A tiny fraction of vertebrate species have ever been seen reproducing through parthenogenesis, the fatherless birth of offspring in which the embryo develops without fertilization by a male. Now you can add boa constrictors to that short list: A study in Biology Letters documents the case of a boa that gave birth to 22 offspring over the last two years, all of whom are female and born this unusual way.
“Only with the development and application of molecular tools have we truly begun to understand how common this form of reproduction may be,” lead author Warren Booth [says]. Booth, a research associate at North Carolina State University’s Department of Entomology, and his team first suspected something was up when the mother boa constrictor gave birth, twice, to a total of 22 caramel-colored females. The males housed with the female did not carry the gene for this recessive color trait. [Discovery News]
When Booth’s team analyzed the DNA of the young snakes, they found no evidence of paternity by any of the males who’d mated with their mother previously. Furthermore, the chromosomes of the 22 young gave them away.