Reduced reproductive success and offspring survival in fragmented populations of the forest herb Phyteuma spicatum
Reduced reproductive success and offspring survival in fragmented populations of the forest herb Phyteuma spicatum
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DOI：
10.1111/j.1365-2745.2005.01049.x
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发表时间：
2005-12-01
影响因子：
5.5
通讯作者：
Kolb, A
中科院分区：
文献类型：
--
作者：
Kolb, A
1生境破碎化缩小了种群的规模，增加了种群的隔离，是对生物多样性的一个重大威胁。对于Phyteuma spicatum，一种在德国西北部落叶林中自交不亲和的稀有下层草本植物，我检验了以下假设：（i）健康（就繁殖成功率而言）在小的或孤立的种群中减少，（ii）花粉限制减少了小种群的繁殖;（iii）遗传效应导致小种群的适合度降低。2我比较了14个不同大小和隔离程度的种群中Phyteuma植物的繁殖成功率。种子生产，正如预测的那样，正相关的人口规模，但也受到植物大小的影响，虽然不是由人口隔离，密度或栖息地质量。3我进行了补充手授粉的14个人口中的10个使用花粉从同一人口（花粉量测试）或从另一个大的人口（花粉质量）。人工授粉植物和开放授粉对照之间的种子产量的比例差异随着人口规模的减小而增加，表明传粉者在小人口中的繁殖限制。两种人工授粉处理之间没有差异，表明即使在最小的种群中也有足够数量的杂交亲和配偶。4来自14个种群的后代在共同的环境中生长32周。有发芽人口规模没有影响，但最终幼苗存活率呈正相关的人口规模，这种关系是更明显的温室比在更有利的生长条件下，在一个共同的花园。因此，遗传效应可能会降低小种群植物的适应性（这里以生存率衡量），使它们更容易受到环境胁迫的影响。不同的过程，如花粉限制和遗传退化，可能会相互作用，影响当地人口动态和物种在破碎景观的持久性。
1 Habitat fragmentation, which reduces the size and increases the isolation of populations, is a major threat to biodiversity. For Phyteuma spicatum, a self-incompatible, rare understorey herb in deciduous forests of north-western Germany, I tested the hypotheses that: (i) fitness (in terms of reproductive success) is reduced in small or isolated populations, (ii) reproduction in small populations is reduced by pollen limitation and (iii) genetic effects cause fitness reductions in small populations.2 I compared the reproductive success of plants of Phyteuma in 14 populations of different size and degree of isolation. Seed production was, as predicted, positively related to population size but was also influenced by plant size, although not by population isolation, density or habitat quality.3 I performed supplemental hand-pollinations in 10 of the 14 populations using pollen from the same population (test for pollen quantity) or from another large population (pollen quality). The proportional difference in seed production between hand-pollinated plants and open-pollinated controls increased with decreasing population size, indicating pollinator limitation of reproduction in small populations. There was no difference between the two hand-pollination treatments, suggesting that a sufficient number of cross-compatible mates was available even in the smallest populations.4 Progeny from the 14 populations were grown for 32 weeks in a common environment. There was no effect of population size on germination, but final seedling survival was positively related to population size, and this relationship was more pronounced in the glasshouse than under more favourable growing conditions in a common garden. Genetic effects may thus reduce fitness (here measured in terms of survival) in plants from small populations, making them more susceptible to environmental stress.5 The results suggest that both reproduction and offspring performance may be reduced in small populations even of long-lived species such as Phyteuma spicatum. Different processes, such as pollen limitation and genetic deterioration, may interact and affect local population dynamics and the persistence of species in fragmented landscapes.