Variation in Sexual Expression in Jacaratia mexicana (Caricaceae) in Southern Mexico: Frequency and Relative Seed Performance of Fruit‐Producing Males
Variation in Sexual Expression in Jacaratia mexicana (Caricaceae) in Southern Mexico: Frequency and Relative Seed Performance of Fruit‐Producing Males
复制标题
墨西哥南部 Jacaratia mexicana（Caricaceae）性表达的变异：产果雄性的频率和相对种子性能
DOI：
10.1111/j.1744-7429.2006.00230.x
复制
发表时间：
2007
期刊：
影响因子：
2.1
通讯作者：
R. Dirzo
中科院分区：
文献类型：
--
作者：
A. Aguirre;M. Vallejo‐Marín;Lizandra Salazar;D. Arias;R. Dirzo
雌雄异体，即个体之间雄性和雌性结构的分离，在热带植物中广泛存在，在某些地区涵盖了 10-30% 的物种。在许多情况下，个体间的性别分离并不完全，因为个体植物虽然名义上是雌雄异株的，但可能产生两种类型的生殖结构。这种性别变异的常见形式是在雄性个体中产生雌性结构，通常称为结果雄性。在这里，我们报道了雌雄异体的热带树雅卡拉蒂亚墨西哥（Caricaceae）中存在结果雄性。我们发现，在墨西哥南部热带森林的某些种群中，结果雄性可占所有雄性的 45%。为了确定结果雄性对于墨西哥果树育种系统的功能意义，我们比较了雄性和雌性种子的相对性能。我们的结果表明，结果的雄性树的种子发芽和存活的可能性是雌性树的种子的三倍。根据相对种子适应性数据和自然种群中的性别比例，我们估计，结果雄性向下一代贡献的基因中有 6-15% 通过胚珠传递，这意味着性别的形态变异至少部分伴随着功能性性别变异。最后，我们对结果雄性植物的种子适应性估计表明，结果雄性植物不会取代自然种群中的雌性植物。
Dioecy, the segregation of male and female structures among individuals, is widespread in tropical plants, encompassing 10–30 percent of species in some sites. In many cases, interindividual sex separation is not complete, as individual plants, although nominally dioecious, may produce both types of reproductive structures. A common form of this sexual variation is the production of female structures in otherwise male individuals, commonly referred to as fruiting males. Here we report the existence of fruiting males in the dioecious tropical tree Jacaratia mexicana (Caricaceae). We show that fruiting males can constitute up to 45 percent of all males in some populations of a tropical forest in Southern Mexico. In order to determine the functional significance of fruiting males for the breeding system of J. mexicana, we compared the relative performance of male‐ and female‐borne seeds. Our results show that seeds from fruiting males are three times less likely to germinate and survive than seeds from female trees. Based on relative seed fitness data, and sex ratios in natural populations, we estimate that 6–15 percent of the genes contributed by fruiting males to the next generation are transmitted via ovules, meaning that morphological variation in gender is at least partially accompanied by functional gender variation. Finally, our seed fitness estimates for fruiting males suggest that fruiting males will not replace female plants in natural populations.