Snail Sex

U of I professors slimed for their snail research
Thomas O'Donnell
Iowa Science Interface


At first, it may sound completely ridiculous: a four-year, $876,000 grant from the federal National Science Foundation (NSF) to study “snail sex.”

That’s how a conservative news website branded it – wrongly. And it’s how two University of Iowa researchers and their California colleague found themselves at the center of the latest debate on government’s role in supporting basic science research, a debate that started with a similar attack on duck penis research.

If you don’t believe this is a big deal, type “snail sex” into your favorite search engine. Since March 27, when the conservative news (and I use that term advisedly) website CNSNews.com posted the item, numerous right-wing blogs and commentators have scorned the investigation as an example of wasteful government spending. Other bloggers have defended the research and the researchers, U of I biology professors Maurine Neiman and John Logsdon and Jeffrey Boore, an adjunct professor at the University of California, Berkeley, and chief executive officer of Genome Project Solutions, Inc.

Snail sex came up on HBO’s Real Time with Bill Maher in a debate about science and the federal deficit. Zack Kopplin, who made a case for basic science research on that program, also defended the U of I snail project on the NPR Science Friday program last week.

The “snail sex” kerfuffle came just a week after CNSNews.com posted a similar item about a Yale University study of waterfowl genitalia that instantly became known as the “duck penis research.” It, too, set off a wave of outrage and a similar outpouring of defenders. The researcher in question, Patricia Brennan, even issued her own response in a Salon article.

Logsdon, who’s received NSF support before, wasn’t too shocked when conservatives targeted the snail project. Having grown up in the years of William Proxmire’s attention-getting Golden Fleece Award, he said, he’s wondered when his research into sex among organisms like tiny protists and rotifers would get this kind of attention.

But he’s disappointed no one bothered to ask him or Neiman about it. “Even though this thing has gone semiviral, it’s perhaps not surprising that there’s been nearly no follow-up with the researchers here.”

Neiman said the extent of her contact with the press was an email from the CNSNews reporter. Under the guise of writing an article about the federal sequester’s effects on science research, he asked her to confirm the amount of the grant. “I said, ‘Yup, that’s it,’” Neiman said. She later got a call from a Fox network reporter with the same question. “Not that my expectations are high for the conservative press,” she adds, “but there was zero effort on their part” to understand the science and its implications.

The press and the bloggerati have kicked the issue around for more than two weeks, but I’m the only writer who’s asked the Iowa professors to explain their research.

At the heart of the outrage is the perception, as Logsdon said, that President Barack Obama is writing them a check. (Of course, in previous years it would have been President George W. Bush writing the checks.)

The reality is that this and other grants are awarded competitively. Panels of scientists in the same or similar fields review each proposal anonymously, weighing them against dozens of others. Recent NSF statistics show that it funded only about a fifth of the proposals made to its Molecular and Cellular Biosciences program in the Directorate of Biological Sciences, the program that funded Neiman and Logsdon. The fact that experts and the NSF chose the snail research indicates that questions about sex’s advantages are important and the project is well designed to get at answers.

If other media outlets had taken a deeper look at the NSF proposal, they might have seen how the snail project addresses some of the most fundamental, persistent questions of biology and evolution, with ramifications for human health and the environment.

This is not about why or how snails have sex. It’s about why any species has sex.

In essence, biologists have long been puzzled by why organisms developed sexual reproduction. Sexual reproduction is costly in time and energy. Asexual reproduction (essentially an organism cloning itself) is more efficient. And sexual reproduction also generally isn’t in an organism’s biological interest because it means passing on only half its genes.

“Theory suggests that sex must be beneficial because sexual females waste half of their reproductive investment on offspring that themselves cannot reproduce directly: males. In other words, such a costly trait as sex would not be so common if it didn’t confer profound benefits,” Neiman and Logsdon wrote in an email.

So what genetic and evolutionary advantages does sexual reproduction offer? The theory is that it provides genetic diversity and counters the propagation of harmful mutations. But sexual reproduction also can produce harmful mutations and, anyway, where’s the genetic proof of sexual reproduction’s advantages?

Researchers have put forth hypothetical conditions under which sex can succeed, but “we are still a long way from collecting the data that allow us to rigorously test these hypotheses,” Neiman and Logsdon wrote. That’s what their research is about.

