INVASIVE SPECIES DEFINITION Plants, animals, and microbes not native to a region which, when introduced either accidentally or intentionally, out-compete native species for available resources, reproduce prolifically, and dominate regions and ecosystems. Because they often arrive in new areas unaccompanied by their native predators, invasive species can be difficult to control. Left unchecked, many invasives have the potential to transform entire ecosystems, as native species and those that depend on them for food, shelter, and habitat, disappear.
Subspecies of pond slider family • Reddish stripe behind its eyes, may also be yellow • Body is dark olive with thin yellow stripes on its shell • Semi aquatic with webbed feet • Average length 5 to 13 inches • Males are smaller than females and have curved claws and also have longer and thicker tails • Live in lakes, streams, swamps, ponds and rivers • Omnivores • Cold blooded • Active from April to September • Native to Southern and Midwestern United States BIOGEOGRAPHY OF THE RED-EARED SLIDER
Pr0s Cons Become too large to contain and feed, looses appearance, may carry diseases. Small, manageable and cute, habitat is contained. Pros and cons
WHAT ARE THE ECOLOGICAL IMPACTS ON INVASIVE SPECIES? • Competition with local species. • Change to ecosystems, in which even a whole food web can change. • Domination of ecosystems by an introduced species is an extreme case. • Disease: invasive species may carry diseases to which native species are not adapted. • Hybridization : introduced species may not be quite genetically separated from a native species, and can then proceed to hybridize. This process may mean the end of a genetically somewhat, but not quite, separated local population.
INVASIVE SPECIES: HOW SERIOUS A PROBLEM ARE THEY? Estimate: costs of invasive species in the United States ~$125-140 billion each year. Estimate: 25% of US agriculture gross national product lost to foreign pests. Nearly half of the species listed as threatened or endangered under the Endangered Species Act are at risk due to competition with or predation by non-native species.
WE CAN THUS CONCLUDE THAT INVASIVE SPECIES ARE: • A major threat to ecosystem health (especially where ecosystems are already impacted) • A major factor in species extinction, especially in tropical climates and on islands • A major threat for global biodiversity, because the transport of species in essence creates one global ecosystem • The cause of major financial damages • Hardly or not limited in spread by international treaties It should also be noted that there is not much support for measures by the 'average citizen' (especially if an invasive animal species is cute, an invasive plant species beautiful), and that the severity of the problem is strongly underestimated.