Endangered California condors can reproduce asexually, study finds
>>Claire Fahy, The New York Times
Published: 31 Oct 2021 10:24 AM BdST Updated: 31 Oct 2021 11:54 AM BdST
-
A Reuters infographic on a wildfire that threatened California condors in July, 2008
Conservation geneticists working to preserve endangered California condors have discovered two instances of chicks hatching from unfertilised eggs — the first known cases of so-called virgin births within the species.
That finding, included in a study published Thursday in The Journal of Heredity, is particularly remarkable, as such cases are unusual among birds.
Parthenogenesis, the process by which female animals produce embryos that have not been fertilised by sperm, is more common among vertebrate species like fish or lizards. Before the findings made public Thursday, the other known instances of parthenogenesis among birds were limited to turkeys, finches and domestic pigeons, according to the San Diego Zoo Wildlife Alliance.
“Parthenogenesis is considered to be a rare phenomenon in birds,” said Oliver Ryder, a co-author of the study and director of conservation genetics at the San Diego Zoo Wildlife Alliance. “We discovered it in California condors because we have such a detailed genealogical analysis of the entire population.”
California condors have long been an endangered species, with the world population falling to just 23 in 1982, according to the US Fish and Wildlife Service. At that point, the agency pulled all the known California condors out of the wild and bred them in captivity.
The species, which in 2020 numbered 504 birds, has been closely monitored and studied for decades, leading to discoveries like the one published Thursday, said Samantha Wisely, a conservation geneticist at the University of Florida who was not involved in the study.
The need to identify the birds by sex in order to develop a successful breeding program led to the discovery about the two chicks.
Years ago, Ryder was asked to develop a system for identifying the sex of the California condors in captivity because males and females look the same. He also had to identify close relatives among the birds so that relatives would not be paired. So he created a genetic database for all California condors.
In 2013, Ryder’s team noticed some discrepancies in the database, which prompted a new analysis of all the birds in captivity. Ryder’s team discovered two male chicks — one born in 2001, the other in 2009 — that didn’t match any of the males’ genetic profiles. That meant that none of the male condors had fathered them.
“There was no paternal contribution,” Ryder said. “They had only genetic information from their mothers.”
The final clue that these chicks had developed from parthenogenesis was the fact that both were male. Because of the birds’ genetic makeup, female condors reproducing on their own can give birth only to male condors.
In the past, parthenogenesis has been thought of as a somewhat desperate form of reproduction, occurring when females were in low-male populations or in environments with few members of their own species, Wisely said.
The condors in captivity, however, had been paired with males in an enclosure, yet still reproduced through parthenogenesis.
According to Ryder, the discovery of “virgin births” in such a closely monitored bird population is leading scientists to wonder whether more birds in the wild are reproducing through parthenogenesis than previously believed.
“For other species it seems to be sort of a last-ditch effort to save themselves,” Wisely said. “It will be really interesting to know the context in which it’s happening in the wild for birds.”
Another interesting aspect of parthenogenesis is that lethal genetic traits cannot be passed down from the mother. Still, Ryder said, some less favorable traits may still appear in the offspring.
“Maybe they could, you know, not carry the good-looking genes or something,” he said.
©2021 The New York Times Company
-
Wild elephant moved to Dulahazra safari park
-
Exhausted, wild elephant prefers humans
-
An anaconda’s play date with dolphins took a strange turn
-
20% of reptiles risk extinction
-
Dozens of bald eagles have died from bird flu
-
Why are Kangaroos turning up in India?
-
Fossil holds clues to how some owls evolved
-
Can these revered cranes survive without humans?
-
Rescued wild elephant moved to Sheikh Mujib Safari Park in Dulahazra for treatment
-
Exhausted, weak wild elephant prefers to stay close to humans
-
An anaconda’s play date with dolphins took a strange turn
-
From king cobras to geckos, 20% of reptiles risk extinction
-
Dozens of bald eagles have died from bird flu
-
Why are Kangaroos turning up in India?
Most Read
- Bangladesh announces Padma bridge tolls, a step closer to inauguration
- Exhausted, weak wild elephant prefers to stay close to humans
- Bangladesh Bank devalues taka again as US dollar hits record high
- Dollar surges past Tk 100, but still ‘hard to find’
- Azovstal siege ends as hundreds of Ukrainian fighters surrender
- US police say college student Zinat’s death was a suicide. Her family disagrees
- India's top court revokes ban on large prayer gatherings in mosque
- PM Hasina urges restraint amid surging commodity prices in global markets: Mannan
- ‘It’s not like exchanging Christmas cards’: envoy says India will follow legal process for PK Halder extradition
- North South University is ordered to sell luxury cars for research spending