Reproductive output of invasive versus native plants

Abstract

Aim Propagule size and output are critical for the ability of a plant species to colonize new environments. If invasive species have a greater reproductive output than native species (via more and/or larger seeds), then they will have a greater dispersal and establishment ability. Previous comparisons within plant genera, families or environments have conflicted over the differences in reproductive traits between native and invasive species. We went beyond a genus-, family-or habitat-specific approach and analysed data for plant reproductive traits from the global literature, to investigate whether: (1) seed mass and production differ between the original and introduced ranges of invasive species; (2) seed mass and production differ between invasives and natives; and (3) invasives produce more seeds per unit seed mass than natives.Location Global. MethodsWe combined an existing data set of native plant reproductive data with a new data compilation for invasive species. We used t -tests to compare original and introduced range populations, two-way ANOVAs to compare natives and invasives, and an ANCOVA to examine the relationship between seed mass and production for natives and invasives. The ANCOVA was performed again incorporating phylogenetically independent contrasts to overcome any phylogenetic bias in the data sets. ResultsNeither seed mass nor seed production of invasive species differed between their introduced and original ranges. We found no significant difference in seed mass between invasives and natives after growth form had been accounted for. Seed production was greater for invasive species overall and within herb and woody growth forms. For a given seed mass, invasive species produced 6.7-fold (all species), 6.9-fold (herbs only) and 26.1-fold (woody species only) more seeds per individual per year than native species. The phylogenetic ANCOVA verified that this trend did not appear to be influenced by phylogenetic bias within either data set. Main conclusionsThis study provides the first global examination of both seed mass and production traits in native and invasive species. Invasive species express a strategy of greater seed production both overall and per unit seed mass compared with natives. The consequent increased likelihood of establishment from longdistance seed dispersal may significantly contribute to the invasiveness of many exotic species.

A test of baker’s law: breeding systems of invasive species of Asteraceae in China

“…Obviously, introduced alien species can only become invasive if they manage to reproduce (Richardson et al 2000). Indeed, high fecundity is frequently associated with invasive alien plant species (Pyšek and Richardson 2007;Mason et al 2008;van Kleunen et al 2010). However, it is less clear how invasive alien plants achieve a high reproductive output, particularly because they may lack suitable pollinators and/or suitable mates in the new range.…”

Floral biology and breeding system of Impatiens balfourii (Balsaminaceae): An exotic species in extension in temperate areas

“…Even if some invasive plants reproduce only asexually, many cases of high seed sets have been reported for aliens (Mason et al, 2008), e.g., Heracleum mantegazzianum (more than 20,000 seeds per plant, Perglová et al, 2006). Higher seed set for the invasive was reported in comparative studies between invasive and native congeners (Mason et al, 2008).…”

“…Invasive plants often show conspicuous visual attractants and floral rewards, such as pollen and nectar of high quantities and qualities (Rejmánek, 2000;Vervoort et al, 2011). Furthermore, some of them extend their reproductive season and produce high seed numbers per individual (Rejmánek and Richardson, 1996;Mason et al, 2008;Torres et al, 2013). All those traits have never been studied for Impatiens balfourii.…”

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“…Regarding the introduction of a new species into a native food web, there are a series of niche-based hypotheses that potentially explain how the introduced species integrates into the community and how native species can coexist in sympatry with the invader (Ricciardi, Hoopes, Marchetti & Lockwood, 2013). For example, the release of a new species into a species-poor community that has unexploited resources would enable the invader to utilise these resources, avoiding competitive interactions with native species and enhancing their ability to integrate into the food web (Mason, Cooke, Moles & Leishman, 2008;Juncos, Milano, Macchi & Vigliano, 2015). When the introduction is into a community where resources are fully exploited and potentially limiting, theory predicts that the interactions between the introduced and native species will result in both their trophic niches becoming constricted and divergent through dietary specialisms (Bolnick et al, 2010;Tran, Jackson, Sheath, Verreycken & Britton, 2015;Jackson, Grey, Miller, Britton, & Donohue, 2016).…”