![]() ![]() Offspring) with one another, and that theyĬannot reproduce with organisms of other species (Mayr 1942). That the organisms within a species can reproduce (i.e., produce fertile Mayr claimed that what makes species different from sub-species and genera is There are multiple ways to detect species, and some may be better than others Know what an electron is, but that is not the same as knowing how to detect anĮlectron, when it is put into practical applications, has yielded multiple ways ![]() The situation is similar to what a physicist faces when trying to detect Practical procedures for identifying them. The same theoretical idea about species, but actually rely upon different It is possible that different scientists share While the practical procedure addresses the "how" question. The theoretical idea addresses the "what" question, Idea of what species are as well as a practical procedure for For example, biologists might have a theoretical The two questions are closely connected, but they are not Knowing how to discover species (i.e., having an answer to the "how" Having an answer to the "what" question) was basically the same as The past most biologists thought that knowing what species are (i.e., Species is part of the confusion around species (de Queiroz 2005). This business of having separate "what" and "how" questions about Finally, because the large majority of species come into existence gradually, it is not surprising that we have difficulty deciding when to identify new species or what the best way to do so should be. In other words, Darwin did not believe that there was a definite point at which a species came into existence. In his book, On the Origin of Species, Darwin famously wrote, "I was much struck how entirely vague and arbitrary is the distinction between species and varieties." (Darwin 1859). So if species are changing slowly, and if new species are formed at the slow pace of evolution, then we absolutely expect there to be cases where we struggle to decide whether two kinds of organisms should be grouped as separate species or as a single species. Darwin figured out a process by which species could change over time, and he believed that evolution was a slow and gradual process that played out over eons of time. To help understand the confusion and uncertainty over species, let's look at the most basic idea of Darwin's theory of evolution by natural selection. Alternatively, a newly discovered kind of organism might be so different from other known species that it receives not only a designation as a new species but also a ranking as a new genus. Each of these have been given the rank of sub-species. For example, the common chimpanzee species, Pan troglodytes, appears to include several slightly different kinds of chimpanzees. If you discover a new kind of organism then you must decide if it should be called a new species, or if it falls within an already described species. As a biologist you must also determine what level or rank of kind to assign to an organism. ![]() For scientific purposes, it is not enough to identify a kind of organism. For example, birds are a kind of organism, but birds are not a species -there are many thousands of species of birds. The central difficulty when studying species is that, even though all species are kinds of organisms, all kinds of organisms are not species. It also examines why an understanding of species is important, both for the study of biology and for our society. This article explores the idea of species, including both the meaning of the word species, and how biologists think species can be identified in nature. This disagreement is so well known, and so much discussed, that it is sometimes referred to by biologists as the "species problem" (Hey 2001). Biologists frequently disagree about species, and even argue over how best to define the word species. ![]() In fact, it is often a complex and difficult process-especially in cases of new or previously unknown species. But defining, identifying, and distinguishing between species really isn't that simple. For example, humans all belong to one species (the scientific name of our species is Homo sapiens), and we differ from other species, such as gorillas or dogs or dandelions. Quite simply, species are kinds, or types, of organisms. Most people have a basic idea of what species are, even if they are not sure of the best way to define the word species. ![]()
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