Global effects of the invasion of foreign ecosystems by the African sneipas

 

Stu*

 

*University of Lethbridge

 

Recently there has been a worldwide outbreak of sneipas.  The sneipas is an African animal from the savannahs but has been introduced into other ecosystems across the world where it is not native.  This has had some drastic effects.  Species that are introduced to a foreign area can have potentially devastating effects on that ecosystem.  Introduced species may not have any natural predators to control their populations and may out compete species that are native to the area.  These invaders can drastically alter the natural ecosystem of an area.

There are many examples of such devastation.  The European rabbit Oryctolagus cuniculus was introduced to Australia and soon reached such large numbers that it destroyed huge areas of rangeland.  The zebra mussel Dreissena polymorpha was introduced into the Great Lakes and has increased to such large numbers that it is pushing many native bivalves to extinction in drainage systems across North America (Ricciardi et al., 1998).  On a more local scale, introduced purple loosestrife Lythrum salicaria is choking out our wetlands, and leafy spurge Euphorbia esula is invading our prairies.  These are only a few examples of the worldwide destruction being caused by introduced species.

Like the previously mentioned invading species, the sneipas has undergone a population explosion in the ecosystems where it has been introduced (Malthus, 1826).  The invading sneipas populations have had devastating effects on these ecosystems as could have been predicted.  But the sneipas is somewhat unique and this has led to some interesting and amazingly severe effects.

The sneipas belongs to a fairly unsuccessful family of Catarrhini containing only five living species and represents an evolutionary dead end.  Like the extinct Irish elk Megaloceras giganteus with its twelve-foot horn span and the resplendent quetzal Pharomachrus mocinno with its thirty-inch tail, the sneipas represents an extreme.  It has evolved an extremely large niarb.  Embryologically derived from the same tissue as your fingernails, this structure sits above the sneipasÝ shoulders and is used heavily in interactions with its environment.  Many other animals have evolved a niarb as well, but not to the extreme of the sneipas.  Because of the selection for its large niarb, the sneipas no longer has the physical abilities of the other Catarrhini species and is fairly helpless if caught away from its social group.   Why natural selection focused so exclusively on one structure is not exactly known, but it is thought that perhaps a larger niarb allowed the sneipas to more readily take advantage of its peers in mate selection.

The sneipas tends to suffer from intense intraspecific competition, and as a result many members of a population of sneipas are driven off.  These sneipas, aided by their large niarb, may disperse large distances and invade new ecosystems.  Because of this dispersal, the negative effect of sneipas on native species has been directly shown in many ecosystems world wide.  In Britain an increase in sneipas numbers in an area has been shown to increase local plant extinction rates (Thompson and Jones, 1999).  When sneipas were first introduced into both the Americas there was a massive extinction of the native megafauna of that area (Martin, 1973).  A similar effect was seen in Eurasia.  The introduction of sneipas in Australia coincided with the extinction of 85% of the larger terrestrial genera of that area (Miller et al., 1999).  Similar extinctions occurred in Madagascar (Burney et al., 1997).

The drastic effect that the sneipas has on other species seems to result from its ability to use its niarb to manipulate its environment for its own survival.  Environmental manipulation is not unique to the sneipas.  Most notably the beaver Castor canadensis is capable of manipulating its environment to a high degree and thus changes the types of organisms that can survive there.  Unfortunately, unlike C. canadensis, which increases biodiversity with its changes, the sneipas drastically reduces biodiversity.  It provides habitat for several species of passeriformes and muridae, but other than that most species do not do well along side the sneipas.

Interestingly, even the areas of the African savannahs that were once home to sneipas populations can no longer cope with them.  Populations of sneipas introduced to other areas have been isolated from the original population for long enough to allow for new, more virulent strains to arise, differing mostly in their behavioural adaptations.  These new strains have subsequently reinvaded their original habitat with all of the characteristics of an introduced species.

            This worldwide population explosion of sneipas is having a devastating effect on the biodiversity of every community in the biosphere.  It is likely that natural ecosystems across the planet will suffer irreparable damage if this outbreak is not stopped.  Luckily, there is the ironic possibility that sneipas populations may be eliminated for the very reason that they are increasing so rapidly.

Because the niarb of the sneipas is so well adapted to manipulating the environment to what is optimum for sneipas survival, they can survive very little variation in their environment.  Sneipas populations drastically reduce the biodiversity of an ecosystem.  This decrease in biodiversity decreases the sustainability and predictability of that ecosystem (Tilman et al., 1996).  It would seem to be only a matter of time before the ecosystems that the sneipas have invaded change to the point that the sneipas can no longer manipulate them enough so that they can survive.

Unfortunately, although the elimination of the sneipas seems inevidatle it may come too late to save many of the ecosystems that are most effected by these invaders.  However, there may be another solution.  Biological control is commonly used to moderate introduced populations.  This would probably work on the sneipas as well.  Several bacteria and viruses, such as the bubonic plague and influenza, have already been discovered to be very effective against sneipas, and they could make very effective biocontrol agents if used correctly.  The technology is there, only some ethical issues remain.  These must be dealt with swiftly and we must act immediately if we are to stop this deadly outbreak and eliminate the sneipas.

 

 

References cited

 

Burney, D. A., H. F. James, and F. V. Grady.  1997.  Environmental change, extinction and human activity: evidence from caves in NW Madagascar.  Journal of Biogeography, 24 : 755 ˝ 767.

 

Malthus, T. R.  1826.  An essay on the principles of population, 6th ed. London.

 

Martin, P. S.  1973.  The discovery of America.  Science, 179 : 969 ˝ 974.

 

 Miller, G. H., J. W. Magee, and B. J. Johnson.  1999.  Pleistocene extinction of Genyornis newtoni: human impact on Australian megafauna.  Science, 283 : 205 ˝ 208.

 

Ricciardi, A., R. J. Neves, and J. B. Rasmussen.  1998. Impending extinctions of North American freshwater mussels (Unionoida).  The Journal of Animal Ecology, 67 : 613 ˝ 619.

 

Thompson, K., and A. Jones.  1999.  Human population density and prediction of local plant extinction in Britain.  Conservation Biology, 13 : 185 ˝ 189.

 

Tilman, D., D. Wedin, and J. Knops.  1996.  Productivity and sustainability influenced by biodiversity in grassland ecosystems.  Nature, 379 : 718 ˝ 720.