Hybridizing Old and New World camelids: Camelus dromedarius x Lama guanicoe

Abstract

Thirty female dromedary camels were inseminated on a total of 50 occasions with 2^4 ml of fresh guanaco semen diluted with an equal volume of commercially available camel semen extender. Similarly, nine female guanacos were inseminated on 34 occasions with 4^6 ml of fresh, diluted camel semen. Only two of the dromedary females conceived; one aborted a female foetus on day 260 of gestation and the other gave birth to a stillborn female calf on day 365. Six conceptions occurred in the female guanacos. Two of these conceptuses, diagnosed by ultrasound, were resorbed between days 25 and 40 of gestation, one female foetus was aborted on day 291, another female foetus was aborted on day 302, and one female calf was stillborn on day 365 of gestation. The sixth foetus, a male, was born prematurely but alive after a 328-day gestation. It had a phenotypic appearance intermediate between that of a camel and a guanaco and its hybrid parentage was con¢rmed by the DNA ¢ngerprinting of eight llama microsatellites. To our knowledge, this is the ¢rst viable hybrid ever to be produced between Old World and New World camelids, which have been reproductively isolated from one another for at least 11 million years. The preponderance of female hybrids is in accordance with Haldane's law. Histological examination of their ovaries revealed a failure of meiosis, with only an occasional abnormal oocyte surrounded by follicle cells. Although the diploid chromosone number of camels and guanacos is the same (2n 74), su¤cient genetic change has taken place to make the pairing of homologous chromosomes no longer possible.

Cytogenetic characterization of alpaca (<i>Lama pacos</i>, fam. Camelidae) prometaphase chromosomes

“…They found the GTG-banding patterns of the bactrian, llama and guanaco quite identical to each other, thus suggesting that the amount of divergent evolution which has occurred in the family Camelidae has been accomplished, mainly, by single gene mutations or minor chromosomal rearrangements. However, a recent report on failure of hybridization between a female dromedary and a gua- naco stallion (Skidmore et al, 1999) would indicate that, despite the extensive similarity in the diploid number and chromosome banding, sufficient genetic change has taken place to make the pairing of homologous chromosomes no longer possible. This finding points out the need to explore chromosome homologies within the family Camelidae by using more effective techniques, such as high resolution banding, cross-species fluorescent in situ hybridization (ZOO-FISH) with chromosome specific painting probes and/or chromosome markers, and gene mapping.…”

Cross-species chromosome painting among camel, cattle, pig and human: further insights into the putative Cetartiodactyla ancestral karyotype

“…Gray (1972) reported that interbreeding can take place between the two Old World camelids with fertile offspring, and the same is true for the New World camelids. More recently, it was shown that representatives of the Old World camelids and New World camelids can cross-hybridize via artificial insemination (Skidmore et al 1999).…”

Dobzhansky–Muller incompatibilities in protein evolution

“…In Drosophila (11,38) and mammals (39,40) many pairs of species that accumulated differences at Ϸ10 5 or more amino acid sites can produce viable or even fertile hybrids. This implies that between closely related species F Ͻ 10 Ϫ5 , in an apparent discrepancy with our estimate of F Ϸ 10 Ϫ1 .…”