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首页> 外文期刊>Conservation Biology >Effects of dry tropical forest fragmentation on the reproductive success and genetic structure of the tree Samanea saman
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Effects of dry tropical forest fragmentation on the reproductive success and genetic structure of the tree Samanea saman

机译：干旱热带森林破碎化对萨曼树萨曼树繁殖成功和遗传结构的影响

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Tropical trees are particularly vulnerable to forest fragmentation it because of their low densities, self-incompatibilty system, and high rates of outbreeding. Forest fragmentation is likely to decrease gene flow, increase endogamy, and eventually produce a high differentiation among remnant populations. Our objectives were to evaluate the effect of forest fragmentation on the reproductive success, progeny vigor, and genetic variation of the tropical dry-forest tree Samanea saman We conducted our study in the dry forest of Costa Rica and compared two tree conditions to evaluate forest fragmentation: (1) isolated, individual trees more than 500 m from the nearest conspecific and surrounded by agricultural fields, pastures, or small remnant forest patches and (2) trees in continuous populations of 10 or more individuals per hectare and surrounded by undisturbed forest, We compared the probability of natural pollination, seed production, genetic variation, and progeny vigor of trees in isolation and in continuous populations. The probability of flowers receiving more than 23 pollen tubes at the base of styles (the flowers more likely to produce a mature fruit) was significantly greater for trees in continuous populations (2.1%) than for trees in isolation (0.4%). However, flowers from the two tree conditions received similar pollen loads on their stigmas. Fruits of trees from continuous populations produced similar numbers of seeds as isolated trees did and had a similar probability of seed predation by brucbid beetles was significantly greater in continuous seed abortion. The probability populations (30%) than in isolated trees (20%). The number of undamaged seeds (potentially viable) was similar for both tree conditions. A genetic analysis of progeny showed that levels of genetic diversity in trees in isolation and in continuous populations were comparable. The effective self-fertilization rate and inbreeding coefficient of the progeny were slightly higher for isolated trees than for trees in continuous populations. In addition, there was more genetic similarity in the progeny of isolated trees, within and between fruits. Seeds produced by different fruits within a tree were more likely to be related in an isolated tree than in a tree from continuous populations. Seeds produced by trees from continuous populations were more likely to germinate and to produce greater leaf area and biomass as seedlings than progeny from isolated trees. We concluded that the fragmentation of tropical dry forests affects the genetic variation and vigor of S. saman progeny. Isolated trees showed high reproductive capacity, however, in spite of their habitat condition. [References: 66]
机译：热带树木由于其密度低，自交不亲和系统和高繁殖率而特别容易受到森林破碎的影响。森林碎片化可能会减少基因流量，增加内婚作用，并最终在剩余种群之间产生高度分化。我们的目标是评估森林破碎对热带旱林树Samanea saman的繁殖成功，后代活力和遗传变异的影响。我们在哥斯达黎加的干旱森林中进行了研究，并比较了两种树木条件以评估森林破碎：（1）离最近同种树500 m以上且被农田，牧场或小片残留森林包围的孤立的个体树木;以及（2）连续人口每公顷10或更多的树木，并被未受干扰的森林包围，我们比较了孤立和连续种群中树木自然授粉，种子生产，遗传变异和后代活力的可能性。在连续种群中，花朵接受样式超过23个的花粉管（花朵更有可能产生成熟果实）的概率显着高于连续种群中的树木（2.1％），而相比之下，孤立的树木（0.4％）更高。但是，两棵树条件下的花在其柱头上受到相似的花粉负荷。来自连续种群的树木的果实产生的种子数量与孤立树木的相似，并且在连续种子流产中，通过硬壳甲虫捕食种子的可能性也明显更高。概率种群（30％）比孤立树（20％）大。两种树木条件下未损坏的种子数量（可能有生命）相似。对后代的遗传分析表明，孤立的树木和连续种群的树木遗传多样性水平相当。后代树木的有效自体受精率和近交系数略高于连续种群中的树木。另外，在果实内和果实之间的孤立树的后代具有更多的遗传相似性。一棵树上不同果实所产生的种子在孤立的树中比在连续种群的树中更可能相关。与来自孤立树木的后代相比，来自连续种群的树木产生的种子更容易发芽，并产生更大的叶面积和生物量作为幼苗。我们得出的结论是，热带干燥森林的碎片化影响萨曼萨曼人后代的遗传变异和活力。隔离的树木尽管具有栖息地条件，但仍具有较高的繁殖能力。 [参考：66]

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