What Are Factors Affecting Variation In Chicken Characteristics?
Here’s one: A new mutation of the chicken that causes a reduction in eyeball size is described. Eyeball size reduction is extreme in over 80% of affected individuals. Two-thirds of affected chickens have bilateral expression, while the rest are unilaterally affected. The trait appears to affect liveability beyond that which might be expected of blind individuals. Embryonic mortality was increased five-fold among microphthalmic individuals, and all but two of the 35 microphthalmic chicks that hatched died within a week. Data from various crosses indicate that this condition is inherited as an autosomal recessive with expression being limited primarily to females. The name microphthalmia-4 and the gene symbol mi-4 are proposed for this trait.
