New rules?

HR669 hasn’t exactly been making national headlines, but in certain circles, has been the topic of much discussion. Sponsored by Guam delegate Madeleine Bordallo (pictured), it’s going to be the subject of an American congressional subcommittee hearing this week (23 April 2009).

The summary of the bill indicates that much is expected in determining whether a species would be allowed in the country or not, including the identity of the organism to the species level and the native range of the species.

Of course, Marmorkrebs would pose a potentially interesting enforcement conundrum. It has no formal species description. It has no known native range – but its closets relative appear to be southern U.S. species. Are Marmorkrebs nonnative?

GrrlScientist has several posts about this new bill (first, second, third).

There are literally tens of thousands of species of non-native birds, mammals, reptiles, amphibians, fish and invertebrates that are kept and bred in the United States (for example, there are more than 2,500 species of non-native freshwater and marine fish species in the aquarium trade alone).

In particular, she is asking researchers for information about whether this would impact their research.

Mike Dunford chimes in here and has a follow-up here.

Rare, threatened, or endangered?

I was listening to an interview with Sarah Pryke on The Science Show. She works with beautiful Gouldian finches (a gallery of them is here). It came up in the conversation that she has about 2,000 of these birds. She estimates that this may well be equal to the number of these birds left in the wild. Which is one of those astonishing thoughts. We forget how many species have most, if not all, of their populations essentially reliant on humans keeping them.

What do you call an animal with no known original wild population? “Extirpated”? No, that’s not quite right. “Extinct in the wild”? That assumes that there is an identified wild population. Regardless, an organism that had known no endemic territory left would be surely be worthy of a conservation effort, wouldn’t it?

Of course, Marmorkrebs fall into such category. We don’t know if they have a home besides our aquaria, or whether it’s under threat or how many Marmorkrebs there might be.

I’ve written a fair amount about Marmorkrebs’ potential to be an invasive species. And while they’ve been introduced into the wild, in Madagascar and elsewhere, but it is far too early to tell what the outcome there will be. If anything, there should probably be some efforts to try to control them in places like Madagascar, because they so obviously don’t belong there.

Nevertheless, it is worth considering the idea that Marmorkrebs might actually be rare, in the global sense. Unless we find a wild population – and there are some reasons to suspect that one might not exist – their future might depend on humans.

And being in that situation has rarely worked out well for the organisms concerned.

23 Squidoo

Marmorkrebs are now featured on a Squidoo lens and The Aquarium Wiki.

I find it fascinating how the picture I uploaded for Wikipedia makes its way elsewhere around the web.

Market organisms?

Science magazine last week featured a book review of the first volume of Emerging Model Organisms. Since this is what I hope Marmorkrebs to be, I looked at this with great interest. And luckily, author Jonathan Slack did make some instructive comments on what makes for a successful model organism.

A model organism must exemplify some key general biological problem that can be solved relatively easily with it and that will turn out to have the same answer for more important but experimentally less tractable organisms, namely human beings or economically important domestic animals and crop plants.

Because I’m a neurobiologist, my opinion may be skewed, but it seems to me that crayfish serve well for general biological problems related to nervous system organization and function, as I hope I show my irregular series, “Great Moments in Crayfish Research.” So, in a sense, Marmorkrebs is not entirely a new model organism, but a variation that can take advantage of new questions (e.g., evo-devo) and methodologies (e.g., transgenics). Marmorkrebs do also serve as a model for “economically important animals,” namely other large decapod crustaceans like lobsters and crayfish, whose rearing is less convenient.

The book's protocols reveal that not all the aspirant models are capable of being bred in the lab—something I would consider a basic requirement.

And that’s a point in Marmorkrebs favour, though I’ll be the first to admit that the fairly long generation time and a few related concerns are issues.

For those who manage science funding, the book should pose the question: How many model organisms do we need? That issue is all the more urgent because there is a second volume of this series looming, so there will soon be another 20 or so organisms wanting to get their snouts, tentacles, probosci, or roots into the trough. We practitioners of academic life sciences feel we require a doubling of total expenditure about every five years to remain reasonably comfortable. Funding bodies have found this a difficult target to meet, and it will become even harder with so many more model organisms to feed.

I added the emphasis, because the statement is one that I have never seen before. It’s not clear to me if he’s talking about individual researchers, a research lab, a research field, or something else. But I’ll take a stab at replying to Slack’s rhetorical question with one of my own.

How many more Drosophila researchers do we need? Or mouse? Or C. elegans? Or E. coli?

Now, I am not criticizing anyone who works on those organisms. I know a lot of those people, and I like a lot of those people, and appreciate the science that they do. But the recruitment of researchers to existing model organisms resembles what Jorge Cham called a “Profzi scheme,” where more and more people are working on fewer and fewer organisms.

Perhaps a lesson can be taken from ecology rather than economy. In ecology, it’s often the case that there are advantages to being rare.

