Effects of forest fragmentation and flowering phenology on the reproductive success and mating patterns of the tropical dry forest tree Pachira quinata
Effects of forest fragmentation and flowering phenology on the reproductive success and mating patterns of the tropical dry forest tree Pachira quinata
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DOI：
10.1046/j.1523-1739.2003.01140.x
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发表时间：
2003-02-01
影响因子：
6.3
通讯作者：
Quesada, M
中科院分区：
文献类型：
--
作者：
Fuchs, EJ;Lobo, JA;Quesada, M
几项研究的结果表明，森林片断化通过减少传粉者活动、花粉沉积和异交水平影响热带树种的交配模式和繁殖成功。树木的开花同步性也被认为是控制坐果和调节异交水平的一个额外因素，特别是在受干扰的生境中。我们研究了森林片断化和开花物候对热带树木Pachira quinata产生的后代的繁殖成功率和遗传结构的影响。我们在哥斯达黎加的干燥森林中进行了研究，并在两种密度和环境条件下对树木进行了比较：（1）与其他成年同种种相隔500 m并位于干扰地点的孤立树木;（2）被未受干扰的成熟森林包围的每公顷20个或更多繁殖个体的连续种群的树木。我们的研究是在瓜纳卡斯特保护区，哥斯达黎加，和周边地区。为了评估开花物候，树木被分类为具有同步或异步开花。个体的物候期根据每棵树的开花高峰期与其余种群的平均开花高峰期的接近程度进行分类。在连续种群的树木中，6%的花结出果实，而在孤立的树木中，只有3%的花结出果实。坐果不受树木开花物候的影响，但主要是与森林破碎化的因素。每果种子产量不受森林破碎化或开花物候。总体而言，每棵树的水果总产量不受森林破碎化的影响，因为孤立的树木往往比连续种群的树木产生更多的花朵。遗传分析表明，后代的树木从连续的人口经历了较低水平的相关性，更高水平的异交的倾向，和/或更多的父亲比孤立的树木。我们的研究结果表明，森林片断化可以有一个影响的交配模式的P. quinata，减少了数量的异交公畜代表的后代孤立的树木。
The results of several studies suggest that forest fragmentation affects the mating patterns and reproductive success of tropical tree species by reducing pollinator activity, pollen deposition, and outcrossing levels. The flowering synchrony of trees has also been proposed as an additional factor in controlling fruit set and regulating levels of outcrossing, particularly in disturbed habitats. We examined the effects of forest fragmentation and flowering phenology on the reproductive success and genetic structure of the progeny produced by the tropical tree Pachira quinata . We conducted our study in the dry forest of Costa Rica and compared trees in two density and environmental conditions: ( 1 ) isolated trees separated by 500 m from other adult conspecifics and located in disturbed sites and ( 2 ) trees from continuous populations of groups of 20 or more reproductive individuals per hectare surrounded by undisturbed mature forest. Our study was conducted in the Guanacaste Conservation Area, Costa Rica, and surrounding areas. To evaluate flowering phenology, trees were classified as having synchronous or asynchronous flowering. The phenological stage of individuals was classified according to the proximity of the peak flowering date of each tree with respect to the mean peak flowering of the rest of the population. Six percent of the flowers produced a fruit in trees from continuous populations, whereas in isolated trees only 3% of the flowers did so. Fruit set was not affected by the flowering phenology of trees but was influenced mainly by factors associated with forest fragmentation. Seed production per fruit was not affected by forest fragmentation or flowering phenology. Overall, total fruit production per tree was not affected by forest fragmentation, because isolated trees tended to produce more flowers than trees from continuous populations. Genetic analysis revealed that the progeny of trees from continuous populations experienced lower levels of relatedness, a tendency for higher levels of outcrossing, and/or more sires than isolated trees. Our results suggest that forest fragmentation can have an effect on the mating patterns of P. quinata , reducing the number of outcross sires represented in the progeny of isolated trees.