Expert: Dana Krempels, Ph.D. - 9/10/2007

Question
Hi,
I have two questions :
1- I am wondering what are the creatures that has 46 chromosomes other than the humans.
2 - How can I know the chromosome number of a specific creature, is there a website that helps ?

Many thanks .

Answer
Dear Najeeb,

This is a difficult question to answer, since karyotype information on various species is sparse and usually scattered around the literature.  There are probably *many* species with 46 chromosomes, likely scattered across many taxonomic categories.  

I know of a deer species (Muntjacus reevesi ) and a species of wild rat (Rattus sensu) that have 46 chromosomes, but there are undoubtedly many other species with that same number that I don't know about.  

It is not the *number* of chromosomes that determines a species' identity, but the *information* encoded therein.  Chromosome number is relevant to evolution only in that it may allow us to determine whether closely related species may have differentiated, in part, due to chromosomal mutations that may affect chromosome number.  But other than that...?

There is no single web site I know that lists the chromosom numbers of many different species.  But you can easily find out whether the c'some number of a species is known by calling up our old pal Google and typing in either "species X chromosome number" or "species X karyotype".  That should get you what you need, if it is available.

Hope that helps!

Dana