I think that the lack of a response is because there is no clear established rule about either but I suspect that folks have replied to Huang off list. Without academic references to back it up (I'm busy grading at the end of the semester) I will give two short answers based on what I have always been taught and used myself.
1. Invasive species are generally considered native when there are endemics that specialize on the invasive species. An example would be Larrea tridentata which is a relative newcomer to North America, having hitched a ride on migrating birds from S. America in the last 20,000-30,000 years and then rapidly spread throughout its current range. 2. Natives can be considered noxious (http://plants.usda.gov/java/noxiousDriver ) but the term invasive is generally not applied to natives. You have probably heard the term noxious weed before. This label is used regardless of the recent origin of the species. On a government policy level, the label "invasive" is restricted to non-natives (http://www.invasivespeciesinfo.gov/whatis.shtml ). -Erin Erin E. O'Brien, Ph.D. Department of Biological Sciences Dixie State College of Utah 225 South 700 East St. George, UT 84770 Phone: (435) 652-7761 Fax: (435) 656-4002 Email: obr...@dixie.edu -----Original Message----- From: Ecological Society of America: grants, jobs, news [mailto:ECOLOG-L@LISTSERV.UMD.EDU] On Behalf Of Wayne Tyson I will await the responses from others on the questions by Huang: 1. (When) do invasives become native? 2. Can natives become invasive?
