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Chapter 14: Slide 3 of 17
Increase in Population Size
Once introduced to a new area, a species can start spreading. As with introductions, species can spread on their own or with our help. Their ability to increase their population size after introduction can be assisted by the lack of effective population controls such as predators, parasites, competitors, and/or diseases. These population control agents are ineffective because the they did not evolve with the introduced species. In addition, if the introduced species is a predator, parasite, or disease organism, it's ability to become invasive is assisted by the native prey's or host's lack of effective defenses, again because the native species did not evolve with the introduced species. Unlike most animals, plants can expand the area they occupy without producing offspring, by sending out new shoots, stems and roots (rhizomes). In the photo above, giant salvinia has overtaken the whole lake by simply growing new fronds that break off as new individuals.1. Introduction and Spread of AIS
