Editing Allen's rule (section)

==Mechanism==

A contributing factor to Allen's rule in [[vertebrates]] may be that the growth of [[cartilage]] is at least partly dependent on temperature. Temperature can directly affect the growth of [[cartilage]], providing a [[proximate]] biological explanation for this rule. Experimenters raised [[mice]] either at 7 degrees, 21 degrees or 27 degrees Celsius and then measured their tails and ears. They found that the tails and ears were significantly shorter in the mice raised in the cold in comparison to the mice raised at warmer temperatures, even though their overall body weights were the same. They also found that the mice raised in the cold had less blood flow in their [[Limb (anatomy)|extremities]]. When they tried [[Bone growth|growing bone]] samples at different temperatures, the researchers found that the samples grown in warmer temperatures had significantly more growth of cartilage than those grown in colder temperatures.<ref>{{cite web |title=Hot weather for longer legs |website=Science News |publisher=The Naked Scientists |date=December 2008 |url=http://www.thenakedscientists.com/HTML/content/news/news/1549/}}</ref><ref>{{cite journal |last1=Serrat |first1=Maria A. |last2=King |first2=Donna |last3=Lovejoy |first3=C. Owen |year=2008 |title=Temperature regulates limb length in homeotherms by directly modulating cartilage growth |journal=[[Proceedings of the National Academy of Sciences]] |volume=105 |issue=49 |pages=19348–19353 |doi=10.1073/pnas.0803319105 |pmid=19047632 |pmc=2614764 |bibcode=2008PNAS..10519348S |url=http://www.pnas.org/content/105/49/19348.full.pdf|doi-access=free }}</ref>