More strikingly, the finding shows that the babies produced from this asexual reproduction have attributes previously believed to be impossible. New evidence shows that boa constrictors can reproduce without sex. But one boa constrictor had babies asexually and the old-fashioned way.
Her sexually produced snake left is shown beside one of the asexually produced females right. This is the first time asexual reproduction, known in the scientific world as parthenogenesis, has been attributed to boa constrictors, says Dr. Warren Booth, an NC State postdoctoral researcher in entomology and the lead author of a paper describing the study. He adds that the results may force scientists to re-examine reptile reproduction, especially among more primitive snake species like boa constrictors.
The study is published online in Biology Letters, a Royal Society journal. Yet in the study, all the female babies produced by asexual reproduction had WW chromosomes, a phenomenon Booth says had not been seen before and was believed to be impossible.
Only through complex manipulation in lab settings could such WW females be produced — and even then only in fish and amphibians, Booth says. One brood contained 12 babies and the second contained 10 babies. Male snakes were present and courted the female before she gave birth to the rare babies.
Booth doubts that the rare births were caused by environmental changes. Then, when a suitable mate is available, revert back to sexual reproduction. When the all-female snake babies reach sexual maturity in a few years, Booth will be interested to see if they mate with a male, produce babies without a mate, or — like their mother — do both.
Coby Schal and Ed Vargo co-authored the paper. Co-author Sharon Moore raised the snakes in the study. Co-author and veterinarian Daniel Johnson provided surgical sex testing on the snakes. Parthenogenesis in vertebrates is considered an evolutionary novelty.
In snakes, all of which exhibit genetic sex determination with ZZ: ZW sex chromosomes, this rare form of asexual reproduction has failed to yield viable female WW offspring. Only through complex experimental manipulations have WW females been produced, and only in fish and amphibians. Through microsatellite DNA fingerprinting, we provide the first evidence of facultative parthenogenesis in a Boa constrictor, identifying multiple, viable, non-experimentally induced females for the first time in any vertebrate lineage.
Although the elevated homozygosity of the offspring in relation to the mother suggests that the mechanism responsible may be terminal fusion automixis, no males were produced, potentially indicating maternal sex chromosome hemizygosity WO.
These findings provide the first evidence of parthenogenesis in the family Boidae Boas , and suggest that WW females may be more common within basal reptilian lineages than previously assumed.