安康羊

安康羊
保護狀態	灭绝
別名	"Otter sheep"
原產地	美国
特徵
體重	雄：45磅
毛色	白色
臉色	白色
Notes
	侏儒
	綿羊; Ovis aries

安康羊（英語：Ancon sheep，又名英語："Otter" sheep）是一种家羊，有着长躯体和极短的短腿，且前腿是弯曲的。该术语通常用于指代由生于1791年马萨诸塞州的一只羊所繁育的后代。该品种由人工选择而成，并维持其无法跳越围栏的性状，但当不再需要时，于1876年灭绝。^[1]

“安康”的名称也用于指其他具有相同表现型品系的绵羊，例如从生于1919年的个体繁育的挪威原种，和从生于1962年的个体繁育的德州原种。在科学家不再需要他们的基因用作研究后，也让这些谱系灭绝。^[1]^[2]

英国莱斯特的考古发掘还发现，约公元1500年出现了有安康羊特征的掌骨、跖骨、趾骨，从而表明该表现型至少已独立出现过四次。^[1]

安康羊的独特特性是由一个隐性侏儒突变引起的，其往往能导致瘫痪。该突变的具体作用是能导致软骨营养不良。^[1]^[3]

生物学历史上的意义

尽管安康羊为数不多、其貌不扬，它在生物学历史上的贡献却是巨大的。查尔斯·达尔文的《物种起源》中有几章指明安康羊作为他的论点，即后代从父母继承独特特征的一个例子。通过它所驳斥的观点，即博物学家和育种者长期持有的信念：遗传性状是由父母的性状“混合”而成的，也许能更好地理解这个概念。^[4]如果这是真的，那么安康羊与一只普通羊后代的身高就应介于父母两者之间。相反，产生的后代要么是安康的，或是普通的，从而支持了达尔文的观点。

参考

^ ^1.0 ^1.1 ^1.2 ^1.3 Gidney, Louisa. Earliest Archaeological Evidence of the Ancon Mutation in Sheep from Leicester, UK. International Journal of Osteoarchaeology (John Wiley and Sons). May/June 2007, 17 (3): 318–321. ISSN 1099-1212. doi:10.1002/oa.872.
^ Shelton, Maurice. A recurrence of the Ancon dwarf in Merino sheep (PDF). Journal of Heredity (John Wiley and Sons). 1968, 59 (5): 267–268 [2014-03-07]. PMID 5753237.
^ T. K. Chang. Crippling in chondrodystrophic (Ancon) sheep. Growth. 1949-9, 13 (3): 299–307 [2019-02-13]. ISSN 0017-4793. PMID 18142372. （原始内容存档于2014-04-13）. 请检查|date=中的日期值 (帮助)
^ Schwartz, Karlene; Vogel, Jane. Unraveling the Yarn of the Ancon Sheep. BioScience (Oxford University Press). Dec 1994, 44 (11): 764–768 [2014-07-03]. ISSN 0006-3568. doi:10.2307/1312585. （原始内容存档于2003-08-11）. Ancon sheep are important to the history of biology because Charles Darwin used them to support his argument that animals inherit parental traits without blending: "When turnspit dogs and Ancon sheep, both of which have dwarfed limbs, are crossed with common breeds, the offspring are not intermediate in structure, but take after either parent." Before Darwin's day, many plant and animal breeders assumed that parental traits would mingle in the offspring.

[gidney-1] 1.0 ^1.1 ^1.2 ^1.3 Gidney, Louisa. Earliest Archaeological Evidence of the Ancon Mutation in Sheep from Leicester, UK. International Journal of Osteoarchaeology (John Wiley and Sons). May/June 2007, 17 (3): 318–321. ISSN 1099-1212. doi:10.1002/oa.872.

[shelton-2] Shelton, Maurice. A recurrence of the Ancon dwarf in Merino sheep (PDF). Journal of Heredity (John Wiley and Sons). 1968, 59 (5): 267–268 [2014-03-07]. PMID 5753237.

[chang1949-3] T. K. Chang. Crippling in chondrodystrophic (Ancon) sheep. Growth. 1949-9, 13 (3): 299–307 [2019-02-13]. ISSN 0017-4793. PMID 18142372. （原始内容存档于2014-04-13）. 请检查|date=中的日期值 (帮助)

[bioscience1994-4] Schwartz, Karlene; Vogel, Jane. Unraveling the Yarn of the Ancon Sheep. BioScience (Oxford University Press). Dec 1994, 44 (11): 764–768 [2014-07-03]. ISSN 0006-3568. doi:10.2307/1312585. （原始内容存档于2003-08-11）. Ancon sheep are important to the history of biology because Charles Darwin used them to support his argument that animals inherit parental traits without blending: "When turnspit dogs and Ancon sheep, both of which have dwarfed limbs, are crossed with common breeds, the offspring are not intermediate in structure, but take after either parent." Before Darwin's day, many plant and animal breeders assumed that parental traits would mingle in the offspring.

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