Lienert Judit, Fischer Markus, Schneller Jakob, Diemer Matthias
Institut für Umweltwissenschaften, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland;
Am J Bot. 2002 May;89(5):801-11. doi: 10.3732/ajb.89.5.801.
We examined the effects of size and spatial isolation of fens on the isozyme variability of 17 populations of Swertia perennis. This long-lived perennial is a locally abundant fen specialist in Switzerland, where wetlands have been strongly fragmented. Isozyme variability was comparable to other outcrossing plants (A = 1.53, AP(p) = 2.01, P(p) = 42.5, H(o) = 0.113, H(e) = 0.139). F statistics indicated both inbreeding within and differentiation between populations (F(IS) = 0.076, F(IT) = 0.194, F(ST) = 0.128), with moderate gene flow between populations (N(e)m = 1.703). Populations in small, isolated fens had reduced genetic variability and the highest within-population inbreeding coefficients (F(IS)). Isozyme variability was significantly associated with vegetative fitness traits (MANOVA), and the magnitude of leaf herbivory decreased as the percentage of polymorphic loci increased. These data suggest that the reduced genetic variability of S. perennis in small, isolated populations may reduce plant fitness, thereby increasing susceptibility to herbivore damage. Our study also shows that habitat fragmentation can reduce the genetic variability of populations of fairly common habitat specialists, which so far have attracted less conservation attention than rare species.
我们研究了沼泽湿地的面积大小和空间隔离对17个多年生獐牙菜种群同工酶变异性的影响。这种多年生植物寿命较长，在瑞士是当地常见的沼泽湿地特有物种，而当地的湿地已严重破碎化。其同工酶变异性与其他异交植物相当（A = 1.53，AP(p) = 2.01，P(p) = 42.5，H(o) = 0.113，H(e) = 0.139）。F统计量表明种群内存在近亲繁殖且种群间存在分化（F(IS) = 0.076，F(IT) = 0.194，F(ST) = 0.128），种群间基因流适中（N(e)m = 1.703）。处于小型孤立沼泽湿地中的种群遗传变异性降低，且种群内近亲繁殖系数（F(IS)）最高。同工酶变异性与营养体适合度性状显著相关（多变量方差分析），并且随着多态位点百分比的增加，叶片被食草动物啃食的程度降低。这些数据表明，小型孤立种群中多年生獐牙菜遗传变异性的降低可能会降低植物适合度，从而增加对食草动物损害的易感性。我们的研究还表明，栖息地破碎化会降低相当常见的栖息地特有物种种群的遗传变异性，而迄今为止，这些物种受到的保护关注比稀有物种少。
