More Marmorkrebs meetings in San Francisco

There will be a special session on Marmorkrebs at the next Society for Integrative and Comparative Biology meeting in San Francisco. It's not exactly a full blown regular symposium, so you won’t see it in the schedule yet. But it will be happening, and I will post more details as I learn them.

You can find more details about the meeting here.

Early registration for the meeting  closes 3 December. You can still register after that, but then prices go up.

Finish that crayfish paper!

Jim Fetzner, the managing editor for the journal Freshwater Crayfish, recently sent an email indicating that they are hoping to publish the next volume, number 19, in December.

The deadline for submissions for the next volume is 1 October 2012.

As noted before, the International Association of Astacology is making efforts to get this journal published more frequently. I applaud this, as having the journal on such irregular schedule that people don’t know whether it’s a journal, or conference proceedings, or something else, does nobody much good. But the journal will only improve if they get submissions.

As in the cage, so in the wild

Brian Switek (a.k.a. Laelaps) reports on a new case of parthenogenesis in the wild, in not one, but two species of snakes this time: copperheads and cottonmouths.

(I)n zoos and aquariums, zoologists have begun to document the strange phenomenon of facultative parthenogenesis: females of species that usually reproduce sexually, delivering offspring without mating. Surprise pregnancies have been documented among birds, sharks, snakes and Komodo dragons (Varanus komodoensis), but until now, only in captivity.

Very interesting stuff. Clearly some implications for the various reports of parthenogenesis in crayfish...

Human parthenogenesis?

I had no idea that in 1956, there was a claim of human parthenogenesis that was taken quite seriously. There was an article in The Lancet and everything.

The Telegraph has the story by Aarathi Prasad, “The modern-day virgin birth.” To this day, it is not clear how the girl, Monica Jones, was conceived, though Prasad has some speculations.

Hat tip to Jennifer Oullette.

Where are the Procambarus clarkii clones?

Some years back, a paper came out purporting to have identified genetically identical red swamp crayfish (Procambarus clarkii) in China (Yue et al. 2008). At the time, this was a rather remarkable claim, given that there have been no shortage of labs looking at this species. You would have expected that if P. clarkii could reproduce by parthenogenesis, someone would have noticed by now.

The plausibility of that claim went up, in my mind, with the discovery of facultative parthenogensis in spinycheek crayfish (Orconectes limosus). If Marmorkrebs and spinycheek crayfish, two species in different genera, could be parthengenetic, it seemed plausible that there was more reproductive flexibility than we thought in crayfish. And we’ve been caught off guard with other well studied species being facultative parthenogens.

The likelihood of P. clarkii clones has, in my mind, gone back down again with the publication of a new paper by Li and colleagues. In a study looking at the genes of P. clarkii across China, they found no evidence of genetically identical organisms. In fact, they say the exact opposite:

All the P. clarkii populations in China showed relatively high genetic diversity(.)

In some ways, the papers are broadly comparable in their methods: both are using cytochrome oxidase (COI) genes and microsattelites. But it is fair to say that the new paper may not have found clones because that wasn’t what they had set up their experiment to find. This paper is very much interested in the red swamp crayfish as an invasive species, which meant sampling across a wide geographic range. The previous paper by Yue et al. (2008) sampled more individuals at fewer collection sites. Intensive sampling at a small number of locations would be much more likely to detect genetically identical individuals.

The claim of parthenogenetic P. clarkii still needs confirmation. The best way would be to have an identified, isolated parent in the lab and DNA genotyping of both parent and offspring.

And I’m still waiting for confirmation of whether there are Marmorkrebs in China!

Reference

Li Y, Guo X, Cao X, Deng W, Luo W, Wang W. 2012. Population genetic structure and post-establishment dispersal patterns of the red swamp crayfish Procambarus clarkii in China. PLoS ONE 7(7): e40652. 10.1371/journal.pone.0040652

Yue GH, Wang GL, Zhu BQ, Wang CM, Zhu ZY, Lo LC. 2008. Discovery of four natural clones in a crayfish species Procambarus clarkii. International Journal of Biological Sciences 4(5):279-282. http://www.biolsci.org/v04p0279.htm

Faulkes and colleagues, 2012

Faulkes Z, Feria TP, Muñoz J. 2012. Do Marmorkrebs, Procambarus fallax f. virginalis, threaten freshwater Japanese ecosystems? Aquatic Biosystems 8: 13. http://dx.doi.org/10.1186/2046-9063-8-13

Abstract

Background

One marbled crayfish, Marmorkrebs, Procambarus fallax f. virginalis (Hagen, 1870), was discovered in a natural ecosystem in Japan in 2006. Because Marmorkrebs are parthenogenetic, they could establish a population from only a single individual, and thus pose a risk for becoming established in Japan, as they have in other countries. There are two major reasons to be concerned about the possibility of Marmorkrebs establishing viable populations in Japan. First, Japan’s only endemic crayfish, Cambaroides japonicus (De Haan, 1841), lives throughout Hokkaido and is endangered. Introduced Marmorkrebs are potential competitors that could further threaten C. japonicus. Second, Marmorkrebs live in rice paddies in Madagascar and consume rice. Marmorkrebs populations could reduce rice yields in Japan.

Results

We created five models in MaxEnt of the potential distribution of Marmorkrebs in Japan. All models showed eastern Honshu, Shikoku and Kyushu contain suitable habitats for Marmorkrebs. Hokkaido, the main habitat for C. japonicus, contained much less suitable habitat in most models, but is where the only Marmorkrebs in Japan to date was found.

Conclusions

Marmorkrebs appear to be capable of establishing populations in Japan if introduced. They appear to pose minimal threat to C. japonicus, but may negatively affect rice production.

Keywords: None provided.

Mięsikowski and colleagues, 2012

Mięsikowski M, Napiórkowska T, Templin J, Wilczyńska B. 2012. Embryonic development of Marmokrebs (Procambarus fallax forma virginalis, Hagen 1870). Acta Biologica Cracoviensia Series Botanica 54(suppl. 1): 69. http://www.ib.uj.edu.pl/abc/pdf/suppl54_1/sup_54_s1.pdf#page=33 (Conference abstract only)

Abstract

Marmokrebs (sic) are very interesting objects of study because of the possibility of parthenogenetic development. Attention was paid to him in the 90s the last century when a German pet shops came as breeding animal. Currently, the wild population of this crayfish exist in Eastern Europe, North America, Madagascar and Japan (Jones et al., 2008; Faulkes, 2010). This species due to the specific way of reproduction, high fecundity, small food selectivity and ease of adaptation to different environmental conditions is treated as a potentially invasive species. It is believed that it could threaten like native populations of aquatic invertebrates and fish (Scholtz et al., 2003).

Research on development of marmokreb (sic) were conducted in laboratory conditions in an aquarium with a capacity of 90 liters. In each breeding aquarium was placed on three females. After laid eggs the females were transferred to a separate tank. Water temperature which kept incubation female was about 22°C and pH 7.90–8.15. In order to observe the successive stages of development were taken from the incubating female three eggs every 12 hours. It was made biometric measurements of embryos and photographed the next stages of development.

It was found that the breeding conditions Procambarus fallax development take about 30 days. Eggs have spherical shape with diameter of 1.5 mm. Identified 10 embryonic stages, which coincide with the observations of Alweys (sic) & Scholtz (2006).

Keywords: None provided.

Note: Contrary to the above, there are no known wild populations of Marmorkrebs in North American or Japan.