References

Slack JMW. 2009. Emerging market organisms. Science 323(5922): 1674-1675. doi: 10.1126/science.1171948

Various authors. 2009. Emerging Model Organisms, A Laboratory Manual, Volume 1.
Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY. ISBN 9780879698263. ISBN 9780879698720. http://cshprotocols.cshlp.org/emo/

Perspective on a problem

Madagascar has been mentioned several times in this blog because Marmorkrebs have been introduced into the wild there. Sadly, an invasive crayfish species is currently a very small problem for researchers and others concerned with the island. The country is in turmoil politically.

Sadly, there political situation is spilling over into research and conservation issues. A suite of conservation groups have issued a statement that describes the current conservation situation:

Open and organized plundering, sometimes using firearms, of precious wood from several natural forests, including national parks such as Marojejy and Masoala, which have been declared World Heritage Sites.

Intensified smuggling of wild species, especially reptiles such as tortoises, to the national and international markets.

Proliferation, due to the current impunity, of destructive practices such as illegal mining and slash-and-burn agriculture within protected areas and environmentally sensitive areas.

Great moments in crayfish research: Serotonin, octopamine, and social status

The paper is usually remembered as using lobsters, probably because many of the later papers springing from it used lobsters. But there were crayfish in there too, and I have the photographic evidence to prove it.


These two pictures show good old Louisiana red swamp crayfish, Procambarus clarkii, the lab rat of the crustacean world. The animal on the left is in a pose that would normally be associated with an aggressive animal, one gearing up for a fight. The animal on the right is in a pose that would normally be associated with, “Please don’t kill me.”

Crayfish fighting has been consistently studied for over half a century (Bovbjerg 1956 is a seminal paper), and are a fairly well used model for aggression. There are many reasons for this, but one is that crayfish will fight early, often, and for no reason. They fight when they are small, so the behaviour is completely “hard wired.” They fight if there is no food, shelter, or mating opportunities at stake. Fighting is just something they do.

Now, we normally think of fighting as a fairly complicated behaviour. You have to assess your opponent. Make tactical decisions to continue on the fight or leave. Thus, you would think that finding a way “into the system” would be quite tricky.

That’s where the experiment pictured above comes in. The crayfish shown are not animals that are in a fight. instead, they have been injected with the neuroactive chemicals. The individual on the left has been injected with serotonin (also known as 5-hydroxytryptamine, or 5-HT). The individual on the right has been injected with octopamine.

What looked to be a potentially intractable problem involving many neurons was simplified and made tractable at a stroke. It now appeared that crayfish – and other similar decapod crustaceans – had a couple of fairly simple “master dials” on their behavioural control panel relating to aggression and social status. And those fairly simple dials were things that experimenters could use to fiddle with the system. Finding out that simple injection of these chemicals mimicked some important aspects of fighting behaviour paved the way for many later papers.

References

Bovbjerg RV. 1956. Some factors affecting aggressive behaviour in crayfish. Physiological Zoology 29: 127–136.

Livingstone MS, Harris-Warrick RM, Kravitz EA. 1980. Serotonin and octopamine produce opposite postures in lobsters. Science 208(4439): 76-79. doi: 10.1126/science.208.4439.76

Losing sex

A forthcoming article in Trends in Ecology & Evolution (a.k.a. TREE) looks at the problem of detecting whether an organism reproduces sexually or asexually. This might seem to be a trivial problem, but it isn’t. For one, many organisms are poorly studied. And we are starting to discover that some organisms can switch between sexual and asexual reproduction.

Komodo dragons provide a good example of the latter. Because they are “charismatic megafauna” (they’re the biggest lizards in the world, and we love biggest and smallest things), there’s no shortage of people looking at them and maintaining them in zoos. But it was only a few years ago that it was found that females could also reproduce asexually (Watts et al. 2006).

In the TREE article, Schurko and collegues list four ways that an asexually reproducing species, like Marmorkrebs, can originate.

• Hybridization: Many asexual species appear to be the result of interbreeding between two different sexual species. Just by virtue of how many parthenogens are thought to be hybrids, this might be the number one contender for the origin of Marmorkrebs.


• Spontaneously: You get an unlucky (or lucky, depending on your point of view) genetic change, either through a mutation or anomalous gamete formation.


• Infectious: Some bacteria, most famously Wolbachia, can influence the reproduction of hosts they infect, and can dramatically skew sex ratios.


• Contagious: I’m not 100% clear how this one works, but involves the spread of “asexual genes.” The reference given is a crustacean case, Daphnia pulex (Innes & Hebert 1988).

It’s a completely open question at this point which of these four possibilities led to the formation of Marmorkrebs. But knowing the range of possibilities is important in figuring out ways of testing those hypotheses.

References

Innes DJ, Hebert PDN. 1988. The origin and genetic basis of obligate parthenogenesis in Daphnia pulex. Evolution 42(5): 1024-1035

Schurko AM, Neiman M, Logsdon JM Jr. 2009. Signs of sex: what we know and how we know it. Trends in Ecology & Evolution: in press. http://dx.doi.org/10.1016/j.tree.2008.11.010

Watts PC, Buley KR, Sanderson S, Boardman W, Ciofi C, Gibson R. 2006. Parthenogenesis in Komodo dragons. Nature 444(7122): 1021-1022. http://dx.doi.org/10.1038/4441021a