Biologists are looking at how a shark
in a Great Lakes region aquarium gave
"virgin birth" last year. Photo courtesy of
Belle Isle Aquarium, Detroit.
A female shark in an aquarium in the Great Lakes region has apparently given virgin birth. Four shark eggs hatched last year and three of those babies are now growing normally. As the Great Lakes Radio Consortium’s Celeste Headlee reports, it may be some time before the cause can be determined, but the event is still a surprise for biologists:
Transcript
A female shark in an aquarium in the Great Lakes region has apparently given virgin birth. Four
shark eggs hatched last year and three of those babies are now growing normally. As the Great
Lakes Radio Consortium’s Celeste Headlee reports, it may be some time before the cause can be
determined, but the event is still a surprise for biologists:
Biologists have a technical term for virgin birth. It’s called parthenogenesis. Doug Sweet is the
Curator of Fishes at the Belle Isle Aquarium in Detroit. He says parthenogenesis is common in
invertebrates and some amphibians.
“Most vertebrate animals, the females will produce eggs even if the male is not around. And it’s
just a matter of… it’s a chemical trick, basically, to get that egg to develop into an individual
without a sperm activating it.”
But parthenogenesis has been totally unheard of for sharks, until now. Last year, the Henry
Doorly Zoo in Omaha, Nebraska, announced they thought a Bonnethead shark there had
reproduced by parthenogenesis. The baby lived less than 12 hours, though, and genetic tests were
inconclusive.
But when Doug Sweet saw the press release from the Henry Doorly Zoo about a possible virgin
birth, he thought he’d try an experiment. Sweet decided to incubate the eggs of his two female
bamboo sharks. Four of the eggs developed. Sweet says the sharks were acquired by the
aquarium before they had reached sexual maturity, and they have never been exposed to a male.
He says the likely conclusion is that these sharks are reproducing by parthenogenesis.
Two other explanations, though highly unlikely, are that the shark has both testicular and ovarian
tissue, and fertilized its own eggs or that sharks are capable of storing sperm for years and even
passing it down to their offspring. Sweet has sent small clippings from the sharks’ fins to the
Henry Doorly Genetics Lab. Testing has already begun, but Sweet says it could take more than a
year to get the results. In the meantime, Sweet says the facts remain the same: a female shark
has given virgin birth. If it is parthenogenesis, he says, it will have important implications for
biologists around the world.
“Parthenogenesis just hasn’t been considered to happen in sharks; it’s never been recorded. It may
be happening all the time out there, so this is kind of breaking news in the shark world.”
The two adult bamboo sharks and the offspring are currently on exhibit at the Belle Isle
Aquarium in Detroit.
For the Great Lakes Radio Consortium, I’m Celeste Headlee.
People who do historic restoration have been taking advantage of cloning technology. Historic trees are being cloned to help preserve and restore historic landscapes. The Great Lakes Radio Consortium’s Tamar Charney reports:
Transcript
People who do historic restoration have been taking advantage of
cloning technology. Historic trees are being cloned to help preserve and
restore historic landscapes. The Great Lakes Radio Consortium’s Tamar
Charney reports:
Michigan’s Fort Mackinac is a military fortress from the American
Revolution. In the mid 1800’s, soldiers stationed there planted a row of eight
sugar maples lining the fort’s parade ground. But these trees are now old
and dying.
Phil Porter is a curator who’s worked at Fort Mackinac for over
30 years. He says he was sad and concerned that they would soon lose this
living link to the fort’s past. So he decided to have the trees cloned.
“We think that by cloning them, by going to that very high level of
reproducing what is there now we can do the most accurate job of
reproducing the environment, the right looking trees, and putting them
back in the same place.”
While the clones won’t look any different from a sugar maple seedling
bought at a nursery, keeping the genes of a historic tree alive through
cloning seems to appeal to people. There are tree cloning projects
underway in Massachusetts, Maryland, and even Australia to help replicate
historic trees people have a connection to.
For the Great Lakes Radio Consortium, I’m Tamar Charney.
New testing has found some of the most common cosmetic and beauty products contain chemicals linked to birth defects. The Great Lakes Radio Consortium’s Lester Graham has more:
Transcript
New testing found some of the most common cosmetic and beauty products contain chemicals linked to birth defects. The Great Lakes Radio Consortium’s Lester Graham has more:
Three environmental groups hired a major national laboratory to test 72 name-brand off-the-shelf beauty products for chemicals called phthalates. Of the 72, 52 of them contained phthalates. Jane Houlihan is with Environmental Working Group and one of the authors of the report on the testing…
“What this means for women is as they use cosmetics, they’re likely getting exposed to phthalates and it’s a potential concern for a baby in the womb, a male baby, since many of these chemicals are really strongly linked in animal studies to birth defects of the male
reproductive system.”
There is not yet a direct link between phthalates in cosmetics and reproductive birth defects in humans. The environmental groups found products on the market that don’t use the chemicals. So, they’re calling for elimination of the use of phthalates in beauty products.
