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Breakdown of Isolation Mechanisms in Two Species of Captive Junglefowl (Gallus gallus and Gallus sonneratii)
G. Victor Morejohn
Vol. 22, No. 3 (Sep., 1968), pp. 576-582
Published by: Society for the Study of Evolution
Stable URL: http://www.jstor.org/stable/2406881
Page Count: 7
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No difficulty was experienced raising numerous young of G. gallus. Much difficulty was experienced raising young of G. sonneratii. Interspecific hybridization was accomplished only by use of the sonneratii cock and gallus hens. The audiovisual, behavioral isolation mechanisms (voice and color of cock) which prevented hybridizing at first, were overcome, in part, by raising the hens to be used for hybridizing in pens adjacent to the sonneratii cocks. Interspecific hybrids of both sexes were readily obtained and raised to maturity. The vigorous hybrids were crossed among themselves and with both parental species. No members of the F2 generation survived. Most of the mortality occurred during incubation. Many abnormal anatomical conditions were found in the dead embryos. Limited backcross generations were produced, some of which hatched and grew to maturity. I conclude from these data that, aside from geographic isolation, courtship behavior as well as genic incompatibility are chiefly responsible for maintaining both species as separate taxonomic units in the wild.
Evolution © 1968 Society for the Study of Evolution