Department of Ecology, Evolution and Natural Resources, Rutgers University, New Brunswick, NJ, USA.
J Hered. 2010 Mar-Apr;101(2):133-43. doi: 10.1093/jhered/esp101. Epub 2009 Nov 27.
We examined spatial genetic structure (SGS) in Enterolobium cyclocarpum (the Guanacaste tree), a dominant tree of Central American dry forests in 4 sites in Guanacaste Province, Costa Rica. In disturbed dry forest sites (e.g., pastures), E. cyclocarpum is primarily dispersed by cattle and horses, whose movements are restricted by pasture boundaries. The study sites varied in tree densities and disturbance. Allozyme analyses of adult trees demonstrated significant levels of SGS in 3 of 4 sites. SGS was primarily due to clusters of young adults located along seasonal streams, rocky areas, and in abandoned pastures. SGS was highest in the first distance class in the least disturbed population, which also had the lowest density of large adults. Low, but significant SGS characterized the site with the highest number of large adults located in individual pastures. The semiurban site, had no clusters of young adults and, probably as a result, failed to exhibit SGS. Our results demonstrate that disturbance can strongly influence SGS patterns and are consistent with a landscape model in which the location of potential recruitment sites, restricted seed disperser movements, and the number and location of maternal individuals dictate the level and pattern of SGS.
我们研究了 Enterolobium cyclocarpum（中美洲干旱森林中的一种优势树种）的空间遗传结构（SGS），在哥斯达黎加瓜纳卡斯特省的 4 个地点对其进行了研究。在受干扰的干旱森林地点（例如牧场），E. cyclocarpum 主要由牛和马传播，它们的活动受到牧场边界的限制。研究地点的树木密度和干扰程度不同。成年树木的同工酶分析表明，在 4 个地点中的 3 个地点存在明显的 SGS。SGS 主要是由于沿季节性溪流、岩石区和废弃牧场分布的年轻成年人集群造成的。在受干扰最小的种群中，第一距离类别的 SGS 最高，该种群中大型成年个体的密度也最低。在个体牧场中存在大量大型成年个体的位点，其 SGS 虽然较低，但也具有显著意义。半城市地点没有年轻成年人集群，可能因此没有表现出 SGS。我们的结果表明，干扰可以强烈影响 SGS 模式，与景观模型一致，其中潜在的繁殖地位置、受限制的种子传播者的运动以及母本个体的数量和位置决定了 SGS 的水平和模式。
