Habitat niche breadth predicts invasiveness in solitary ascidians

Abstract

A major focus of invasion biology is understanding the traits associated with introduction success. Most studies assess these traits in the invaded region, while only few compare nonindigenous species to the pool of potential invaders in their native region. We focused on the niche breadth hypothesis, commonly evoked but seldom tested, which states that generalist species are more likely to become introduced as they are capable of thriving under a wide set of conditions. Based on the massive introduction of tropical species into the Mediterranean via the Suez Canal (Lessepsian migration), we defined ascidians in the Red Sea as the pool of potential invaders. We constructed unique settlement plates, each representing six different niches, to assess ascidian niche breadth, and deployed them in similar habitats in the native and invaded regions. For each species found on plates, we evaluated its abundance, relative abundance across successional stages, and niche breadth, and then compared (1) species in the Red Sea known to have been introduced into the Mediterranean (Lessepsian species) and those not known from the Mediterranean (non‐Lessepsian); and (2) nonindigenous and indigenous species in the Mediterranean. Lessepsian species identified on plates in the Red Sea demonstrated wider niche breadth than non‐Lessepsian species, supporting the niche breadth hypothesis within the native region. No differences were found between Lessepsian and non‐Lessepsian species in species abundance and successional stages. In the Mediterranean, nonindigenous species numerically dominated the settlement plates. This precluded robust comparisons of niche breadth between nonindigenous and indigenous species in the invaded region. In conclusion, using Red Sea ascidians as the pool of potential invaders, we found clear evidence supporting the niche breadth hypothesis in the native region. We suggest that such patterns may often be obscured when conducting trait‐based studies in the invaded regions alone. Our findings indicate that quantifying the niche breadth of species in their native regions will improve estimates of invasiveness potential.

Borrelia bavariensis: Vector Switch, Niche Invasion, and Geographical Spread of a Tick-Borne Bacterial Parasite

“…The hypothesis that a "broader" niche allows the organism to display a more extensive set of adaptations to varying ecological conditions, so that a larger geographic area will be potentially available to it (Slatyer et al, 2013). The idea that invasiveness is correlated with overall "niche breadth" can be tested at a simple level; the hypothesis is not universally validated by evidence but has received strong support in some cases (e.g., Sol, 2016;Granot et al, 2017). Unfortunately, however, it is not self-evident what is meant by overall "niche breadth" nor how it can be measured or compared.…”

Supplementary material 3 from: Bustamante RO, Alves L, Goncalves E, Duarte M, Herrera I (2020) A classification system for predicting invasiveness using climatic niche traits and global distribution models: application to alien plant species in Chile. NeoBiota 63: 127-146. https://doi.org/10.3897/neobiota.63.50049

“…Climatic niche breadth has frequently been used to predict invasiveness ("niche breadth-invasion success hypothesis") (Granot et al 2017;Vazquez 2006). Similar results have also been obtained for native plants, where climatic niche traits are good predictors of the biogeographic expansion of native trees (Vela Díaz et al 2020).…”

Spatial Variability in a Symbiont-Diverse Marine Host and the Use of Observational Data to Assess Ecological Interactions

“…This ascidian is a common member of fouling communities around the world and recruits year-round, although it is more common at early successional community stages [32,36,37]. Population densities can fluctuate seasonally by an order of magnitude [32,38] and surpass 100/m 2 within native and invaded ranges, with the highest recruitment densities recorded reaching > 500/m 2 in the Red Sea [38][39][40].…”