Department of Conservation Biology, Estación Biológica de Doñana (CSIC), Avda. Américo Vespucio s/n, Isla de la Cartuja 41092 Sevilla, Spain.
Conserv Biol. 2012 Aug;26(4):689-97. doi: 10.1111/j.1523-1739.2012.01870.x. Epub 2012 Jun 25.
Theory suggests that demographic and genetic traits deteriorate (i.e., fitness and genetic diversity decrease) when populations become small, and that such deterioration could precipitate positive feedback loops called extinction vortices. We examined whether demographic attributes and genetic traits have changed over time in one of the 2 remaining small populations of the highly endangered Iberian lynx (Lynx pardinus) in Doñana, Spain. From 1983 to 2008, we recorded nontraumatic mortality rates, litter size, offspring survival, age at territory acquisition, and sex ratio. We combined these demographic attributes with measures of inbreeding and genetic diversity at neutral loci (microsatellites) and genes subjected to selection (major histocompatibility complex). Data on demographic traits were obtained through capture and radio tracking, checking dens during breeding, track surveys, and camera trapping. For genetic analyses, we obtained blood or tissue samples from captured or necropsied individuals or from museum specimens. Over time a female-biased sex ratio developed, age of territory acquisition decreased, mean litter size decreased, and rates of nontraumatic mortality increased, but there were no significant changes in overall mortality rates, standardized individual heterozygosity declined steadily, and allelic diversity of exon 2 of class II major histocompatibility complex DRB genes remained constant (2 allelic variants present in all individuals analyzed). Changes in sex ratio and age of territory acquisition may have resulted from demographic stochasticity, whereas changes in litter size and nontraumatic mortality may be related to observed increases in inbreeding. Concomitant deterioration of both demographic attributes and genetic traits is consistent with an extinction vortex. The co-occurrence, with or without interaction, of demographic and genetic deterioration may explain the lack of success of conservation efforts with the Doñana population of Iberian lynx.
理论表明，当种群规模变小时，人口的遗传特征和人口特征（即适应度和遗传多样性降低）会恶化，这种恶化可能会引发被称为灭绝旋涡的正反馈循环。我们研究了西班牙多尼亚纳（Doñana）仅剩的两个极度濒危的伊比利亚猞猁（Lynx pardinus）小种群之一的人口特征和遗传特征是否随时间发生了变化。从 1983 年到 2008 年，我们记录了非创伤性死亡率、产仔数、后代存活率、领地获得年龄和性别比例。我们将这些人口特征与中性基因座（微卫星）和受选择基因（主要组织相容性复合体）的近亲繁殖和遗传多样性测量值相结合。人口特征数据是通过捕捉和无线电跟踪、繁殖期检查巢穴、跟踪调查和相机陷阱获得的。对于遗传分析，我们从捕获或尸检的个体或博物馆标本中获取血液或组织样本。随着时间的推移，出现了雌性偏斜的性别比例，领地获得年龄降低，平均产仔数减少，非创伤性死亡率增加，但总体死亡率没有明显变化，标准化个体杂合度稳步下降，并且 II 类主要组织相容性复合体 DRB 基因外显子 2 的等位基因多样性保持不变（所有分析个体中均存在 2 个等位变体）。性别比例和领地获得年龄的变化可能是由人口随机性引起的，而产仔数和非创伤性死亡率的变化可能与观察到的近亲繁殖增加有关。人口特征和遗传特征的同时恶化与灭绝旋涡一致。人口和遗传恶化的共同发生（无论是否相互作用）可能解释了多尼亚纳伊比利亚猞猁种群保护工作的失败。
