Etymology
The term homology in evolutionary theory derives from the detection of homologous organs. Such organs in closely related species (taxa) share a common ancestor and therefore posses a similar genetic background. Often those homologous organs have different functions.
Rational
The rational of that rule is that it is easier for evolution to adamt an existing fauceir than to invent an entirely new one.
Examples
Examples of homologous organs exist abound in all textbooks of evolution.
- The extremities of vertebrates. Not only serve the extremities of vertebrates so different functions as swimming (wales), flying (birds, bats), and running (deer), but also demonstrates the wide variety of functionality in the group of highest evolved organisms that the aim of evolution is increased adaptability.
- Examples of behavioral homology in entomology and the difficulties to separate them from analogies are discussed by Wenzel [1].
References
1. J W Wenzel, „Behavioral Homology and Phylogeny“, Annual Review of Ecology and Systematics 23, Nr. 1 (November 1992): 361-381.