The models scientists typically have used to study reproduction, like fruit flies (sexual) or yeasts (asexual), are inadequate because you can’t compare genetic information from sexual and asexual organisms in species with the same genetic backgrounds.

That’s where Potamopyrgus antipodarum comes in. This New Zealand snail has two lineages, one that reproduces sexually and one that reproduces asexually. While the species typically reproduces sexually, occasionally a female will asexually create a daughter, for unknown reasons the team hopes to explore. Those daughters and their offspring reproduce asexually only, creating two genetic lines the researchers can compare.

Despite the headlines about “snail sex,” Neiman, Logsdon and Boore aren’t peering into snail bedrooms like nonvertebrate fetishists (although the Iowa researchers say there are reasons to study behavior, too). They’re using the latest gene-reading technology to study the DNA of the different snails and compare them. They’re looking at how the genomes of sexually reproducing snails compare with those that reproduce asexually. By observing how mutations accumulate and genes are preserved or lost, they hope to get at the real, fundamental reasons for or against sexual reproduction.

Most of the NSF money is going into compiling and comparing snail DNA sequences, Neiman and Logsdon said, but a lot also is spent training high school, undergraduate and graduate students and early-career researchers. They learn to compile and analyze genomic data, skills that will enable them to continue on the path to discovery.

And some grant money goes to engage the community, with water quality workshops and collaboration with tenth-grade biology students at a local high school. The students are helping develop and test curricula to teach thousands of other students about biology and genomics.

The research could provide other benefits. The team says P. antipodarum could be a powerful model for other biological questions, including host-parasite dynamics (important to preventing a devastating disease in developing countries). The snails are a problematic invasive species around the world, so learning more about them also could help find strategies to reduce their populations.

P. antipodarum also could be important to ecotoxicology, which addresses pollution’s impact on the environment and human health. For instance, Neiman said, estrogens are an increasing concern in water supplies. The New Zealand snails are especially sensitive to these hormones, which cause them to reproduce more. Monitoring snail populations could provide an early warning of estrogen contamination in lakes and ponds.

Because the snails live at the bottom of lakes, they also could provide clues to contamination from heavy metals and other pollutants. A complete genome for the species could be useful in understanding contaminants’ effects.

The researchers also think the snails could help understand the consequences of chromosome loss, since P. antipodarum often gains or loses single chromosomes. Chromosome loss is a major concern in human health, Neiman and Logsdon say, as a primary cause of infertility and cancer and the source of Down syndrome.

These are only a few possible applications for their research, Logsdon said, but there are more yet to be discovered. That’s the thing about basic research: It provides the kind of knowledge and serendipitous discoveries that lead to breakthroughs.

For example, another U of I researcher studying lung disease in humans contacted Neiman out of the blue, seeking more information about her snail research. “There may be important parallels between the mucus and cilia that characterize lung cells and the mucus and cilia that characterize snail movement,” she wrote in her email to me. The researchers plan to meet soon.

It’s a nascent connection, but, Logsdon said, “It’s an example of how we really can’t predict” how basic research will connect to other subjects. “It’s one reason we need to learn about the diversity of life” beyond humans.

Even given all this, Neiman understands the public’s hesitancy about supporting basic research. “I’m happy to have a conversation about how we should invest” tax dollars, she said, especially in a difficult economy. “I’m very sympathetic to the public wanting to understand how basic science works,” because there’s clearly a misperception – as their case shows.

In a future post, I’ll share my thoughts about the snail firestorm.

Wow, yeah its about genetic diversity, d-duh! Sorry man, that was so much fluff to just to even begin to get to the point thats as far as i got lol. I can go no further!!

Clearly an unbiased and unsympathetic piece lol. Not sure if the main point was to try to make a point or just bash the conservative media, which i dare not defend on the whole.

Pun wrote:Wow, yeah its about genetic diversity, d-duh! Sorry man, that was so much fluff to just to even begin to get to the point thats as far as i got lol. I can go no further!!

How do you know its all about genetic diversity? We've assumed that that is the case, however I don't know that the idea has been tested. While mating with another organism does increase diversity more rapidly than asexual reproduction, it also requires more energy (finding a mate) and does not come with any grantee of a return on energy expenditure (you spend all your time trying to impress a mate but get rejected). Biodiversity can and has been achieved through asexual reproduction, as evidenced by bacteria and viruses (ever wonder why there is a new flue shot every year?).

