Molecular markers contribute to a breeding programme of the extinct-in-the-wild Alagoas Curassow Mitu mitu and confirm the validity of the species

Abstract

Alagoas Curassow Mitu mitu is considered extinct in the wild, having previously inhabited a small area in north-eastern Brazil that has since been replaced by sugar cane farms. Around 50 birds possessing morphological features of this species are still alive in captivity in Brazil, all being descendants from a breeding programme started in 1979, using offspring from a single male and two females captured from the wild. However, this captive population also includes some hybrids with the congeneric Razor-billed Curassow M. tuberosa and their descendants. Furthermore, the validity of Alagoas Curassow as a species is questionable. We used two molecular markers to study the validity of this taxon as a species, to detect potential hybrids present in the stock, and to estimate genetic variability among the remnant specimens. The analysis of 760 base pairs from mitochondrial cytochrome b and control region sequences revealed that at least three of the 20 birds analysed had sequences identical to those of Razor-billed Curassow. The other 17 birds presented sequences that diverged 2.6% from Razor-billed Curassow. Moreover, a sample from an Alagoas Curassow museum skin collected from the wild in 1951 had cytochrome b sequences identical to those of the 17 birds. These results confirm the Alagoas Curassow as a valid species. DNA fingerprinting profiles of the 20 descendants from the Alagoas Curassow breeding population showed that this group of birds is depauperate in genetic variability. There was an increase in genetic variability of birds born after 1990, attributed to the hybrid mating of Alagoas Curassow with Razor-billed Curassow. We suggest that birds born before 1990 should be handled separately from the others. However, if a decrease in chick harvest among birds of this group is detected due to inbreeding depression or ageing, cross-breeding between this group and the group of birds most closely related to it should be considered in order to enrich the progeny with the Alagoas Curassow genome.