Difference between revisions of "Species"
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| − | A '''species''' is a group of living beings or organisms having | + | A '''species''' is a group of living beings or organisms having sufficient genetic similarity to be able to interbreed and produce fertile offspring.<ref>A group of organisms belong to the same biological species if they are capable of interbreeding to produce fertile offspring. [http://www.biochem.northwestern.edu/holmgren/Glossary/Definitions/Def-S/species.html Holgrem Lab], Northwestern University, Illinois </ref> |
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| + | For example, a [[tiger]] and a [[clam]] are different species, because they cannot mate. A [[German Shepherd]] and a [[Beagle]] can mate, because they are different breeds within one species. | ||
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| + | However, the definition of "species" has changed over time and is sometimes problematic. | ||
| + | For example, there are cases where two species are not capable of interbreeding, but each is capable of interbreeding with a third species.<ref name="spark">[http://www.sparknotes.com/biology/evolution/speciation/section1.html Speciation] (SparkNotes)</ref> | ||
| + | Additionally, a "species" is sometimes defined in such a way that groups of creatures that do not ''naturally'' interbreed (perhaps because of geological isolation) are classified as separate species despite the fact that they ''can'' interbreed.<ref name="spark"/> | ||
| + | Furthermore, many extinct species known only from fossils have been given species names, despite the impossibility of determining their capability of interbreeding. | ||
==The origin of species== | ==The origin of species== | ||
Revision as of 14:32, August 7, 2007
A species is a group of living beings or organisms having sufficient genetic similarity to be able to interbreed and produce fertile offspring.[1]
For example, a tiger and a clam are different species, because they cannot mate. A German Shepherd and a Beagle can mate, because they are different breeds within one species.
However, the definition of "species" has changed over time and is sometimes problematic. For example, there are cases where two species are not capable of interbreeding, but each is capable of interbreeding with a third species.[2] Additionally, a "species" is sometimes defined in such a way that groups of creatures that do not naturally interbreed (perhaps because of geological isolation) are classified as separate species despite the fact that they can interbreed.[2] Furthermore, many extinct species known only from fossils have been given species names, despite the impossibility of determining their capability of interbreeding.
The origin of species
Most Americans believe that God created the different species of plants and animals in six days of Creation (Genesis chapter 1). Religious faith on this is divided into Young Earth Creationism (the process started less than 10,000 years ago and took a short time) and Old Earth Creationism (the process began hundreds of millions of years ago and took millions of years).
Charles Darwin wrote The Origin of Species 167 years ago, hoping to account for the diversity of plant and animal life with an entirely naturalistic explanation (see Theory of evolution).
Note
- ↑ A group of organisms belong to the same biological species if they are capable of interbreeding to produce fertile offspring. Holgrem Lab, Northwestern University, Illinois
- ↑ 2.0 2.1 Speciation (SparkNotes)