CONICET | Buscador de Institutos y Recursos Humanos

Although isolated records of nonindigenous species (i.e., species transported with the aid of human activities outside of their native geographic ranges) have been known for centuries, the first comprehensive work on these organisms and their impacts is the book by Charles Elton published in 1958. The rate of species introductions increased significantly since the middle XIX century, with recent estimates suggesting around 600 plant and animal species per year. Many of these introductions have been deliberate (crops and ornamental plants, domesticated and wild animals), but most were accidental, usually in association with the intra- and intercontinental transport, chiefly by sea, of people and merchandise. Some of these species have been very successful in colonizing the new habitats and became invasive, displacing native species and affecting resident communities and human interests. As a consequence of these high-profile invasions, in the last 30 years or so a new ecological discipline flourished - ?Invasion Biology?. Among its goals are attempts at establishing hypotheses or general rules aimed at explaining how and why some introduced species are so successful in the areas they colonized. However, empirical support for these hypotheses has been very uneven: each explains some cases, but fails to account for many others. Invasion Biology is presently moving on thin ice, unable to reach consensus on such elementary notions as differences between native, introduced, and invasive. Idiosyncratic conservation-related issues, as well as legitimate and personal interest-driven academic and social factors led to the demonization of introduced species engendering a deep crevice in the field. A majority of the scholars in this young field adhered to the concept that geographic origin is of utmost importance: all introduced species are undesirable, and therefore guilty of negative impacts until proven innocent. In contrast, other researchers consider that geographic origin is of minor importance; like many indigenous species, most introduced organisms have negative impacts on some natives, positive on others, and mostly neutral impacts overall. The pristine state of ecosystems, free from introduced species, is a subjective human concept strongly influenced by emotional, ideological and cultural values fostered by conservationists. Both introduced and native species can have undesirable impacts on ecosystems and on human interests, and these impacts depend on multiple factors, especially the species concerned, but also many other conditions associated with functional roles, time, and space. When the overall impacts are clearly negative, both native and introduced species may require human intervention in the form of control or eradication actions, regardless of their geographic origin.

enviar mensaje