Département de biologie, Université de Sherbrooke, Sherbrooke, QC, Canada.
J Evol Biol. 2011 Jan;24(1):121-31. doi: 10.1111/j.1420-9101.2010.02154.x. Epub 2010 Nov 2.
Although it is generally expected that inbreeding would lower fitness, few studies have directly quantified the effects of inbreeding in wild mammals. We investigated the effects of inbreeding using long-term data from bighorn sheep on Ram Mountain, Alberta, Canada, over 20 years. This population underwent a drastic decline from 1992 to 2002 and has since failed to recover. We used a pedigree to calculate inbreeding coefficients and examined their impact on lamb growth, birth date and survival. Inbreeding had a substantial effect on female survival: for a given mass in September, the probability of overwinter survival for inbred female lambs was about 40% lower than that of noninbred ones. Contrary to our expectations, inbred female lambs were born earlier than noninbred ones. Earlier birth led to inbred female lambs being heavier by mid-September than noninbred ones. There was a nonsignificant trend for inbred female yearlings to weigh more than noninbred ones. A stronger mass-dependent viability selection for inbred compared to noninbred female lambs may explain why surviving inbred females were heavier than noninbred ones. Survival of male lambs was not affected by inbreeding. Sex-differential effects of inbreeding may be a general pattern in sexually dimorphic mammals, because of sex-biased maternal care or sexual differences in early development strategies.
尽管人们普遍认为近亲繁殖会降低适应度，但很少有研究直接量化了野生哺乳动物近亲繁殖的影响。我们利用加拿大阿尔伯塔省拉姆斯山 20 多年的绵羊长期数据，研究了近亲繁殖的影响。该种群在 1992 年至 2002 年间急剧减少，此后一直未能恢复。我们使用系谱来计算近交系数，并研究了它们对羔羊生长、出生日期和存活率的影响。近亲繁殖对母羊的存活率有显著影响：对于 9 月的给定体重，近亲繁殖母羊的越冬存活率比非近亲繁殖母羊低约 40%。与我们的预期相反，近亲繁殖的母羊比非近亲繁殖的母羊出生更早。更早的出生导致近亲繁殖的母羊在 9 月中旬比非近亲繁殖的母羊更重。近亲繁殖的母羊比非近亲繁殖的母羊更重，但没有显著趋势。与非近亲繁殖的母羊相比，近亲繁殖的母羊在体重上可能受到更强的依赖体重的生存选择，这可能解释了为什么幸存的近亲繁殖母羊比非近亲繁殖母羊更重。公羊羔的存活率不受近亲繁殖的影响。近亲繁殖的性别差异效应可能是性二态哺乳动物的一种普遍模式，因为母性照顾存在性别偏见，或者早期发育策略存在性别差异。
