Abstract

Clarifying the conditions in which a species can germinate helps elucidate dispersal and establishment patterns. Conventionally considered a freshwater species, evidence indicates that the invasive Yellow flag iris (Iris pseudacorus), originally from North Africa, East Asia and Europe, tolerates saline conditions. Clarifying how water-dispersed I. pseudacorus seeds respond to seawater immersion is critical to understanding marine dispersal and invasion risk for coastal habitats. Accordingly, we evaluated the impact of salinity on the germination of I. pseudacorus. Using seeds from marine and freshwater I. pseudacorus populations, we assessed how the duration of immersion (15, 30, 60, and 90 days) in varying salinities (0, 13–15, 33–35 practical salinity units [PSU]) affected germination, and whether immersion in freshwater following saline exposure impacted germination or seed viability. Seeds sourced from freshwater consistently outperformed seeds from the marine population. Neither salinity concentration nor immersion duration had a statistically significant impact on germination, and nearly all seeds remained buoyant in marine saltwater (33–35 PSU) for 90 days. Saline immersion and germination conditions inhibited germination unless seeds received a freshwater recovery. The freshwater population of seeds had statistically significantly thicker seed coats, but there was no discernible difference in mean seed weight. Seeds from both populations remained viable after prolonged salinity exposure (90–165 days). We posit that observed differences in germination between the two populations may arise from seed dormancy mechanisms rather than seed fitness. Our results suggest that I. pseudacorus seeds could disperse vast distances through the marine environment, possibly habitat-hopping to reach increasingly suitable ecosystems.

中文翻译：

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淡水入侵鸢尾花对咸水和海洋盐度的萌发反应以及对沿海入侵的影响

摘要

阐明物种发芽的条件有助于阐明其扩散和定居模式。传统上被认为是淡水物种，有证据表明，来自北非、东亚和欧洲的入侵性黄旗鸢尾（Iris pseudacorus ）能够耐受盐水环境。阐明水传播的I. pseudacorus种子如何响应海水浸泡对于了解沿海栖息地的海洋传播和入侵风险至关重要。因此，我们评估了盐度对 I. pseudacorus 发芽的影响。使用来自海洋和淡水I. pseudacorus种群的种子，我们评估了不同盐度（0、13–15、33–35 实际盐度单位 [PSU]）中浸泡持续时间（15、30、60 和 90 天）的影响发芽，以及盐水暴露后浸泡在淡水中是否影响发芽或种子活力。来自淡水的种子始终优于来自海洋的种子。盐度浓度和浸泡时间对发芽没有统计学上的显着影响，几乎所有种子在海水 (33-35 PSU) 中都能保持浮力 90 天。除非种子接受淡水恢复，否则盐水浸泡和发芽条件会抑制发芽。淡水种子群体的种皮在统计上显着更厚，但平均种子重量没有明显差异。两个种群的种子在长期暴露于盐分（90-165 天）后仍然保持活力。我们假设观察到的两个群体之间发芽的差异可能源于种子休眠机制而不是种子适应性。我们的结果表明，I. pseudacorus种子可以在海洋环境中传播很远的距离，可能会跨越栖息地到达越来越适合的生态系统。