A comparison of invasive and non‐invasive dayflowers (Commelinaceae) across experimental nutrient and water gradients

Abstract

Little is known about the traits and mechanisms that determine whether or not a species will be invasive. Invasive species are those that establish and spread after being introduced to a novel habitat. A number of previous studies have attempted to correlate specific plant traits with invasiveness. However, many such studies may be flawed because they fail to account for shared evolutionary history or fail to measure performance directly. It is also clear that performance is context dependent. Thus, an approach that corrects for relatedness and incorporates multiple experimental conditions will provide additional information on performance traits of invasive species. I use this approach with two or three pairs of invasive and closely related non‐invasive species of Commelinaceae grown over experimental gradients of nutrient and water availability. Invasive species have been introduced, established, and spread outside their native range; non‐invasive species have been introduced, possibly (but not necessarily) established, but are not known to have spread outside their native range. The invasive species had higher relative growth rates (RGR) than non‐invasive congeners at high nutrient availabilities, but did not differ from non‐invasive species at low nutrient availabilities. This is consistent with a strategy where these particular invasive species are able to rapidly use available resources. Relative growth rates were also higher for two out of three invasive species across a water availability gradient, but RGR did not differ in plasticity between the invasive and non‐invasive species. This suggests that nutrient addition, but not changes in water availability, might favour invasion of dayflowers. This approach is novel in comparing multiple pairs of invasive and non‐invasive congeners across multiple experimental conditions and allows evaluation of the robustness of performance differences. It also controls for some of the effects of relatedness that might confound multispecies comparisons.

Relationship between fragmentation, degradation and native and exotic species richness in an Andean temperate forest of Chile

“…By contrast, it was clear that exotic species were positively correlated with degradation, suggesting that exotic species may react faster than native ones to anthropic disturbances (e.g. Hobbs 2001, Burns 2004). The positive correlation between number of livestock faeces and exotic species richness suggests that cattle plays a role in both degrading the sites and aiding arrival/colonization of exotic species (Hobbs 2001, Brothers & Spingarn 1992, D'Antonio 1993.…”

Predicting naturalization of southern African Iridaceae in other regions

“…Most of the few existing studies involve comparisons between naturalized and non-naturalized introduced species in their introduced range (Richardson, van Wilgen & Mitchell 1987;Rejmánek & Richardson 1996;Reichard & Hamilton 1997;Mihulka, Py ß ek & Martínková 2003;Burns 2004). However, to address the ultimate challenge of identifying determinants of naturalization that can be assessed before introduction elsewhere, large-scale studies are required that compare naturalized and non-naturalized species in their common native range (Py ß ek, Richardson & Williamson 2004).…”

Preliminary study on the influence of water level on the growth and morphology ofLimnocharis flava(L.) Buchenau

“…L. flava invasion in agricultural wetlands exists as a mono-species colonization which covers the whole area with time, outcompeting other species available in the area. Usually, invasive alien species are more tolerant to environmental stresses than the native species (Burns, 2004;Zhang and Wen, 2009) and show greater phenotypic plasticity compared with the native species (Davidson et al, 2011). L. flava rapidly spreads in wetlands and agricultural wetlands.…”