Evolutionary Responses of Natives to Introduced Species.

The evolutionary responses of many native species to the introduction and invasion of non-native species whether they be plant or animal are often overlooked. This may be because when an introduced species becomes established in an area it seems to totally desimate the native population with no orvert defense shown by the native species. But infact there are many defense responses by native species,the most common responses include altered anti-predator defenses, changes in the spectrum of resources and habitats used, and other adaptations that allow native populations to persist in invaded areas (Carroll, et al 2006).

Just how well a native population can evolutionarily respond to the introduction of non-native species depends on just how aggressive the introduced species is, the genetic makeup for the native species, history of previous non-native invasions and the genetic variabilty of the native population. If there is a strong degree of variability within the native species it gives them a much greater chance of maintaining their population numbers. In a small number of cases where there is low genetic viarability and there has been previous invasions that caused serious limitations to the populations of native species, these native species willnatives will fail to evolve or otherwise adapt, and local or global extinction will result.

In other cases, adaptive change in natives may diminish impacts of invaders and potentially promote coexistence between invaders and natives (Carroll, et al 2006). Understanding the evolutionary component of non-native/ native species interactions is invaluable to showing the long-term impacts of invasions, and to understanding the role of evolutionary processes in the assembly and dynamics of natural communities.

References:

S.P. Carroll, J.A. Lau, S.Y. Strauss. (2006) Evolutionary Responses of Natives to Introduced Species: What do Introductions Tell us About Natural Communities. Ecology Letters. Vol. 9 pg. 375 - 374.