Species
- A species can be defined as:
A group of organisms that can interbreed to produce fertile offspring
- The ability to breed and produce fertile offspring is a useful method of distinguishing species for organisms that reproduce sexually but can be difficult to apply in some situations
- Organisms that reproduce by asexual reproduction, such as bacteria, cannot be classified using this method
- On rare occasions, animals of different species breed together and produce fertile offspring, such as the so-called 'wholphin'; the fertile offspring from a cross between a melon-headed whale and a common bottlenose dolphin
- According to the species rule above the wholphin would be a new species, but while scientists do believe that hybridisation can lead to new species it needs to be a frequent event for this to occur, and wholphins are rare
- Note that the melon-headed whale is actually a species of dolphin, so the name 'wholphin' is a bit inaccurate!
- The imperfect nature of this method of classifying species means that other characteristics are often used at the same time
- Organisms of the same species share similar morphology
- DNA sequences can be compared, with a certain level of similarity indicating that organisms are the same species