Evolutionary and physiological adaptations of aquatic invasive animals: r selection versus resistance

Abstract

Invasive species have been characterized as tolerant of environmental extremes. This hypothesis was evaluated for invasive aquatic species in North America, particularly Asian clams, Corbicula fluminea, and zebra mussels, Dreissena polymorpha. Both species have rapid growth, early maturity, short life spans, and elevated fecundity, allowing rapid population recovery after reductions by rarefractive, environmental extremes. Extensive resistance capacities offer little adaptive value to invasive, r-selected species, because population reductions occur in their unstable habitats regardless of degree of stress tolerance. Thus, both species have relatively poor physiologic resistance, depending instead on elevated growth and fecundity for rapid population recovery. In contrast, native North American bivalve species are often adapted to stable habitats where perturbation is infrequent (i.e., freshwater unionoidean bivalves). They are characterized by slow growth, extended life spans, and low effective fecundities, slowing population recoveries (K-selected), and have evolved extensive resistance adaptations to avoid extirpation during environmental extremes. Review of resistance adaptations in other North American aquatic invaders revealed poorer or equivalent physiological tolerance relative to taxonomically related native species, suggesting that extensive physiological tolerance is not required for invasive success.

Estuarine consumers utilize marine, estuarine and terrestrial organic matter and provide connectivity among these food webs

“…watershed inputs, river water chemistry) (Fry 2002, Fry & Allen 2003. The same is likely true for C. fluminea owing to its rapid growth rate and similarly short life span (McMahon 2002, Thompson & Parchaso 2010.…”

Ecology of the invasive Asian clam Corbicula fluminea (Müller, 1774) in aquatic ecosystems: an overview

“…The invasive success and subsequent dispersion of C. fluminea relies more on their natural (2) characteristics (e.g. rapid growth, earlier sexual maturity, short life span, high fecundity, extensive dispersal capacities and its association with human activities) than in its physiological tolerance (McMahon 2002). In fact, this NIS when compared, for example, with other freshwater bivalve species appears to be less tolerant to environmental fluctuations such as elevated temperatures, hypoxia, emersion, low pH and low calcium concentrations (Byrne & McMahon 1994, McMahon 2000, Johnson & McMahon 1998, McMahon & Bogan 2001, Sousa et al 2007b.…”

The American brine shrimp as an exotic invasive species in the western Mediterranean

“…According to Ehrlich (1984), Lodge (1993) and McMahon (2002), successful invasive species usually display different degrees of the following attributes: (1) abundance in their original range or large native range, (2) polyphagous or eurytrophic (i.e. wide feeding niche), (3) much genetic variability or phenotypic plasticity, (4) short generation times, (5) fertilized females able to colonize alone (i.e.…”

“…It has been argued that there is little evidence suggesting that physiological capacity to tolerate and function in a wide range of physical conditions is a prerequisite to successful invasions of aquatic habitats (McMahon 2002). In the genus Artemia, although the information on the tolerance of its different species to a wide range of physical conditions is not complete, it is commonly accepted that its adaptation to the severe habitats of hypersaline ecosystems, and its wide distribution in all continents except Antarctica, mean that the species and populations can withstand the widest salinity and temperature ranges among aquatic organisms, living in salinities at or below seawater concentration (35 g l )1 ), up to saturation level (300 g l )1 ).…”