> When I was at school (many years ago!) we were taught that the difference between a species and a strain is that the former can't cross and produce fertile offspring Surely you jest, Chris! Where does that leave species that do not reproduce sexually? > genetic material can be exchanged through viral transportation, through picking up stray DNA in the medium after a cell has broken apart, or by deliberate insertion of small rings of DNA, called plasmids. "Horizontal" or "lateral" genetic transfer is probably as old as life itself. > some lizards are parthenogens; and have no males, where their nearest relatives are sexual, but in that case they are like their sexual cousins ecologically and morphologically > there are n+1 definitions of "species" in a room of n biologists. -- John Wilkins *********************************************** The BEE-L mailing list is powered by L-Soft's renowned LISTSERV(R) list management software. For more information, go to: http://www.lsoft.com/LISTSERV-powered.html Guidelines for posting to BEE-L can be found at: http://honeybeeworld.com/bee-l/guidelines.htm