- Canada to further cut international student, foreign worker permits
- YouTube launches new TV-focused tools for creators
- White Sox heading for worst season in MLB history
- China the top challenge in US history: senior diplomat
- Hong Kong democracy tycoon's son warns time running out
- New migraine drugs no better than cheap painkillers: big study
- Sean 'Diddy' Combs again denied bail in sex trafficking case
- Brewers clinch division title as MLB playoff race heats up
- Man City blunted by 'giant' Inter in Champions League stalemate
- US stocks dip despite larger Fed interest rate cut
- Man City held by Inter as PSG pinch win in Champions League
- All Blacks recall Beauden Barrett for Australia Test
- Fears of all-out war as new Lebanon device blasts kill 20, wound 450
- Spurs late show saves Postecoglou blushes at Coventry
- PSG snatch late goal to beat Champions League debutants Girona
- Gittens' late double gives Dortmund Champions League win at Brugge
- Man City blunted by Inter in Champions League stalemate
- Hidden talent: French Olympic star Marchand opts for disguise
- MrBeast named in California lawsuit over 'Beast Games' show
- Gauff splits with Gilbert as coach after 14-month run
- Hundreds of thousands at risk in Sudan's El-Fasher: UN
- Harvey Weinstein pleads not guilty to new sex crime charge
- Venezuelan opposition candidate says letter conceding election was coerced
- Ukraine official claims Russian advance in Kursk has been 'stopped'
- X update allows app to bypass Brazil ban: internet providers
- Fears of all-out war as new Lebanon device blasts kill 14, wound 450
- US Fed makes aggressive rate cut, weeks before election
- Arsenal's Odegaard faces lengthy injury absence
- India coal expansion risks massive methane growth: report
- China the top challenge in US history, top diplomat says
- US Fed makes larger half-point cut in first reduction since 2020
- Ronaldo's Al Nassr appoint former AC Milan boss Pioli
- Ainslie 'relieved' as British book place in Louis Vuitton Cup final
- Struggling Roma replace sacked icon De Rossi with Ivan Juric
- Women's NBA will add 15th team in Portland in 2026
- Brazil fires need harsher punishment: environmental police boss
- Boeing to start large temporary furloughs amid Seattle strike
- Fears of all-out war as new Lebanon device blasts kill nine, wound 300
- 'Emergency' declared over falling UK butterfly numbers
- McIlroy outlines threats to golf peace deal
- Stock markets, dollar slip before US rate decision
- Russian advance in Kursk 'stopped': Ukraine official to AFP
- UN members demand end to 'unlawful' Israeli occupation of Palestinian territories
- Snapchat pushes 'safer' platform image, but not everyone agrees
- Three dead, 100 wounded in new wave of Lebanon device explosions
- So where does the oceans' plastic waste come from?
- Allied war heroes buried in Netherlands... 80 years on
- Marsh coy over Australia's choice to open alongside Head
- New London sculpture pays tribute to trans community
- Lebanon doctors tell of horror after pager blasts
RBGPF | 5.79% | 60.5 | $ | |
GSK | -0.31% | 42.43 | $ | |
RIO | -0.02% | 62.91 | $ | |
BTI | -0.34% | 37.88 | $ | |
RYCEF | 1.37% | 6.55 | $ | |
NGG | -0.46% | 70.05 | $ | |
CMSC | 0.02% | 25.055 | $ | |
SCS | 0.71% | 14.11 | $ | |
BCC | 1.33% | 137.06 | $ | |
CMSD | -0.12% | 24.98 | $ | |
AZN | 0.06% | 78.58 | $ | |
RELX | -0.82% | 47.37 | $ | |
VOD | 0.49% | 10.23 | $ | |
JRI | 0.45% | 13.44 | $ | |
BP | -0.37% | 32.43 | $ | |
BCE | 3.09% | 35.61 | $ |
Inbreeding won't doom the last of the vaquitas, but fishing might: study
Vaquita porpoises are on the edge of extinction, with just 10 left in their sole habibat within Mexico's Gulf of California.
However, a new study published Thursday in the journal Science offers some hope: the world's rarest marine mammals aren't doomed by a lack of genetic diversity, and can recover if illegal "gillnet" fishing ceases immediately.
"We're trying to push back on this idea that there's no hope, that nothing we do could save them at this point. It's just not an accurate assumption," lead author Jacqueline Robinson of the University of California San Francisco told AFP.
Porpoises are closely related to dolphins, and share many things in common including great intelligence.
The vaquita, whose name means "little cow" in Spanish, measures four to five feet (about 1.5 meters) in length, making it the smallest of all cetaceans.
Shy and elusive, they are known for distinctive dark circles around their eyes, and relatively large dorsal fins, which are thought to help them dissipate heat in their warm habitat.
Vaquita numbers were decimated in the 20th century as a result of being accidentally trapped and drowning in gillnets: long walls of nets hanging in open water that are used to catch fish and shrimp.
Fishermen sought in particular the totoaba, a large fish about the size of the vaquita, whose swim-bladder is prized in traditional Chinese medicine.
The totoaba itself is endangered and its fishing is illegal, but the ban isn't always respected.
The vaquita's historical abundance was unknown, but by the time of the first survey, in 1997, only around 570 remained.
There were fears that harmful mutations among the surviving vaquitas could seal the species' fate due to inevitable inbreeding.
To find out whether that was the case, the researchers analyzed the genomes of 20 vaquitas that lived between 1985 and 2017, and discovered that over the past 250,000 years their population had never exceeded a few thousand.
They also learned that their genetic diversity had always been low, relative to other cetacean species such as dolphins, orcas, and other whales.
- Benefits to low genetic diversity -
"Generally, we would think of low genetic diversity as being a bad thing. But in this case, it is somewhat advantageous for the vaquitas for their possibility of future recovery," said Robinson.
Inbreeding increases the chances offspring will inherit two copies of harmful mutations, leading to genetic disorders.
But it turned out that the frequency of these mutations are very low in vaquitas to begin with, because the population has always been small.
"So those mutations were historically weeded out much more effectively, than in a larger population, where those mutations could persist and remain hidden from natural selection," explained Robinson.
There are other species that appear more resistant to so-called "inbreeding depression," including mountain gorillas and narwhals, for similar reasons.
The team then carried out simulations to forecast the species' future.
Encouragingly, there is only a six percent chance of vaquitas' extinction if gillnet fishing is eliminated.
But if such fishing is only reduced, then the extinction risk rises drastically.
Even with an 80 percent reduction in fishing, the porpoises have a 62 percent chance of disappearing.
"While we now know that the species' ability to recover is not limited by their genetics, vaquitas have very little time left," said co-author Christopher Kyriazis of the University of California, Los Angeles, in a statement.
"If we lose them, it would be the result of our human choices, not inherent genetic factors."
S.Keller--BTB