Archive for Sex and Reproduction

Hen mothers for ducklings, cross-fostering species

// August 25th, 2011 // 1 Comment » // Sex and Reproduction

hen and ducklings

Image by cod_gabriel

When I was young and living on a small farm in the Adelaide Hills, we used to raise ducklings under chickens. The hens were more inclined to sit and warm the eggs, and once hatched were better at protecting their young from rats. So we took duck eggs, placed them under brooding hens, and everything was cheery.

Those hens loved them little ducks, at least, they looked after them just as well as they did their own chicks. They’d go out foraging together, chattering away in their different tongues at a handful of scattered grain. But there was one place where their differences became obvious. The pond.

At the first sight of water, the ducklings would be in and swimming, having a great time duck-diving underwater and eating duckweed. Meanwhile, mother hen would be going absolutely spare! You could almost hear the concerned clucks saying “now get out of that water at once! Don’t you know you can’t swim? Oh heavens, what have I done to deserve such unruly children?”

What she’d done, somewhat unintentionally, was to be a cross-foster mother. A species which raises children of another species.

Peahen and guineafowl chicks

Image by Chicago Zoological Society

Chicago’s Brookfield Zoo recently raised two clutches of guineafowl chicks with peahen mothers. The parents protected their brood from hawks, and showed them the ropes of living free-range in the zoo – such as how to avoid pedestrians.

From the press release:

“‘Zoogoers may not notice anything unusual between the moms and chicks, but there are definitely differences and several barriers that they needed to overcome, including language and behaviors,’ said Tim Snyder, curator of birds for the Chicago Zoological Society, which manages Brookfield Zoo. ‘The first two weeks were a little precarious because the chicks needed to learn what the peahens’ vocalization meant and adapt to different behaviors that are not instinctual to them.’

“For instance, Guineafowl chicks naturally scatter and hide when frightened or threatened, while peachicks run toward their mother. Additionally, Guineafowl moms and chicks move as a group and help care for each others’ young, which is the opposite of independent peafowl.”

Black Robin on Rangatira Island

Image by Frances Schmechel

Cross-fostering for conservation helped bring Black Robins from the brink of extinction. In 1980, only five survived in the wild on Little Mangere island in New Zealand, including a just one fertile female called Old Blue.

Each Spring, the first clutch of eggs was raised under a Chatham Island tit, giving Old Blue time to breed twice in the season.

Bit by bit the population has crawled back and is now a relatively comfortable 250 individuals. The fostering program has been used as a model for other endangered bird species.

The red queen, sex and nematode worms

// July 28th, 2011 // 1 Comment » // Recent Research, Sex and Reproduction

Alice_and_Red_Queen

Alice and the Red Queen by John Tenniel

In Lewis Carroll’s Through the looking-glass– a whacky book if I ever read one – the laws of physics don’t really apply. Hills can become valleys, straight can become curvy, and forward is really backward.

In one scene, Alice chases after the Red Queen, both running as fast as they can, but when they stop Alice realises they are still right where they started. “Now, here, you see, it takes all the running you can do to keep in the same place” says the Red Queen.

And it might be the same with the evolution of predator and prey, host and parasite. Running doesn’t get you anywhere. So says the Red Queen Hypothesis.

c elegans embryo

C elegans embryo. Image by Monica Gotta

As the host adapts to fight the parasite, the parasite evolves to infect the host. It’s an endless race, and extinction faces the first organism to stop running.

So what’s this got to do with sex? Sex is evolution on turbo. Mixing and matching genes increases genetic diversity, giving a species more opportunities to outlast in the ultimate game of survivor.

Field data supports the Red Queen Hypothesis as describing an adaptive advantage of sex. Models and maths support the idea that coevolving species could select for rare genes and unusual combination randomly created by sex. Direct experimentation of coevolution and nookie is tricky business.

New research, published in Science, grew several populations of nematode worms (C. elegans, roundworms) which are usually asexually, but reproduce sexually 20% of the time.

