Facultative Parthenogenesis in California Condors.

Area of Science:

• Avian Biology
• Conservation Genetics
• Reproductive Biology

Background:

• Parthenogenesis is a rare mode of asexual reproduction documented in various vertebrate taxa, but infrequently observed in birds.
• Previous avian parthenogenesis cases involved females without male access, making facultative parthenogenesis in the presence of males a significant gap in understanding.

Purpose of the Study:

• To investigate and confirm instances of parthenogenesis in the critically endangered California condor (Gymnogyps californianus).
• To provide the first molecular marker-based evidence of facultative parthenogenesis in an avian species, particularly in females housed with fertile males.

Main Methods:

• Parentage analysis was conducted on two California condor eggs exhibiting parthenogenetic development.
• Polymorphic microsatellite loci were utilized to assess genetic contributions from both parents.
• Sex chromosomes and genetic markers were analyzed to confirm maternal inheritance and exclude paternal contribution.

Main Results:

• Two instances of parthenogenetic development were identified in eggs from two California condor females within a captive breeding program.
• Paternal genetic contribution was definitively excluded for both offspring.
• Both parthenotes were confirmed to have male ZZ sex chromosomes and were homozygous for all evaluated markers inherited from their dams.

Conclusions:

• These findings represent the first molecularly confirmed cases of facultative parthenogenesis in the California condor, a critically endangered avian species.
• The study demonstrates that parthenogenesis can occur in avian females even when housed continuously with reproductively capable males.
• This discovery broadens the phylogenetic understanding of vertebrate asexual reproduction and has implications for conservation breeding programs.