安康羊

安康羊
保護狀態	滅絕
別名	"Otter sheep"
原產地	美國
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）是一種家羊，有着長軀體和極短的短腿，且前腿是彎曲的。該術語通常用於指代由生於1791年馬薩諸塞州的一隻羊所繁育的後代。該品種由人工選擇而成，並維持其無法跳越圍欄的性狀，但當不再需要時，於1876年滅絕。^[1]

「安康」的名稱也用於指其他具有相同表現型品系的綿羊，例如從生於1919年的個體繁育的挪威原種，和從生於1962年的個體繁育的德州原種。在科學家不再需要他們的基因用作研究後，也讓這些譜系滅絕。^[1]^[2]

英國萊斯特的考古發掘還發現，約公元1500年出現了有安康羊特徵的掌骨、跖骨、趾骨，從而表明該表現型至少已獨立出現過四次。^[1]

安康羊的獨特特性是由一個隱性侏儒突變引起的，其往往能導致癱瘓。該突變的具體作用是能導致軟骨營養不良。^[1]^[3]

生物學歷史上的意義

儘管安康羊為數不多、其貌不揚，它在生物學歷史上的貢獻卻是巨大的。查爾斯·達爾文的《物種起源》中有幾章指明安康羊作為他的論點，即後代從父母繼承獨特特徵的一個例子。通過它所駁斥的觀點，即博物學家和育種者長期持有的信念：遺傳性狀是由父母的性狀「混合」而成的，也許能更好地理解這個概念。^[4]如果這是真的，那麼安康羊與一隻普通羊後代的身高就應介於父母兩者之間。相反，產生的後代要麼是安康的，或是普通的，從而支持了達爾文的觀點。

參考

^ ^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. （原始內容存檔於2014-04-13）. 請檢查|date=中的日期值 (幫助)
^ 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. （原始內容存檔於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. （原始內容存檔於2014-04-13）. 請檢查|date=中的日期值 (幫助)

[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. （原始內容存檔於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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