Scobie A R, Wilcock C C
School of Biological Sciences, University of Aberdeen, Cruickshank Building, St Machar Drive, Aberdeen AB24 3UU, Scotland, UK.
Ann Bot. 2009 Apr;103(6):835-46. doi: 10.1093/aob/mcp007. Epub 2009 Jan 30.
Small populations of rare plant species are increasingly reported to have high levels of reproductive failure. The objective of this study was to understand the principal constraints on sexual reproduction in small fragmented populations of a rare clonal self-incompatible plant.
The pollinator spectrum, diversity of flower colour, natural pollination and fruit-set levels of L. borealis were examined in Scotland. Artificially crossed seed production was compared within and between different flower colour types and patches.
Linnaea borealis was pollinated by a diverse spectrum of insect species and the principal pollinators were muscid, syrphid and empid flies which mostly moved only small distances (<0.25 m) between flowers when foraging. Natural pollination levels were high, indicating high pollinator effectiveness, but fruit set was very low in most patches. Flower colour diversity was low in most patches and only those with a diversity of flower colour types had high fruiting success. Pollination experiments showed L. borealis to be highly self-incompatible and artificial crosses within and between patches and flower colour types confirmed that low fruit success was the result of a lack of compatible mates and limited pollen movement between them. Evidence of isolation from pollen exchange was apparent at as little as 6 m and severe at 30 m and beyond.
Limited mate availability and isolation from pollen exchange compromise the reproductive success of fragmented populations of L. borealis in Scotland. A diversity of compatible mates situated within close proximity (<6 m) is the key requirement to ensure high natural fruiting success. This study emphasizes that an understanding of the breeding system, pollinator spectrum and potential for interconnectivity via pollinator movement are fundamental to identify isolation distances and to establish when conservation intervention is necessary for rare species.
越来越多的报道称，稀有植物物种的小种群存在高水平的繁殖失败。本研究的目的是了解一种稀有的克隆自交不亲和植物的小片段化种群中，有性生殖的主要限制因素。
在苏格兰对北极花的传粉者谱、花色多样性、自然授粉和坐果水平进行了研究。比较了不同花色类型和斑块内及斑块间人工杂交种子的产量。
北极花由多种昆虫传粉，主要传粉者为蝇科、食蚜蝇科和舞虻科的苍蝇，它们在觅食时大多仅在花朵间移动很短的距离（<0.25米）。自然授粉水平较高，表明传粉者效率较高，但大多数斑块中的坐果率很低。大多数斑块中的花色多样性较低，只有那些具有多种花色类型的斑块才有较高的结果成功率。授粉实验表明北极花高度自交不亲和，斑块内及斑块间和花色类型间的人工杂交证实，低结果成功率是由于缺乏相容的配偶以及它们之间有限的花粉传播。在仅6米的距离就明显存在花粉交换隔离的证据，在30米及更远的距离则更为严重。
配偶可用性有限以及与花粉交换隔离，损害了苏格兰北极花片段化种群的繁殖成功率。确保高自然结果成功率的关键要求是在近距离（<6米）内有多种相容的配偶。本研究强调，了解繁殖系统、传粉者谱以及通过传粉者移动实现相互连接的潜力，对于确定隔离距离以及确定何时对稀有物种进行保护干预至关重要。
