in reasoning. While we can prove that two organisms are the same kind if they interbreed , we cannot definitively prove that two organisms are different kinds merely on the basis that they fail to interbreed.
To demonstrate that two organisms are separate kinds, we need other information. We need evidence that their ancestors are not biologically related. Studies in genetics can be very helpful in such determinations. Fossil evidence can also shed light on the issue.
The field of baraminology is an exciting and rapidly developing field in creation science. A horse and donkey are the same kind because they can interbreed. But they are classified as different species. Studies in baraminology have demonstrated that domestic cats and tigers belong to the same kind. Yet, they are classified as different species. The biblical teaching is that organisms reproduce organisms of the same kind but not necessarily the same species.
We would expect on the basis of Scripture that all organisms today are the same kinds as their original, supernaturally-created ancestors. We would expect, therefore, that we will not find transitional forms between the major categories of organisms — those that belong to separate kinds. Science confirms this. Cats give rise to cats and nothing else. Dogs beget dogs and nothing else.
We do observe a great deal of variation within the dog kind. Many breeds exist today that did not exist when God first created dogs. But we never observe a dog reproduce anything other than a dog. Paleontology confirms that this has always been the case. We find fossil evidence of variation within kinds of organisms as creation-based models predict. But we do not find compelling evidence of transitions between the major categories of organisms as evolutionary models would predict — such as a sequence of gradual transitions from invertebrates to vertebrates.
Considering that the hypothetical transformation from invertebrate to vertebrate would involve a complete and revolutionary inversion of structure, presumably such a process would be lengthy and would leave behind billions of transitions. Where are they? This is indeed the case with all major categories of organisms. Of course, there are occasional claims of a transition between some major categories. But these are nearly always disputed even by the evolutionists themselves.
In most cases, additional information reveals that such disputed specimens are fully within a given kind. We have seen so many examples of this, such as archaeopteryx, Nebraska man, Coelacanth, and so on. Clearly, the fossil evidence is consistent with the creation worldview, and challenges Darwinian evolution. You will find textbook examples of proof of evolution that involves a horse giving rise to… a horse, or a camel giving rise to a new variety of camel.
But they remain the same kind. Variation within a kind is biblical. In some cases, variations within a kind of organism lead to groups that are not able to interbreed with each other, and are therefore classified as different species. However, this is perfectly compatible with biblical creation.
But the organisms always remain the same kind. The creation scientist Carolus Linnaeus is considered the father of modern taxonomy. He recognized that God is a God of order and has created a wide variety of organisms with both similarities and differences such that they can be arranged into a logical hierarchy.
With slight modification, we still use the Linnaean system today. Organisms are classified from the broadest categories down to the most specific using the following hierarchy: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
We have already seen that the biblical kind is not necessarily the same as a species.
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