For the Great Lakes Radio Consortium, this is Lester Graham.
A recent United Nations report indicates the earth’s population has doubled since 1960. The report says the result of that growth is that humans are altering the planet on an unprecedented scale. The Great Lakes Radio Consortium’s Lester Graham has the details:
Transcript
A recent United Nations report indicates the earth’s population has doubled since 1960. The report says the result of that growth is that humans are altering the planet on an unprecedented scale. The Great Lakes Radio Consortium’s Lester Graham reports.
In its report, the United Nations Population Fund said that with six-point-one billion people on earth, humans are using more resources than ever before. The report indicates rising affluence and consumption along with the growing population are combining to cause extensive environmental damage. The report explains that increasing population itself does not mean increasing damage to the environment. But to be sustainable where the population is growing fastest, Asia and Africa, those regions must have better access to outside resources and technology to better manage their own natural resources, and the political will to use them responsibly. Without the resources and political will, the report indicates that growing populations in undeveloped areas tend to strip the ground clear of natural resources as well as damage the environment and induce famine and disease. For the Great Lakes Radio Consortium, I’m Lester Graham.
In a narrow swath of
grass in a roadside ditch, a mallard hen nests her second brood of the
season, a rare event for these ducks. Her first ducklings were killed
by a predator.
Researchers Tina Yerkes
and John Simpson track the mallard hens by radio transmitters. They've
found many of the ducks are killed by agricultural pursuits such as
mowing. Lawnmowers can kill hens that
are nesting in grass.
John Simpson 'candles' an
egg, looking at the silhouette of the developing duckling to see how
near it is to hatching.
In the last decade or so, ducks in the Great Lakes region have not been reproducing as well as they have in the past. The number of ducklings hatching out and surviving to adults has dropped by about 25 percent. Researchers are trying to figure out why this is happening and what can be done about it. The Great Lakes Radio Consortium’s Lester Graham went into the field with researchers and has this report:
Transcript
In the last decade of so, ducks in the Great Lakes region have not been reproducing as well as they have in the past. The number of ducklings hatching out and surviving to adults has dropped by about twenty-five percent. Researchers are trying to figure out why this is happening, and what can be done about it. The Great Lakes Radio Consortium’s Lester Graham went into the field with researchers and has this report.
(sound of quack, quack overhead / cross fade to truck doors and engine startup/ bed of gravel sounds)
Mallard ducks are the most common duck found throughout the Great Lakes states. You’ll see them on farm ponds, college lagoons, and even in big city parks. But recently the mallard’s population hasn’t been growing as fast. The duck’s rate of reproduction has been falling off in the region since the mid-1980’s. Researchers with the sportsman’s conservation group, Ducks Unlimited, are involved in a three year study of mallards to find out why the ducks are not surviving in as great of numbers.
Tina Yerkes heads up the project. In a truck with something that looks like a TV antenna on top, fellow researcher John Simpson and she are in northwest Ohio, near Lake Erie, headed out to find some of the mallard hens. Tiny transmitters were surgically implanted in the ducks earlier this year and the antenna tracks the signals.
“So, this is the whole gizmo setup here. Everyday these guys go out and they track the birds. Each bird has a unique beep, if you will, uhm, a frequency. And that’s basically how we figure out what they’re doing. We started with 57 and you’re down to 38?
JS: Thirty-eight, roughly. And, eleven? JS: Twelve. Twelve have actually been killed, either by predators or farming operations on this site.”
(Truck sound under)
As the truck gets close to the last sighting of one of the mallard hens they’re tracking. John Simpson flips on the tracker and turns the antenna.
(beep beep sound)
He’s pulled over along a fairly busy road, and starts looking around in the roadside grass.
“So, she’s actually nesting in the ditch?”
“Yeah. I’m not entirely sure where her nest is here, so we’ve got to be careful.”
(sound of grass rustling)
It’s hard to believe a duck could find a place for a nest here. Most of the roadside is mowed except for a little strip of grass where we’re looking. She’s one lucky duck. A mower would kill her and destroy her nest.
“There she is right there. See her sitting on her nest?”
The mallard hen is three feet away and she’s still hard to see. John
Simpson has to flush her so that he can take a look at the eggs in the nest.
(Sound of flapping wings)
“There she goes.”
“She’s got a pile of eggs too. That’s her second nest.”
“That’s her second nest?”
“Yeah. She had a pile in her first nest.”
“Twelve eggs? Is that right?”
“Eleven.”
“Eleven?”
“Yep.”
(Ambience remains under)
The duck lost her first brood to a predator. Since she had nested close to a subdivision, it could have been a dog or cat. But the researchers say in this case it was probably a wild predator, maybe a raccoon.
“And, once we’re finished, we’ll just cover the nest so the predators don’t see it and we leave.”
