Data from: Melanocortin 1 receptor (MC1R) gene sequence variation and melanism in the gray (Sciurus carolinensis), fox (Sciurus niger) and red (Sciurus vulgaris) squirrel

Sequence variations in the melanocortin 1 receptor (MC1R) gene are associated with melanism in many different species of mammals, birds, and reptiles. The gray squirrel (Sciurus carolinensis), found in the British Isles, was introduced from North America in the late 19th century. Melanism in the British gray squirrel is associated with a 24-bp deletion in the MC1R. To investigate the origin of this mutation, we sequenced the MC1R of 95 individuals including 44 melanic gray squirrels from both the British Isles and North America. Melanic gray squirrels of both populations had the same 24-bp deletion associated with melanism. Given the significant deletion associated with melanism in the gray squirrel, we sequenced the MC1R of both wild-type and melanic fox squirrels (Sciurus niger) (9 individuals) and red squirrels (Sciurus vulgaris) (39 individuals). Unlike the gray squirrel, no association between sequence variation in the MC1R and melanism was found in these 2 species. We conclude that the melanic gray squirrel found in the British Isles originated from one or more introductions of melanic gray squirrels from North America. We also conclude that variations in the MC1R are not associated with melanism in the fox and red squirrels.

黑素皮质素1受体（melanocortin 1 receptor, MC1R）基因的序列变异，与哺乳类、鸟类及爬行类诸多物种的黑化现象密切相关。分布于不列颠群岛的灰松鼠（Sciurus carolinensis）于19世纪末从北美引入。不列颠群岛灰松鼠的黑化现象，与其MC1R基因上一段24bp的缺失突变存在关联。为探究该突变的起源，本研究对来自不列颠群岛与北美共95只个体的MC1R基因进行了测序，其中包含44只黑化灰松鼠。两个地理种群的黑化灰松鼠均携带了与黑化现象相关的同一处24bp缺失突变。鉴于灰松鼠中该缺失突变与黑化现象的显著关联，本研究进一步对野生型与黑化狐松鼠（Sciurus niger，共9只个体）以及欧亚红松鼠（Sciurus vulgaris，共39只个体）的MC1R基因进行了测序。与灰松鼠不同，这两个物种的MC1R序列变异与黑化现象均未发现显著关联。本研究据此推断，不列颠群岛的黑化灰松鼠起源于北美黑化灰松鼠的一次或多次引入事件。本研究同时证实，狐松鼠与欧亚红松鼠的MC1R基因变异与黑化现象并无关联。