Stanley Craig E, Kulathinal Rob J
Department of Biology, Temple University, Philadelphia, PA, USA.
BMC Evol Biol. 2016 Jan 5;16:6. doi: 10.1186/s12862-015-0580-1.
Domesticated animals quickly evolve docile and submissive behaviors after isolation from their wild conspecifics. Model organisms reared for prolonged periods in the laboratory also exhibit similar shifts towards these domesticated behaviors. Yet whether this divergence is due to inadvertent selection in the lab or the fixation of deleterious mutations remains unknown.
Here, we compare the genomes of lab-reared and wild-caught Drosophila melanogaster to understand the genetic basis of these recently endowed behaviors common to laboratory models. From reassembled genomes of common lab strains, we identify unique, derived variants not present in global populations (lab-specific SNPs). Decreased selective constraints across low frequency SNPs (unique to one or two lab strains) are different from patterns found in the wild and more similar to neutral expectations, suggesting an overall accumulation of deleterious mutations. However, high-frequency lab SNPs found in most or all lab strains reveal an enrichment of X-linked loci and neuro-sensory genes across large extended haplotypes. Among shared polymorphisms, we also find highly differentiated SNPs, in which the derived allele is higher in frequency in the wild (Fst*wild>lab), enriched for similar neurogenetic ontologies, indicative of relaxed selection on more active wild alleles in the lab.
Among random mutations that continuously accumulate in the laboratory, we detect common adaptive signatures in domesticated lab strains of fruit flies. Our results demonstrate that lab animals can quickly evolve domesticated behaviors via unconscious selection by humans early on a broad pool of disproportionately large neurogenetic targets followed by the fixation of accumulated deleterious mutations on functionally similar targets.
家养动物在与野生同类隔离后会迅速进化出温顺和顺从的行为。在实验室中长期饲养的模式生物也表现出向这些驯化行为的类似转变。然而，这种差异是由于实验室中的无意选择还是有害突变的固定尚不清楚。
在这里，我们比较了实验室饲养和野生捕获的黑腹果蝇的基因组，以了解这些实验室模型共有的新出现行为的遗传基础。从常见实验室菌株的重新组装基因组中，我们鉴定出全球种群中不存在的独特衍生变体（实验室特异性单核苷酸多态性）。低频单核苷酸多态性（一两个实验室菌株特有的）上选择性限制的降低与在野生环境中发现的模式不同，更类似于中性预期，表明有害突变的总体积累。然而，在大多数或所有实验室菌株中发现的高频实验室单核苷酸多态性揭示了跨大型扩展单倍型的X连锁基因座和神经感觉基因的富集。在共享多态性中，我们还发现了高度分化的单核苷酸多态性，其中衍生等位基因在野生环境中的频率更高（Fst*野生>实验室），富集了相似的神经遗传学本体，表明实验室中对更活跃的野生等位基因的选择放松。
在实验室中不断积累的随机突变中，我们在驯化的果蝇实验室菌株中检测到常见的适应性特征。我们的结果表明，实验动物可以通过人类早期在大量不成比例的大神经遗传靶点上的无意识选择，然后在功能相似的靶点上固定积累的有害突变，迅速进化出驯化行为。
