PDF(Pubmed)
Abstract：
Harsh, unpredictable environments are known to favor cooperative groups in animals. Whether plants exhibit similar relationships is unknown. Staghorn ferns (Platycerium bifurcatum, Polypodiaceae) are epiphytes that form cooperative groups which build communal water and nutrient \'nests\' at the tops of trees, a habitat characterized by water and nutrient stress. We conducted field observations to test whether staghorn ferns continue to live in large, reproductively active groups after they become dislodged from the canopy and fall to the forest floor, where they are less limited by water and nutrient deprivation. To rule out the potentially confounding effects of light limitation on the forest floor, we also conducted a multi-year glasshouse experiment where we transplanted individual plants into soil and onto vertically oriented boards under standardized light conditions. Results from field observations showed that dislodged colonies formed smaller groups that reproduced less than epiphytic colonies. Results from the glasshouse experiment showed that even when growing in full sun, terrestrial individuals tended to remain solitary, while epiphytic individuals tended to recruit new individuals into colonies. Results also showed that plants growing in potting soil and exposed to full sunlight sporulated more heavily than plants growing epiphytically. However, localities that are characterized by both elevated soil and light resources are generally not available to staghorn ferns in the wild, perhaps with the exception of large, epiphytic colonies with well-developed nests at the top of tree canopies. Overall results indicate that the harsh environmental conditions at the tops of trees trigger the formation of colonies in staghorn ferns, similarly to group living animals.
摘要：
严厉，已知不可预测的环境有利于动物中的合作团体。植物是否表现出相似的关系是未知的。鹿角蕨类植物（桔梗，Polypadiaceae）是形成合作群体的附生植物，它们在树木的顶部建立公共水和营养“巢”，以水和营养压力为特征的栖息地。我们进行了实地观察，以测试鹿角蕨类植物是否继续生活在大，繁殖活跃的群体在从树冠脱落并落入森林地面后，它们受到水和营养匮乏的限制较少。为了排除光限制对森林地面的潜在混杂影响，我们还进行了一项为期多年的温室实验，在标准光照条件下，我们将单个植物移植到土壤和垂直方向的板上。野外观察的结果表明，移位的菌落形成了较小的群体，其繁殖量小于附生菌落。温室实验的结果表明，即使在阳光下生长，陆地个体倾向于保持孤独，而附生个体倾向于招募新个体进入殖民地。结果还表明，在盆栽土壤中生长并暴露于阳光下的植物比附生生长的植物孢子更多。然而,具有高土壤和光照资源特征的地区通常无法在野外使用鹿角蕨类植物，也许除了大型的，在树冠顶部有发育良好的巢的附生菌落。总体结果表明，树顶的恶劣环境条件触发了鹿角蕨类植物菌落的形成，类似于群居动物。
