An interesting discussion of the problems concerning the adaptive nature of growth rates appears in "Adaptive intrinsic growth rates:an integration across taxa" by JD Arendt. It is in Quart. Rev. Biol 72 (2):149-177 (1997). Alan Alan H Brush brushes2@juno.com 92 High Street Mystic, CT. 06355 (860) 572-1717