The populations were differently exposed to bacterial parasites (Serratia marcescens) as shown.

C Elegans Sex Research

C Elegans image by Bob Goldstein, University of Carolina, Chapel Hill, remixed by Science Journal. Creative Commons License

One population was given the parasites and left to their own devices. They and their bacteria could evolve together. These nematode worms increased their rate of sexual reproduction to 80-90% over time, and maintained a high level of sexy-times.

The other nematodes were given frozen stocks of bacteria every generation, so the parasites weren’t evolving as the worms did. At first, sexual reproduction increased in the worms, but then it dropped back down to 20% – the same level as nematodes which hadn’t been exposed to the bacteria at all.Alice meets dodo

Parasites on their own don’t increase sex – coevolution does.

A second experiment supported their conclusion. Nematodes mutated to be unable to reproduce sexually (asexual obligates) became extinct after 20 generations when exposed to the parasites. But mutants that always required sex to reproduce (sexual obligates) never became extinct.

When it comes to coevolution, it’s fall behind and be left behind.

Never stop running.

ResearchBlogging.org

Morran, L. et al (2011). Running with the Red Queen: Host-Parasite Coevolution Selects for Biparental Sex Science, 333 (6039), 216-218 DOI: 10.1126/science.1206360
Brockhurst, M. (2011). Sex, Death, and the Red Queen Science, 333 (6039), 166-167 DOI: 10.1126/science.1209420

Sex and mosquitoes – transmitting the Zika virus

// April 8th, 2011 // 5 Comments » // Recent Research, Sex and Reproduction

Senegal. Image by Mathieu Dammon

When Brian Foy returned home to America from a field trip in Senegal, Africa, he didn’t know he was infected with the mosquito spread Zika virus.

But just a few days later he was sick with extreme fatigue and joint pain, and so was his wife Chilson. A new study coauthored by the pair and colleagues suggests that this is the first documented case of an insect-borne disease being transmitted sexually.

Though the paper lists the patients as Anonymous, in an interview to Science Brian revealed he was patient 1, and his wife was patient 3.

The lucky person who was patient 2 was Brian’s PhD student Kevin Kobylinski, who had been collecting mosquitoes with him as part of his malaria research. Being bitten came with the job, so they were vaccinated against some of the major disease, including Dengue fever.

The symptoms, when they arrived, seemed to suggest they had nonetheless caught Dengue fever. Headaches, torso rashes and fatigue all round lasting for a week, then muscle pains which lingered longer. They sent blood samples to the U.S. Centers for Disease Control and Prevention, who ran a number of antibody tests. The tests showed that all three had antibodies against Zika virus, which infects monkeys and humans in Africa and Asia.

But Brian’s wife, Chilson, has never travelled to Africa or Asia. The cool climate of Colorado supports different mosquito species to those tropical varieties which spread Zika. In fact, Zika had never been recorded in the Western Hemisphere.

They concluded that Zika had been transmitted human to human, and probably sexually, as their four children didn’t get the disease.

If Zika virus can be spread by sexual transmission, it could change the way the disease is prevented. Zika is considered an emerging pathogen, having infected about 70% of the people on Yap Island in the Pacific during 2007.

ResearchBlogging.orgFoy, B. (2011). Probable Non–Vector-borne Transmission of Zika Virus, Colorado, USA Emerging Infectious Diseases DOI: 10.3201/eid1705.101939 (pdf)

Super cute kittens conceived by science

// March 18th, 2011 // 2 Comments » // Recent Research, Sex and Reproduction

african black-footed kitten

African black-footed kitten conceived by IVF

This little kitty is a rare African black-footed cat conceived through IVF in an attempt to keep the species alive.

About 40 of these cats live in zoos worldwide, while a few wild cats live in South Africa where they are protected, but sometimes poisoned and killed by farmers.

How could you poison these little kittens, they’re so CUTE!!! Ahem. So, I have been visiting Zooborns again, it’s a serious habit.

