Diliff viaWikimedia Commons//CC BY 2.5
You have intercourse the drill : When a male person and a female love life each other very much — or are compelled by nature — they make a infant together . But sometimes a female becomes significant without any input from a male person . So - called “ virginal births ” may seem miraculous , but they ’re actually the product ofparthenogenesis , a conformation of asexual reproduction in which an embryo grows and develops without fertilization .
Parthenogenesis has been observed in some invertebrates like honeybee and Scorpion , and very seldom among captive vertebrates like serpent , lizards , and bird . Now researcher at Stony Brook University say they’vediscoveredthe first have a go at it example of parthenogenesis in hazardous vertebrates — and the phenomenon could be more mutual than we think .
Named for what looks like a massive chain saw blade jut out out of its grimace , thesmalltooth sawfish , which lives in southerly Florida , was first listed as an jeopardize coinage in 2003 . Its phone number have been drastically thin thanks to overfishing and home ground loss . Andrew Fields , a PhD candidate at Stony Brook ’s School of Marine and Atmospheric Science , wanted to get a sensation of incisively how many sawfish still exist .
“ We wanted to be ready to say , ‘ This is happening , and we need to do something now before they go nonextant , ’ ” Fields toldmental_floss .
They may have set out to do a universe count , but they found much more . As they document inCurrent Biology , Fields and his team examine sawfish DNA for star sign of inbreeding , which can indicate a dwindling number of individuals in a species . In the process they discovered that about 3 percent of the sawfish they studied were solely the offspring of their mothers and had no genetical part from a male .
In normal intimate reproduction , the female egg ejects half its chromosomes through a series of jail cell division after it ripen , making up the difference by combining with the chromosomes from the virile spermatozoon . In virgin birth , another female cellular telephone known as the frigid body provides the 2nd one-half of chromosome . Although the offspring will have two sets of chromosome , they will be identical .
Perhaps even more surprising is that the fatherless sawfish seem relatively normal . “ We do n’t have any physical proof they ’re any different , which is strange because the worldwide possibility powerful now is [ that ] agamogenetic offspring are not primed , and so they do n’t live on in the wilderness , ” Fields says . “ So this is kind of a cock-a-hoop tone . ”
But why do “ virgin births ” come about ? Until now , sexless reproduction in vertebrate had only been observed in immurement , so the standing hypothesis has been that the special stresses of captivity are the movement , Fields say . In 2001 , for exercise , a hammerhead shark at a Nebraska zoogave birthdespite not have contact with a male person for three years .
But these new finding intimate that peradventure it ’s not the stress of being in immurement that prompts parthenogenesis , but a want of male person . Perhaps a virginal birth is a dwindle away species ’ last - ditch endeavor to avoid quenching .
alas for the sawfish , parthenogenesis probably wo n’t help keep the population alive . While the parthenogenetic fish seem normal , they are all female , which could worsen the problem of manly scarcity . “ If the sexuality ratio flips enough , it could help oneself with the extinction , ” Fields says .
Fields and his team are urge other researchers to conjoin the hunting for examples of virgin births in gaga craniate by reexamining be deoxyribonucleic acid evidence . “ A lot of shark populations have been fished for the shark fin trade , so it ’s potential we could start looking at a number of shark coinage , ” Fields says . “ It may be the data is out there , but nobody has looked for it because we think it does n’t chance . ”
[ h / tThe Guardian ]