It’s very rare that a mallard hen tries twice to raise a brood, But in this area the ducks are adopting a lot of unusual behaviors. Since there’s almost no grassland to nest in, hens have nested in hay fields where they’re usually killed at mowing time. One hen made a nest in a large flowerpot. At our next stop we found a duck in the backyard of a mobile home, and her eggs had just hatched.
(Peep, peep, peep of the ducklings)
The owner mowed around the duck’s nest, giving the mother and her eggs a chance to survive. Now that they’ve hatched, they’ll head to the water nearby. Tina Yerkes says development pressures have hurt the ducks here.
“In Ohio, we’re looking at pretty bad brood survival which tells us that probably we need to alter the landscape by putting wetlands back—by restoring wetlands and managed marshes for the broods. And then, probably also coupling that with some grassland habitat, ’cause as you can see, there’s not a lot of grassland habitat for them to nest in here. We need to improve that.”
The Ducks Unlimited researchers are getting some indications about what kinds of things are hurting the ducks ability to reproduce. Besides the loss of wetlands the researchers are finding that farming practices such as frequently mowing ditches and urban sprawl taking up grasslands are all contributing to a high mortality rate among ducklings and sitting hens. But the researchers haven’t collected enough information yet to make any solid conclusions. It’ll be two more years and many more sites before the Ducks Unlimited researchers have enough hard data.
Robert Payne is the Curator of Birds at the University of Michigan Museum of Zoology. He says while to researchers it might seem pretty clear that people are causing the lower rates of production in the duck population. Information like the Ducks Unlimited group is gathering will be helpful.
“Well, it seems to be common sense: the more people, the more development you have, the fewer places there are going to be for birds. But the people in our society who make the decisions like to have some data out there. (They) Like to know how many ducks, how much land, and so on. Otherwise, these people can’t really figure how much land the really should set aside for the ducks. No data, no well informed decisions.”
(sounds of birds and bullfrogs)
But some people might find data that are supposed to help ducks gathered by a group that’s chiefly supported by people who kill ducks for sport might be a bit of a conflict, or at least very self-serving. Ducks Unlimited researcher Tina Yerkes says there’s a larger purpose here than merely making hunters happy.
“The purpose is not necessarily to create more ducks to shoot, but the purpose is to alter and affect the landscape in a positive way for all the species that need the landscape. So, we’re trying to take a step back and determine what the wildlife needs and help put it back on the ground for the wildlife.”
Predictions are that the human population around the Great Lakes will steadily increase for the foreseeable future, and if the researchers’ early indications hold, it’ll likely affect the duck population even more. This study, when it’s complete, might give policy makers the information they need to find a balance between the needs of people and the needs of wildlife as the conflict between the two grows in the Great Lakes region.
For the Great Lakes Radio Consortium, this is Lester Graham.
Mallards are the most common duck in the Great Lakes region, but their numbers have been declining during the last few years. The Great Lakes Radio Consortium’s Lester Graham reports:
Transcript
Mallards are the most common duck in the Great Lakes region, but their numbers have been declining during the last few years. The Great Lakes Radio Consortium’s
Lester Graham reports.
The sportsmen’s conservation group, Ducks Unlimited is involved in a three year study, trying to learn why mallard duck populations are not increasing in the same numbers they once were. Tina Yerkes is a research biologist with the organization. She says starting in the mid-1950’s mallard flocks were growing at a pretty rapid rate.
“In the Great Lakes area, after the mid-80’s until now the production ratio has dropped and it’s dropped pretty sharply. And that for us is a warning bell, if you will, that something is going on in this area that’s causing birds not to do well.”
Yerkes and a team of biologists in Michigan, Wisconsin, and Ohio are tracking mallard hens and their broods. Early indications are that loss of habitat is beginning to affect the duck populations in the region. For the Great Lakes Radio Consortium, this is Lester Graham.
If you’ve ever had cockroaches, you know how hard it is to get rid
of them. Many people turn to exterminators or pesticide sprays. But
often, roach-killing products are made with neurotoxins that may be
harmful to pets and humans. Now, some scientists have come up with a
different approach: a kind of birth control… for cockroaches. The
Great
Lakes Radio Consortium’s Wendy Nelson explains:
Here’s something else to blame on El Nino. Because last
year’s winter was so mild, the zebra mussel population has exploded in
one Lake Superior port. The Great Lakes Radio Consortium’s Mike
Simonson has the story:
The U-S Environmental Protection Agency is working to identify whether certain chemicals disrupt human reproductive and neurological systems. The Great Lakes Radio Consortium’s Lester Graham reports that the process will take years, and for now, scientists recommend avoiding suspect chemicals found in some foods:
Bald eagles living near Lake Superior aren’t reproducing as frequentlyas those who nest on inland lakes. A new study blames the lack of foodrather than contaminated fish…and one of the study’s authors says policymakers should take note. The Great Lakes Radio Consortium’s ChuckQuirmbach has more:
Biologists are looking at how a shark in a Great Lakes region aquarium gave "virgin birth" last year. Photo courtesy of Belle Isle Aquarium, Detroit.
