Wilsey Brian J, Barber Kaitlin, Martin Leanne M
Department of Ecology, Evolution and Organismal Biology, 253 Bessey Hall, Ames, IA, 50011, USA.
New Phytol. 2015 Jan;205(2):928-37. doi: 10.1111/nph.13028. Epub 2014 Sep 23.
During community assembly, early arriving exotic species might suppress other species to a greater extent than do native species. Because most exotics were intentionally introduced, we hypothesize there was human selection on regeneration traits during introduction. This could have occurred at the across- or within-species level (e.g. during cultivar development). We tested these predictions by seeding a single species that was either native, exotic 'wild-type' (from their native range), or exotic 'cultivated' using 28 grassland species in a glasshouse experiment. Priority effects were assessed by measuring species' effect on establishment of species from a seed mix added 21 d later. Exotic species had higher germination and earlier emergence dates than native species, and differences were found in both 'wild' and 'cultivated' exotics. Exotic species reduced biomass and species diversity of later arriving species much more than native species, regardless of seed source. Results indicate that in situations in which priority effects are likely to be strong, effects will be greater when an exotic species arrives first than when a native species arrives first; and this difference is not merely a result of exotic species cultivation, but might be a general native-exotic difference that deserves further study.
在群落组装过程中，早期到达的外来物种可能比本地物种更能抑制其他物种。由于大多数外来物种是有意引入的，我们推测在引入过程中对再生性状存在人为选择。这可能发生在物种间或物种内水平（例如在品种培育过程中）。我们通过在温室实验中用28种草种播种单一物种来检验这些预测，这些物种分别是本地物种、外来“野生型”（来自其原生范围）或外来“栽培型”。通过测量物种对21天后添加的种子混合物中物种建立的影响来评估优先效应。外来物种比本地物种具有更高的发芽率和更早的出苗日期，并且在“野生”和“栽培”外来物种中均发现了差异。无论种子来源如何，外来物种比本地物种更能降低后期到达物种的生物量和物种多样性。结果表明，在优先效应可能很强的情况下，外来物种先到达时的影响将比本地物种先到达时更大；这种差异不仅仅是外来物种栽培的结果，而是可能是一种值得进一步研究的普遍的本地 - 外来差异。
