Re: Tendency towards Gigantism with colder climates...

[James Mahaffy <mahaffy@xxxxxxxxx>]

Kaori,

	At least part of the answer has to do with the ratio of surface area
(which is where you lose heat) to volume of cells (which metabolically
produce heat).  You have a better ratio (less percentage surface area
with greater size). The arctic foxes and bears are bigger than their
more southern brethren (although usually with smaller extremities).

	Most colder climates or latitudes also have more severe winters that
you somehow have to survive. 

There are more complicated answers, but I think the principles above are
part of the answer. 
> 
> 
>      I am currently working on researching for a seminar for a third
> year Evolutionary Paleoecology class.  My topic is the correlation
> between size and climate, re:  the tendency towards gigantism as the
> climate becomes colder.  For example, why mammals seem to have gotten
> larger during glacials and tended to get smaller during the
> interglacials?  I was wondering if anyone has any good
> references on why this occurs, or any other relevant information. 
> Please get in touch ASAP if you have any ideas....Thank you very much!
> 
> Kaori   
> 
> ----------------------------------------------------------------------
> kaori torigai
> Environmental Science
> Carleton University
> 
> Email address: ktorigai@chat.carleton.ca
> ----------------------------------------------------------------------

-- 
:
James F. Mahaffy                   e-mail: mahaffy@dordt.edu
Biology Department                 phone: 712 722-6279
Dordt College                      FAX 712 722-1198
Sioux Center, Iowa 51250