Low genetic diversity in Antarctic populations of the lichen-forming ascomycete Cetraria aculeata and its photobiont
Low genetic diversity in Antarctic populations of the lichen-forming ascomycete Cetraria aculeata and its photobiont
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DOI：
10.3402/polar.v31i0.17353
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发表时间：
2012-01-01
期刊：
影响因子：
1.9
通讯作者：
Printzen, Christian
中科院分区：
文献类型：
--
作者：
Domaschke, Stephanie;Fernandez-Mendoza, Fernando;Printzen, Christian
地衣，真菌（真菌）和绿色藻类或蓝细菌（光生菌）的共生体，是特别适合承受不利环境条件的多水生物。因此，南极的陆地生态系统主要由地衣主导。全球气候变化的影响在海洋南极特别明显，可以假设地衣植被将在未来发生深刻的变化。种群的遗传多样性与其适应不断变化的环境条件的能力及其未来的进化潜力密切相关。在这项研究中，我们提出的证据表明，低遗传多样性在南极mycobiont和photobiont人口广泛的地衣Cetraria aculeata。我们比较了110和219之间的DNA序列从每个共生体的三个基因位点。共222个人从3个南极和9个antiboreal，温带和北极种群进行了调查。北极地区的真菌生物多样性最高，而温带地区的光合生物多样性最高。南极的光合生物多样性显著下降，但对北极不太明显，表明生态因素在决定南极光合生物种群的多样性中起着次要作用。为四个地理区域计算的丰富度估计数表明，南极种群的低遗传多样性并不是一个抽样假象。Cetraria aculeata似乎已经在北极多样化，随后将其范围扩大到南半球。南极遗传多样性的减少很可能是由于长距离殖民过程中的奠基者效应。
Lichens, symbiotic associations of fungi (mycobionts) and green algae or cyanobacteria (photobionts), are poikilohydric organisms that are particularly well adapted to withstand adverse environmental conditions. Terrestrial ecosystems of the Antarctic are therefore largely dominated by lichens. The effects of global climate change are especially pronounced in the maritime Antarctic and it may be assumed that the lichen vegetation will profoundly change in the future. The genetic diversity of populations is closely correlated to their ability to adapt to changing environmental conditions and to their future evolutionary potential. In this study, we present evidence for low genetic diversity in Antarctic mycobiont and photobiont populations of the widespread lichen Cetraria aculeata. We compared between 110 and 219 DNA sequences from each of three gene loci for each symbiont. A total of 222 individuals from three Antarctic and nine antiboreal, temperate and Arctic populations were investigated. The mycobiont diversity is highest in Arctic populations, while the photobionts are most diverse in temperate regions. Photobiont diversity decreases significantly towards the Antarctic but less markedly towards the Arctic, indicating that ecological factors play a minor role in determining the diversity of Antarctic photobiont populations. Richness estimators calculated for the four geographical regions suggest that the low genetic diversity of Antarctic populations is not a sampling artefact. Cetraria aculeata appears to have diversified in the Arctic and subsequently expanded its range into the Southern Hemisphere. The reduced genetic diversity in the Antarctic is most likely due to founder effects during long-distance colonization.