Winkler Manuela, Koch Marcus, Hietz Peter
Department of Integrative Biology, Institute of Botany, University of Natural Resources and Life Sciences (Boku), Gregor-Mendel-Str. 33, 1180 Vienna, Austria.
Conserv Genet. 2011;12(6):1411-1420. doi: 10.1007/s10592-011-0239-4. Epub 2011 Jul 2.
Tropical montane forests suffer from increasing fragmentation and replacement by other types of land-use such as coffee plantations. These processes are known to affect gene flow and genetic structure of plant populations. Epiphytes are particularly vulnerable because they depend on their supporting trees for their entire life-cycle. We compared population genetic structure and genetic diversity derived from AFLP markers of two epiphytic fern species differing in their ability to colonize secondary habitats. One species, , is a successful colonizer of shade trees and isolated trees whereas the other species, , is restricted to forests with anthropogenic separation leading to significant isolation between populations. By far most genetic variation was distributed within rather than among populations in both species, and a genetic admixture analysis did not reveal any clustering. Gene flow exceeded by far the benchmark of one migrant per generation to prevent genetic divergence between populations in both species. Though populations are threatened by habitat loss, long-distance dispersal is likely to support gene flow even between distant populations, which efficiently delays genetic isolation. Consequently, populations may rather be threatened by ecological consequences of habitat loss and fragmentation.
热带山地森林正日益遭受破碎化，并且被咖啡种植园等其他土地利用类型所取代。已知这些过程会影响植物种群的基因流动和遗传结构。附生植物尤其脆弱，因为它们在整个生命周期都依赖于支撑它们的树木。我们比较了两种附生蕨类植物的种群遗传结构和基于AFLP标记的遗传多样性，这两种蕨类植物在定殖次生栖息地的能力上有所不同。一种物种， ，是遮荫树和孤立树木的成功定殖者，而另一种物种， ，则仅限于有人为隔离导致种群间显著隔离的森林。到目前为止，两种物种中绝大多数遗传变异分布在种群内部而非种群之间，遗传混合分析未发现任何聚类现象。两种物种的基因流动远远超过了每代一个迁移个体的基准，以防止种群间的遗传分化。尽管种群受到栖息地丧失的威胁，但远距离扩散可能支持即使是遥远种群之间的基因流动，从而有效地延迟遗传隔离。因此，种群可能更多地受到栖息地丧失和破碎化的生态后果的威胁。
