Despite having access to males, two female condors under conservation in the US have laid eggs without male condor fertilisation, thrilling scientists.
The largest flying bird in North America, the condor has a wingspan of approximately 3 metres and can soar up to an altitude of 4,500 metres. The endangered species has been under protection and observation through decades.
Scientists writing for the Journal for Heredity have found another remarkable feat by condor females: parthenogenesis. What this means is that females can lay eggs without genetic contribution from males.
Researchers with the San Diego Zoo Wildlife Alliance say genetic tests confirm the findings, The group says two baby males (referred to as ‘chicks’) that hatched in 2001 and 2009 from unfertilised eggs, were related to their mothers –– but neither chick was related to a male.
“Here, we report molecular genetic evidence for parthenogenetic development of two California condors (Gymnogyps californianus), a species of New World vulture in the Order Cathartiformes. The two individuals were produced by two different females, each of which was housed with a fertile male as part of the captive breeding program for species recovery,” the authors of the “Facultative Parthenogenesis in California Condors” article write.
The director of conservation genetics for the San Diego Zoo Wildlife Alliance and a co-author of the report, has called the recent findings a “eureka moment”.
“Many scientists have experiences like this when they see the world in a way they haven’t seen before,” says Oliver Ryder, who co-wrote the paper detailing the discovery, released in late October. “I was really pleased to figure out something that was such a conundrum.”
Condors have been in danger for a century. The Guardian says the European settlers in the West “often shot, poisoned and captured the condors, collected their eggs, and reduced their food supply of antelope, elk and other large wild animals” so much so that by 1982, only 22 specimens were left alive. But a state-led recovery programme has since successfully bred the animals back from near extinction.
According to VOA, “It is the first report of asexual reproduction in California condors.”
“Reproduction from an unfertilized egg can happen in other animals such as sharks and bees. But in birds, it usually only takes place when females are not around males. In this case, each mother condor had bred with males before. The two mothers involved in the research had produced 34 chicks. Each was with a fertile male condor at the zoo when they produced the eggs without male help.”
The case of the condors is unique because the researchers believe it is “ the first case of asexual reproduction in any bird species where the female had access to a mate.”
Condors in the wild were brought into the San Diego Zoo and its two captive breeding locations and were genetically tested to avoid inbreeding.
National Geographic notes that “California condors have been in decline about as long as European settlements began to spread across North America. These birds have been on the U.S. endangered species list since 1967 and were near extinction when their captive-breeding program began.”
Because they are scavengers, out in the wild they were susceptible to lead poisoning from lead-based ammunition. They are also slow to mature and slow to reproduce, with the female laying an egg once every two years.
According to another article, “[the theory that condors are using parthenogenesis as a survival tool] may not hold with the California condors. For one, the captive females that produced the male birds in question had access to mates. Secondly, neither of the offspring produced by parthenogenesis survived to reproduce itself. SB260 died after less than two years; SB517 died before reaching eight. In contrast, some California condors can live to a ripe old age of 60.”
Ryder tells the Guardian that even though parthenogenesis means “virgin birth” in the case of the condors “The idea that these are “virgin births” is incorrect … the females who reproduced this way had previously had many chicks through sexual reproduction. And birds don’t give birth; they lay eggs that hatch.”
“In their lifetimes, [the two chicks that were the product of parthenogenesis] weren’t even recognized to be parthenotes… we’re definitely keeping our eyes out anytime we get a batch of blood samples for testing,” Ryder tells Gizmodo.
“We only now have the genetic tools to look at this in detail,” Ryder says. “Previously, parthenogenesis was really identified by seeing females who weren’t housed with males have offspring. But now we know the condor can have offspring while being housed with males and it begs the question, ‘Is this going on more than we know?’”
Source: TRT World
‘A eureka moment’: Condors lay unfertilised eggs that produce offspring
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