Jamieson on Natives versus Exotics

(with some Hettinger additions)

pp. 175-180


1.      Virtually all environmentalists prefer native to exotic (non-native) species.

         a.      Should they? What are natives?


2.      Possible definition #1: Exotic species are human-introduced species

         a.      A species is exotic to an environment if would not be there w/o human action

         b.      Examples: European rats that tagged along on voyages of discovery now all over U.S.; Kudzu; Zebra Muscles; Asian Carp

         c.      Problem: Counts some species as exotic, when clearly native

                  i.      Species humanly-introduced but then evolves into a new species–is native as evolved here and is endemic (found no where else)

                           (1)    Salt cedar introduced as ornamental plant and now all over desert Southwest (has evolved into a new species?)

                  ii.     Species restored by humans can be native (Yellowstone Wolves), but would not be there w/o human action

         d.      Problem: Counts some species as native, which are clearly exotic

                  i.      When finches first made it to Galapagos Islands 10,000 years ago, got there on own but clearly exotic

                  ii.     Cattle egret, blown over by wind from Africa to South America where exotic when first arrived


3.      Possible definition #2: Species exotic when occurs outside of its historical range

         a.      Handles cases of rats, salt-cedar, and finches

         b.      Problem: Historical range can shift

                  i.      Once were palm trees in Canada, but if planted one there now, it would be exotic

         c.      Problem: How far back in time do we go to assess species historical range?

                  i.      Before 13,000 years ago there were camels, elephants and cheetahs in North America

                  ii.     If we introduced their African cousins, would that count as native species reclaiming historical range?

                           (1)    Or even if they got here on their own?

         d.      Problem example: When a species migrates out of its historical range but is still with species it has co-evolved with it does not seem to be exotic.

4.      Possible definition #3: Species exotic if not well integrated into ecological community (so causes damage?)

         a.      Problems

                  i.      Lots of exotic organisms have no demonstrable impact on ecosystems (so not damaging).

                  ii.     Some native species go wild and “unbalance” ecosystem (are not well integrated)

                           (1)    Asian-Long-Horned Beetle damages trees in Chicago and in native range

                           (2)    Mountain pine beetle deforesting large areas of the west are native

5.      Hettinger definition of exotics: An exotic species is one that is foreign to an ecological assemblage in that it has not significantly adapted to the local biota and abiota and they have not significantly adapted to it

         a.      Exotic species can naturalize over time;

                  i.      Wolves got to North America tens of thousands of years ago crossing Bering land bridge and are now native.


6.      Jamieson thinks “exotic species” is a value laden term and we must balance those values against others

7.      So in many cases eliminating exotics may be worse than tolerating them

         a.      Worried about saving nature by exotics elimination as a “war against the unwanted”

         b.      Some contend that it is wrong to object to nonnatives because of their origin and that, except in the rare cases in which they are extremely harmful and workable control strategies are available, they should be embraced as “fellow inhabitants of planet earth.”


8.      The Xenophobia criticism of dislike of exotics

         a.      The preference for natives is ethically problematic because it is based on — and reinforces — a common prejudice against things foreign

         b.      The military rhetoric used about nonnatives —“invasion biology,” “war on exotic species,” “the threat from alien invaders”— fits a xenophobic worldview.

         c.      The analogy between “ biological nativists ” (or purists) who favor native species over exotics and cultural nativists (or purists) who object to the mixing of races and cultures is instructive and worrisome.

         d.      It is unlikely that those who oppose nonnative species believe in the inferiority of these foreign immigrants as is typical with xenophobic cultural purists afraid of “biological pollution” from “lesser” races


9.      The homogenization/cosmopolitinization objection to exotic species

         a.      Biological nativists’ objection to nonnative species can be defended as a way to protect the diversity of the planet’s ecosystems from the homogenizing forces of globalization.

         b.      Replacing Earth’s diverse biological communities with a planet of weedy, cosmopolitan species would be tragic

         c.      Keeping a dandelion out of Yellowstone is much like keeping Wal-Mart out of a small New England town or McDonalds out of India

         d.      Kudzu in the American South is like commercial television in Nepal, a threat to the diversity of the planet’s communities and ways of life

10.    Reply:

         a.      Some believe that the mixing and blending of flora and fauna from around the world will not lead to homogenization but instead to hybridization and new forms of diversity

         b.      Introductions of species can provide the long-term residents with new ecological and evolutionary prospects

                  i.      Much like how “the influx of new minds and perspectives” into a business or academic field can enhance its vitality, diversity, and longevity”

Questions on Jamieson (and Hettinger) on Natives vs. Exotics

1.      Describe at least two definitions of exotic species and give examples that those definitions have trouble accounting for.

2.      Does Jamieson think it an important environmental goal to eliminate all exotic species? Do you?

3.      Explain and evaluate from your own perspective the xenophobia criticism of those environmentalists who oppose exotic species

4.      Explain and evaluate from your own perspective the worry that human introductions of exotics will homogenize the world’s ecology.