van Oosterhout Cock, Smith Alan M, Hänfling Bernd, Ramnarine Indar W, Mohammed Ryan S, Cable Joanne
Molecular Ecology and Fisheries Genetics Laboratory, University of Hull, Hull, HU6 7RX, United Kingdom.
Conserv Biol. 2007 Dec;21(6):1573-83. doi: 10.1111/j.1523-1739.2007.00809.x.
Ex situ conservation is of increasing importance to prevent the extinction of endangered animals in the wild. Despite low success rates of reintroduction programs few researchers have investigated empirically the efficacy of captive breeding regimes for the release of captive-bred vertebrates. We used guppies (Poecilia reticulata) from two populations in Trinidad to compare different conservation breeding regimes. The upper Aripo population was chosen for its small effective population size (N(e) approximately 100) and genetic isolation, which makes it representative of many endangered natural populations. By contrast, the lower Aripo population is a genetically diverse, much larger population (N(e) approximately 2400). We examined three captive-breeding regimes: (1) inbreeding fish crossed with their full siblings, (2) minimized inbreeding, no consanguineous matings, and (3) control fish crossed at random. We kept pedigree records for all regimes so that we could calculate inbreeding coefficients over four generations. The body size and fertility of guppies was significantly reduced due to inbreeding depression. The genetic load of sterile equivalents was particularly high for the lower Aripo population. Body size also declined due to breeding conditions in the captive environment. After four generations in captivity, the fish were released into a mesocosm in Trinidad. Captive-bred guppies were extremely susceptible to gyrodactylid parasites (58% survival rate) compared with their wild counterparts (96% survival). A reduced level of immunogenetic variation due to inbreeding and lack of exposure to natural parasites may have rendered captive-bred individuals more prone to infectious disease. The threat of disease outbreak is particularly high when naive captive-bred hosts are released in wild populations. Susceptible, captive-bred hosts could facilitate the transmission of parasites throughout the wild population, thus initiating an epidemic. This risk could potentially be reduced by prior exposure to parasites before release and gradual release of captive-bred individuals.
迁地保护对于防止野生濒危动物灭绝日益重要。尽管再引入计划的成功率较低，但很少有研究人员实证调查圈养繁殖方式对于放归圈养繁殖脊椎动物的效果。我们利用特立尼达两个种群的孔雀鱼（孔雀花鳉）来比较不同的保护繁殖方式。选择上阿里波种群是因为其有效种群规模小（有效种群数量约为100）且基因隔离，这使其成为许多濒危自然种群的代表。相比之下，下阿里波种群是一个基因多样、规模大得多的种群（有效种群数量约为2400）。我们研究了三种圈养繁殖方式：（1）近亲繁殖的鱼与它们的全同胞杂交，（2）近亲繁殖最小化，无近亲交配，（3）对照鱼随机杂交。我们记录了所有方式的系谱，以便能够计算四代的近亲繁殖系数。由于近亲繁殖衰退，孔雀鱼的体型和繁殖力显著降低。对于下阿里波种群，不育等效物的遗传负荷特别高。由于圈养环境中的繁殖条件，体型也有所下降。在圈养四代后，这些鱼被放归到特立尼达的一个中型生态系统中。与野生孔雀鱼（存活率96%）相比，圈养繁殖的孔雀鱼极易感染三代虫寄生虫（存活率58%）。由于近亲繁殖和缺乏接触自然寄生虫导致免疫遗传变异水平降低，可能使圈养繁殖个体更容易感染传染病。当未经接触的圈养繁殖宿主放归野生种群时，疾病爆发的威胁尤其高。易感的圈养繁殖宿主可能会促进寄生虫在整个野生种群中的传播，从而引发疫情。通过放归前预先接触寄生虫和逐步放归圈养繁殖个体，这种风险可能会潜在降低。