Let’s pretend this post is about something more than just cute pictures of cats, and talk about the science that conceived them.

Audubon Center for Research of Endangered Species aim to protect seriously endangered species by creating a “frozen zoo”, banking genetic material such as eggs, sperm, embryos and tissue samples. Frozen, thawed sperm and IVF technology sparked the life of these kittens, which were really conceived six years ago and frozen as embryos.

The embryos were thawed and implanted into the surrogate mother Bijou in December last year.

african black-footed cat

Man, what did I DO last night?

It must be a bizarre experience for the mother, although I’ve heard tomcats have a barbed penis so perhaps she’s lucky to have skipped the usual event.

The frozen zoo contains frozen semen from the gorilla, Sumatran tiger, jaguar, Jabiru stork, and caracal. Other cell samples cover the African and Asian elephants, Baird’s tapir, colobus monkey, roan antelope, and black bear.

“The next step for us will be to clone the black-footed cat and transfer the embryo to a domestic cat surrogate,” said Audubon Center for Research of Endangered Species Senior Scientist Dr. C. Earle Pope in the media release.

Cloning endangered species, is that a good idea or not? I can’t tell.

Genographics, Neanderthals and Cannibalism, an Interview with Carles Lalueza-Fox

// December 8th, 2010 // 1 Comment » // Recent Research, Science Communication, Sex and Reproduction

After the event last night about the worldwide Genographic Project, I caught up with Prof Dr Carles Lalueza‑Fox, the first speaker on the night, for a quick interview. He’s an expert on Neanderthals, or Neandertals I think we call them now. Named after the Neander Valley where the first specimen was discovered.

What first sparked your interest in studying Neandertals?

When the first Neandertal sequence was retrieved in 1997 I had been working on ancient DNA for a while, but then Neandertals seemed to be something in a different league.

In the first ten years it was only possible to get mitochondrial DNA from Neandertals.

For me, I really liked Neandertals and human evolution as a child. Ancient DNA was something particularly difficult at the time, and the thing that brought me to the subject.

How human do you think Neandertals were?

How human?

Yes, tricky question.

Haha, yes. It’s a very long question, a very difficult question. One must always take into mind our tendencies are always fluctuating. We saw them as a very primitive human lineage in the early 20th Century, but I’d say that now we’re turning to the point where we see them as very similar to us.

Maybe the best thing to think about Neandertals is they are more different from us than any modern human to any other modern human. That’s the way we should think about them.

If we want to think of them as a different species that’s fine for me, but there is a range of difference between us and the Neandertals.

The cuts found along Neandertal bones you suggest are evidence for cannibalism. Could they just be an example of de-fleshing prior to burial?

Well, yeah, it might be right in some circumstances. But this is not only cutting, you know de-fleshing the bones. It’s also fragmenting the bones with small stone tools, very small fragments, and even the skull, and the faces. For me it’s very difficult to think that this kind of post mortem activity is something more because this is a complete destruction of the bones.

It’s very similar to what we see in other sites with fauna, the bones are broken to extract the marrow in the same way.

And it’s a pretty common thing, well, not common these days, but certainly we humans have our own history of cannibalism.

Yes, well there are several sites with the signs in Neandertals. But you almost think that life was very tough and they were structured in very small groups, so the fact that you find another one… I mean you’d say “hey, we are Neandertals all of us,” but I’d say that’s a modern conception.

Whereas for them it might be “hey, you’re not one of my family I may as well eat you.”

Yeah, the idea of humankind, in fact, is very recent. After the second World War, and the UNESCO thing. So even the idea of humankind is more recent than we might think now.

And what do you think of the possibility of Neandertals and humans mating?

I think it’s plausible with the data we have. It was probably something that was a minority, restricted in time and space, it was nothing important in my view. The thing is we can detect it now in non-African modern humans is because this was an expanding population, so even a small event of just a few, say it was, this was amplified later on.






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