Pun wrote:Clearly an unbiased and unsympathetic piece lol. Not sure if the main point was to try to make a point or just bash the conservative media, which i dare not defend on the whole.

I think the author made a valid observation. Many "conservative" (please forgive me for the use Marc) news outlets, politicians, and activists have historically made a point of attacking valid science and scientists.

While there are several in the scientific community that hold economically conservative ideals and even some who have socially conservative world views, very few scientists vote Republican. The reason? The GOP has made a very nasty habit of denying valid science and vilifying scientists (and really all intellectuals) in an attempt to score points with a more base demographic or to avoid conflicts with party dogma. Now those scientists who don't agree with the Democratic platform stay home on voting day or vote third party (I have a few friends who voted Libertarian, despite the fact they had no chance of winning).

Without genetic diversity, there can be no genetic mutations, no evolution. And i would have told them that for half the price!

This is why even with many asexual creatures, some will morph into males and they will breed all in order to share genetic material. This is nothing new as far as i know

Pun wrote:Without genetic diversity, there can be no genetic mutations, no evolution. And i would have told them that for half the price!

What!? You can take a single bacteria, let it split and replicate for several generations, and then see differences in the different cell's DNA, despite the fact they all originated from the same cell. If what you said was true, we wouldn't a) have more than one species on Earth and b) need to keep making new antibiotics to deal with mutated bacteria.

Pun wrote:This is why even with many asexual creatures, some will morph into males and they will breed all in order to share genetic material. This is nothing new as far as i know

If you reproduce asexually, then you couldn't morph into male or female. There are some species who's sex can change throughout their lives, however their mode of reproduction is not asexual. Asexual reproduction means that you, without needing to interact with any other organisms, can generate offspring. Bacteria do this by literally splitting in half.

Right your right, but again unless this all just a figment of my imagination, there are some species that, without outside genetic material, do create clones of themselves, but on occassion switch to sexual reproduction. As for the bacteria question, you know evolution takes far longer than a few generations. Actually, if what YOU said were true we would only have one microbial species on earth, if cloning was the way to go. Everything we already have studied and know about animal life is that genetic diversity is important to the carrying on of genes, some of which mutate over time to create new species. S'all im saying. I dont think we need another government funded study to figure that out

Pun wrote:Right your right, but again unless this all just a figment of my imagination, there are some species that, without outside genetic material, do create clones of themselves, but on occassion switch to sexual reproduction. As for the bacteria question, you know evolution takes far longer than a few generations. Actually, if what YOU said were true we would only have one microbial species on earth, if cloning was the way to go. Everything we already have studied and know about animal life is that genetic diversity is important to the carrying on of genes, some of which mutate over time to create new species. S'all im saying. I dont think we need another government funded study to figure that out

I apologize for failing to articulate my point clearly. What I was arguing is that you can get genetic diversity through asexual reproduction, however the mode of generating diversity (both good, bad, or benign) is genetic mutation. You start out with one microbe, then it splits. When this happens the 'offspring' may or may not be genetically identical to the 'parent,' or there might have been a small glitch in the copying of DNA that results in some changes. If changes occur that are beneficial or benign the organism survives to split and reproduce, if the trait is detrimental it may not survive long enough to produce offspring.

While you are correct in noting that evolution is seen across several generations, it is important to note that with bacteria a generation spans a very short period of time. Under good conditions, as one would create in a lab, a cell could split into two in less than ten minutes. By this, once could achieve 144 generations in a day. Also assuming that the population starts out as one lone organism that can replicate its self in 10 minutes, and assuming that all offspring live to split, we can predict the size of the population at the end of one day (1440 minutes) using N(t)=Nºe^(kt) where N(t) is the population at time t, Nº is the initial population (1) , and k is the rate of growth. Thus:

N(t)=(1)e^((0.2 cell/min)(1440 min))
N(t)=(1)e^(288)
N(t)=1.19x10^125 cells

So after one day we would have had 1.19E125 chances for mutations to take place.

Also just want to point out the immunity benefits of sexual reproduction, and crossing genes everytime an individual is created, rather than some random %. Either way, i think nature knows the way to go

Would you guys fund this project?

"Limits on Cosmic Radio Bursts with Microsecond Time Scales."