Bijlsma R, Bundgaard J, Boerema A C, Van Putten W F
Department of Genetics, University of Groningen, Haren, The Netherlands.
EXS. 1997;83:193-207. doi: 10.1007/978-3-0348-8882-0_11.
Many populations of endangered species have to cope both with stressful and deteriorating environmental conditions (mostly the primary cause of the endangerment) and with an increase in homozygosity due to genetic drift and/or inbreeding in small isolated populations. The latter will result in genetic stress often accompanied by a decrease in fitness (inbreeding depression). We have studied the consequences of genetic stress, under optimal as well as stressful environmental conditions, for the fitness and persistence of small populations using Drosophila melanogaster as a model system. The results show that, already under optimal environmental conditions, an increase in homozygosity or inbreeding both impairs fitness and increases the extinction risk of populations significantly. Under environmental stress, however, these effects become greatly enhanced. More important, the results show that the impact of environmental stress becomes significantly greater for higher inbreeding levels. This explicitly demonstrates that genetic and environmental stress are not independent but can act synergistically. This apparent interaction may have important consequences for the conservation of endangered species.
许多濒危物种群体既要应对压力大且不断恶化的环境条件（这大多是物种濒危的主要原因），又要应对因小的孤立种群中的遗传漂变和/或近亲繁殖导致的纯合度增加。后者会导致遗传压力，常常伴随着适合度下降（近亲繁殖衰退）。我们以黑腹果蝇作为模型系统，研究了在最佳环境条件以及压力环境条件下，遗传压力对小种群适合度和存续的影响。结果表明，即使在最佳环境条件下，纯合度增加或近亲繁殖都会损害适合度，并显著增加种群灭绝风险。然而，在环境压力下，这些影响会大大增强。更重要的是，结果表明，对于更高的近亲繁殖水平，环境压力的影响会显著更大。这明确表明，遗传压力和环境压力并非相互独立，而是可以协同作用。这种明显的相互作用可能对濒危物种的保护具有重要意义。
