It's a matter of temporal and spatial scale. It's one thing if species are arriving via trans-oceanic dispersal on their own power every million years or so, and quite another if they're arriving via jet every decade or so. Similar, species range expansions are of much more limited concern if only small areas are added to the range, perhaps over thousands of years, than if ocean and air travel can get them to many different places at once.
So ... not all colonization events occur in what most of us regard ecological time, and I say that as someone in the field who is regarded as seeing (via calibrated molecular phylogenies) evidence for a relatively large amount of long-distance dispersal. And, ecologically, there is all the difference in the world between seeing a rock or two occasionally rolling downhill ... and getting buried in an avalanche. In Hawaii, it's estimated that fewer than 300 long-distance dispersal events were successful over the last 5 million years in establishing the native flora. By comparison, over the 300 years post-Cook, more than 1000 additional plant species have become established there. Numbers of species are probably important in terms of increasing the chance of a pernicious weed appearing, free of the natural enemies that held it in check on its long-established home range but which didn't disperse with it. Given enough time, new natural enemies to such "unchained plants" will indeed evolve, but that might take hundreds or thousands of years, and in the interim those super-plants can wreak tremendous damage. Tom Givnish On 10/29/13, Madhusudan Katti wrote: > I’m not sure I understand this difference either. > > Don't all colonization events occur in ecological time? Whether it is through > their own “natural” dispersal efforts, traveling under their own power, or > through assistance by wind / water currents or other species that move faster > or over longer distances (be they migratory birds to whom you cling, or > airplanes in whose holds you may be transported, perhaps deliberately), every > colonizing species does so through a few individuals reaching a new patch of > habitat. How is there a fundamental difference in the ecological / > evolutionary outcomes that result from such colonization events? > > Madhu > > ~~~~~~~~~~~~~~~~~ > Dr. Madhusudan Katti > Associate Professor, > Department of Biology, M/S SB73 > California State University, Fresno > 2555 E San Ramon AVe > Fresno, CA 93740 > > http://about.me/mkatti > > On Oct 29, 2013, at 8:12 AM, Meg Ballard <mball...@udel.edu> wrote: > > > The difference is the scale of invasion, both temporal and spatial. > > > > There is a difference in moving from one pond to an adjacent one, where > > your natural enemies and competitors are likely to exist, vs > > intercontinental or oceanic movements that occur in short time scales > > rather than evolutionary time scales. > > > > > > On Tue, Oct 29, 2013 at 10:45 AM, malcolm McCallum < > > malcolm.mccal...@herpconbio.org> wrote: > > > >> I mentioned this correspondence to a friend who works a lot in this > >> field. This is what he/she said (i'm leaving off the name since > >> he/she is not available to ask permission to expose it right now!): > >> > >> "What I absolutely can't stand is the term "invasion biology". It's > >> colonization theory pure and simple. Anything can invade. Painted > >> Turtles or Green Frogs to a new farm pond. Besides being misused, I > >> think that the term prejudices the research approach. As for the > >> debate, the best arguments against studying exotic species and their > >> impacts are embarrassing." > >> > >> What has caused us to move from using "colonization theory" and to the > >> new term "invasion biology?" Are they really different? I don't see > >> a difference either. > >> > >> On Mon, Oct 28, 2013 at 9:58 AM, lisa jones <lajone...@hotmail.com> wrote: > >>> > >>> > >>> > >>> > >>> > >>> > >>> A quick and interesting editorial piece from Richardson & Ricciardi > >> "Misleading criticisms of invasion science: a field guide" in Diversity and > >> Distributions (2013, 19: 1461-1467). > >>> > >>> A link to the article can be found here on the Canadian Aquatic Invasive > >> Species Network (CAISN) website (listed near the bottom of the page): > >>> http://www.caisn.ca/en/publications > >>> > >>> I am sure there will be a response from those who see no value in > >> invasion science but as one reviewer pointed out "when invasions are driven > >> by us (ballast waters, trade, aquaculture, you > >>> name it) and overcome wide ecological barriers... well, I would be very > >>> careful in saying that there is no problem." > >>> > >>> Lisa > >>> > >>> > >>> > >>> > >>> > >> > >> > >> > >> -- > >> Malcolm L. McCallum > >> Department of Environmental Studies > >> University of Illinois at Springfield > >> > >> Managing Editor, > >> Herpetological Conservation and Biology > >> > >> > >> > >> "Peer pressure is designed to contain anyone with a sense of drive" - > >> Allan Nation > >> > >> 1880's: "There's lots of good fish in the sea" W.S. Gilbert > >> 1990's: Many fish stocks depleted due to overfishing, habitat loss, > >> and pollution. > >> 2000: Marine reserves, ecosystem restoration, and pollution reduction > >> MAY help restore populations. > >> 2022: Soylent Green is People! > >> > >> The Seven Blunders of the World (Mohandas Gandhi) > >> Wealth w/o work > >> Pleasure w/o conscience > >> Knowledge w/o character > >> Commerce w/o morality > >> Science w/o humanity > >> Worship w/o sacrifice > >> Politics w/o principle > >> > >> Confidentiality Notice: This e-mail message, including any > >> attachments, is for the sole use of the intended recipient(s) and may > >> contain confidential and privileged information. Any unauthorized > >> review, use, disclosure or distribution is prohibited. If you are not > >> the intended recipient, please contact the sender by reply e-mail and > >> destroy all copies of the original message. > >> -- Thomas J. Givnish Henry Allan Gleason Professor of Botany University of Wisconsin givn...@wisc.edu http://botany.wisc.edu/givnish/Givnish/Welcome.html
