Andrade I M, Mayo S J, van den Berg C, Fay M F, Chester M, Lexer C, Kirkup D
Programa de Pós-Graduação em Botânica, Universidade Estadual de Feira de Santana (UEFS), Departamento de Ciências Biológicas, Avenida Universitária s/n, 44031-460, Feira de Santana, Bahia, Brazil.
Ann Bot. 2007 Dec;100(6):1143-54. doi: 10.1093/aob/mcm200. Epub 2007 Sep 5.
This study sought genetic evidence of long-term isolation in populations of Monstera adansonii var. klotzschiana (Araceae), a herbaceous, probably outbreeding, humid forest hemi-epiphyte, in the brejo forests of Ceará (north-east Brazil), and clarification of their relationships with populations in Amazonia and the Atlantic forest of Brazil.
Within-population genetic diversity and between-population dissimilarity were estimated using AFLP molecular markers in 75 individuals from eight populations located in Ceará, the Brazilian Atlantic Forest and Amazonia.
The populations showed a clinal pattern of weak genetic differentiation over a large geographical region (F(ST) = 0.1896). A strong correlation between genetic and geographical distance (Mantel test: r = 0.6903, P = 0.002) suggests a historical pattern of isolation by distance. Genetic structure analysis revealed at least two distinct gene pools in the data. The two isolated Ceará populations are significantly different from each other (pairwise Phi(PT) = 0.137, P = 0.003) and as diverse (Nei's gene diversity, average H(e) = 0.1832, 0.1706) as those in the Atlantic and Amazon forest regions. The population in southern Brazil is less diverse (Nei's gene diversity, average H(e) = 0.127) than the rest. The Ceará populations are related to those of the Atlantic forest rather than those from Amazonia (AMOVA, among-groups variation = 11.95 %, P = 0.037).
The gene pools detected within an overall pattern of clinal variation suggest distinct episodes of gene flow, possibly correlated with past humid forest expansions. The Ceará populations show no evidence of erosion of genetic diversity, although this was expected because of their isolation. Their genetic differentiation and relatively high diversity reinforce the importance of conserving the endangered brejo forests.
本研究旨在寻找锦叶龟背竹（天南星科）种群长期隔离的遗传证据，锦叶龟背竹是一种草本、可能异花授粉的潮湿森林半附生植物，生长在巴西东北部塞阿拉州的陡坡森林中，并阐明其与亚马逊地区和巴西大西洋森林种群的关系。
利用AFLP分子标记对来自塞阿拉州、巴西大西洋森林和亚马逊地区的8个种群的75个个体进行种群内遗传多样性和种群间差异评估。
种群在大地理区域内呈现出渐变的弱遗传分化模式（F(ST)=0.1896）。遗传距离与地理距离之间的强相关性（Mantel检验：r = 0.6903，P = 0.002）表明存在距离隔离的历史模式。遗传结构分析揭示数据中至少有两个不同的基因库。两个隔离的塞阿拉种群彼此显著不同（成对Phi(PT)=0.137，P = 0.003），并且与大西洋和亚马逊森林地区的种群一样多样（Nei氏基因多样性，平均H(e)=0.1832，0.1706）。巴西南部的种群多样性较低（Nei氏基因多样性，平均H(e)=0.127）。塞阿拉种群与大西洋森林的种群相关，而非与亚马逊地区的种群相关（AMOVA，组间变异=11.95%，P = 0.037）。
在渐变变异的总体模式中检测到的基因库表明存在不同的基因流事件，可能与过去潮湿森林的扩张有关。塞阿拉种群没有遗传多样性受到侵蚀的证据，尽管由于其隔离状态预计会出现这种情况。它们的遗传分化和相对较高的多样性强化了保护濒危陡坡森林的重要性。
