Abstract A reintroduction attempt of Eriocaulon heleocharioides Satake (Eriocaulaceae)—an annual amphibious herb species that is extinct in the wild—has been conducted in its last natural habitat from 2009. Unfortunately, this in-situ conservation measure has failed, probably due to environmental and genetic constraints related to long-term ex-situ cultivation. To evaluate the ex-situ conserved population and elucidate the factors impeding in-situ conservation, we investigated environmental and reproductive effects on life history traits to support appropriate conservation management strategies. First, we performed open outcross-pollination and self-pollination to verify the levels of reproductive success associated to the blooming sequence of the inflorescences (1 st to 6th inflorescences). Subsequently, growth experiments incorporating the maternal effect were conducted using inbred and outbred offspring under different environmental conditions (underwater and wet-soil). Based on hierarchical Bayesian models, we compared the effects of outcross-pollination and self-pollination on reproductive outputs and fitness traits. Analysis of the overall trend suggested that outcross-pollination significantly decreased the reproductive output, and negative effects were more pronounced in the first and in the last inflorescence. Regarding reproductive fitness, outcross-pollination was significantly correlated with greater seed mass. Post-germination, the growth of the outbred offspring was superior to that of the inbred offspring in approximately 30–40 % of the mother plants. Regarding the number of inflorescences and maximum leaf length, the overall negative effects of outcross-pollination increased with time. Outcross-pollination showed a significant positive effect on the survival rate in underwater conditions, whereas a negative effect was detected in wet-soil conditions. E. heleocharioides has a preference for self-pollination according to the pollen-ovule ratio. Increase of negative effects of outcross-pollination with time may suggest the genetic unhealthiness of E. heleocharioides. Inbreeding depression was lower under captivity, possibly reflecting adaptation to ex situ conditions (i.e., wet soil). This may have impeded a successful establishment of E. heleocharioides in the reintroduction site, because it was characterized by a higher water depth. In contrast, introducing underwater cultivation in the captive site could limit the spread of inbred individuals, by contributing to reduce the adaptation to ex situ conditions. To ensure the success of in-situ conservation, the use of appropriate environmental condition and lineages in which the mother plants exhibit low extent of inbreeding depression is required.

中文翻译：

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重新引入 Eriocaulon heleocharioides（Eriocaulaceae）的生物和生态限制：一种在野外灭绝的物种

摘要 从 2009 年开始，在其最后一个自然栖息地中重新引入 Eriocaulon heleocarioides Satake (Eriocaulaceae)——一种在野外灭绝的一年生两栖草本植物。不幸的是，这种就地保护措施失败了，可能是由于环境和与长期异地种植相关的遗传限制。为了评估异地保护种群并阐明阻碍就地保护的因素，我们调查了环境和繁殖对生活史特征的影响，以支持适当的保护管理策略。首先，我们进行了开放异花授粉和自花授粉，以验证与花序（第 1 至第 6 花序）开花顺序相关的繁殖成功水平。随后，在不同环境条件（水下和湿土）下，使用近交和远交后代进行了结合母体效应的生长实验。基于分层贝叶斯模型，我们比较了异花授粉和自花授粉对生殖输出和健康性状的影响。总体趋势分析表明，异花授粉显着降低了生殖产量，并且在第一个和最后一个花序中的负面影响更为明显。关于生殖适应性，异花授粉与更大的种子质量显着相关。发芽后，在大约 30-40% 的母株中，远交后代的生长优于近交后代的生长。关于花序数和最大叶长，异花授粉的总体负面影响随着时间的推移而增加。异花授粉在水下条件下对存活率显示出显着的积极影响，而在湿土条件下则检测到负面影响。E. heleocarioides 根据花粉 - 胚珠比率具有自花授粉的偏好。随着时间的推移异花授粉的负面影响增加可能表明 E. heleocarioides 的遗传不健康。圈养条件下近交衰退较低，可能反映了对异地条件（即潮湿土壤）的适应。这可能阻碍了在重新引入地点成功建立 E. heleocarioides，因为它的特点是水深较高。相比之下，在圈养地点引入水下养殖可以限制近交个体的传播，有助于减少对异地条件的适应。为了确保就地保护的成功，需要使用适当的环境条件和母株近交衰退程度较低的谱系。