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Parthenogenesis is defined as cell division in a female gamete without any genetic contribution from the male (Beatty 1967, Rougier & Werb 2001). When such cell division results in the development of an embryo parthenogenesis is known as ‘virgin birth’. Parthenogenesis occurs naturally in certain plants and animals and in the latter is most frequent among invertebrates (e.g. aphids and Daphnia ). Among vertebrates parthenogenetic development occurs in a small number of fish and reptile species (Soumalainen 1948, Watts et al . 2006) and has been recorded occasionally in mammals, including humans (Rougier & Werb 2001, Kono et al . 2004). Parthenogenetic development in birds was first reported in the domestic fowl Gallus domesticus (Oellacher 1872), but was also discovered in the domestic pigeon Columba livia (Bartelmez & Riddle 1924) and the domestic turkey Meleagris gallopavo (Olsen & Marsden 1954). In all three bird species parthenogenetic development was disorganised and almost always abortive. In the chicken, parthenogenetic development was relatively infrequent (< 5% of eggs) with only a single record of a parthenogenetic adult fowl (Sarvella 1973). Parthenogenesis was more common in the turkey (up to 20% of eggs; Olsen & Marsden 1954, Savage & Harper 1986) and by selective breeding an entire strain of parthenogenetic birds, all of which were male and some of which produced fertile spermatozoa, was produced (Olsen 1975). Parthenogenetic development has not been previously reported in any passerine birds (Johnson 2000). Here we report the occurrence of parthenogenetic development in the Zebra Finch Taeniopygia guttata . CRITERIA FOR DETERMINING PARTHENOGENETIC DEVELOPMENT |
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