I don't know that subjectivity is necessarily a bad thing (of course, that is a subjective judgement!), as long as we recognize that we do certain things based on preferences and define/defend what those preferences are. I suppose the problem is that not everyone will have the same preferences. Where things get dangerous is if we misconstrue our subjective preferences as objective facts. Unfortunately, confusion between our subjective preferences (or anti-exotic biases) and the objectively demonstrated impacts of exotic species on ecosystems has sometimes found its way into the scientific literature (e.g., hearsay on the negative effects of tamarisk treated as scientific fact... as Matt Chew and others have demonstrated).
Mark D. Dixon Assistant Professor Department of Biology University of South Dakota Vermillion, SD 57069 Phone: (605) 677-6567 Fax: (605) 677-6557 Email: mark.di...@usd.edu -----Original Message----- From: Ecological Society of America: grants, jobs, news [mailto:ecolo...@listserv.umd.edu] On Behalf Of James J. Roper Sent: Thursday, May 13, 2010 11:20 AM To: ECOLOG-L@LISTSERV.UMD.EDU Subject: Re: [ECOLOG-L] Ecology Terminology and associated phenomena Colonizing species etc Matt has important points. 1. Alien is from somewhere else (that is, it's recent evolutionary history does not include its current location) and natives are from the place where they reside. AFTER that definition, we come to think that aliens are different than residents, and we often find they are (not surprisingly) and are not. Many marine species have unknown historical ranges, so we have no idea where thare are from, and we call those cryptogenic (hidden origins). 2. Whether organisms are bad for being alien is a judgement call, and subjective. Sure, we can say that they cost money, but that only means that they inconvenience us in some way - still subjective. Sure we can say that they change community dynamics, but does the community care? If evolution were allowed to run its course, I am sure that we would all agree than in another million years or so, all the current aliens will have become natives (adapted for where they are, and fitting - in some way - in the community at that time). Thus, the VALUE statements about aliens and invasives are invariably subjective. 3. Politics is about appealing to emotion to justify getting money (and science is often politics). The trend that this breeds is to inflate the value of whatever it is that we want money for. So, how do we justify spending billions on invasive species control? Economically, not scientifically. My objective, scientific reasons for justifying the removal of invasives and alien species are, in fact, subjective. After all, even Elton said it well, although subectively - and I paraphrase - the continued introductions of species will have the net effect of reducing biodiversity, simplifying interactions in nature, and making the world a less interesting place. I can see a future where ecologists study how introduced species have adapted to their adopted homes, how new interactions evolve in communities dominated by introduced species, how biodiversity changes over time with introductions and extinctions. We will have a whole new science of biogeography - rather than Hubbell's "Unified Neutral Theory of Biodiversity and Biogeography" we will have someone's "Unified Neutral Theory if Biodiversity due to Introductions and Extinctions." I can't help but (subjectively) think that such a place will be much poorer than our natural world of today (and I recognize how much poorer our natural world of today is compared to that of Darwin, for example). Cheers, Jim Matt Chew wrote on 13-May-10 11:59: > Under the terminology and definitions promoted by leading invasion > biologists including David Richardson and Petr Pyšek, 'alien' species and > their subset 'invasive' species are not routinely identified by their > ecological characteristics. Aliens are identified by subtracting historical > local biotas (meaning species lists) from recent local biotas, then deciding > which positive bits of the difference can plausibly be attributed to > dispersal via human agency. Invasive species are a subset of aliens: those > with the capacity to spread, identified simply by having done so, > somewhere.
