31 May 2011

Another (occasionally) parthenogenetic crayfish

ResearchBlogging.orgI not sure how to describe the sound I made when I saw the title of this paper, but it was not a quiet sound. I immediately thought, “This is huge.”

A new paper in PLoS ONE reports that spinycheek crayfish (Orconectes limosus) can reproduce by parthenogenesis. Unlike a previous report of red swamp crayfish (Procambarus clarkii) reproducing by parthenogenesis, which based its claim on similar DNA from adults and no actual observed instances of reproduction, this paper claims to have isolated females that have reproduced.

The animals were taken from the wild and reared as adults, which immediately makes one think “sperm storage.” The authors argue that the genetic similarity of the offspring rules this out. I think an obvious next step is to see if juveniles born in the lab without sex can be reared through an entire generation, and in turn produce more offspring without meeting males.

This is a bombshell. It suggests that asexual reproduction in crayfish is more common than thought, particularly when the P. clarkii paper is also hinting that they can do the same. From an evolutionary point of view, this would mean that the evolution of the completely asexual lineage of Marmorkrebs may not have been as insurmountable as it first appeared.


Buřič M, Hulák M, Kouba A, Petrusek A, Kozák P. 2011. A successful crayfish invader is capable of facultative parthenogenesis: a novel reproductive mode in decapod crustaceans. PLoS ONE 6(5): e20281. http://dx.doi.org/10.1371%2Fjournal.pone.0020281

Picture from here.


Based on picture here.

24 May 2011

Filipová and colleagues, 2011

Filipová L, Grandjean F, Chucholl C, Soes DM, Petrusek A. 2011. Identification of exotic North American crayfish in Europe by DNA barcoding. Knowledge and Management of Aquatic Ecosystems 401: 11. http://dx.doi.org/10.1051/kmae/2011025


Several alien crayfish of North American origin have become established in Europe in recent decades, but their identification is often confusing. Our aim was to verify the taxonomic status of their European populations by DNA barcoding. We sequenced the cytochrome c oxidase subunit I (COI) gene fragment of individuals representing all American crayfish known from European waters, and compared the results with reference sequences from North America. Our results confirm the morphological identification of Orconectes juvenilis from a population in eastern France, and of the marbled crayfish (Marmorkrebs), i.e., a parthenogenetic form of Procambarus fallax, from south-western Germany. Sequences of most individuals of presumed Procambarus acutus from the Netherlands were similar to American P. cf. acutus, but one was divergent, closer to a sequence of a reference individual of P. cf. zonangulus. However, divergences among three American P. cf. zonangulus samples were also high, comparable to interspecific variation within cambarid species complexes. The divergence between O. immunis from Europe and America also reached values corresponding to those observed among distinct Orconectes species. Genetic variation in the American range of these crayfish should therefore be further studied. Our study shows that DNA barcoding is useful for the rapid and accurate identification of exotic crayfish in Europe, and also provides insights into overall variation within these taxa.

Keywords: COI • barcoding • invasive crayfish • Europe • North America • OrconectesProcambarus

17 May 2011

Dot com

I’m embarrassed to admit that once in a while, I wasn’t able to get to my own website on the first try.

If you live in North America and type in a domain name, what do you normally do after you get to the dot? You start typing “com”. It’s easy to forget about other domain names like “net” or “org” entirely.

But I won’t have that problem any more. And neither will anyone else. The Marmorkrebs website can now be reached by through Marmorkrebs.com.

Photo by RambergMediaImages on Flickr; used under a Creative Commons license.

11 May 2011

5th Annual Arthropod Genomics Symposium

If you’re quick, you still have time to submit a poster to the “Arthropod Genomics 2011: Exploring Diversity, Relating Similarity” symposium! The deadline for poster abstracts and registration is 18 May.

The symposium is being hosted by the Arthropod Genomics Center at Kansas State University.

10 May 2011

Celebrate diversity: Instant whiptail!

The origin of Marmorkrebs is still unknown. Hybridization of two species in aquaria has sometimes been tossed around as a potential hypothesis. It has some plausibility, given that almost every parthenogenetic vertebrate seems to trace back to a hybridization event. A new paper would seem to make the hybridization hypothesis slightly more plausible.

I’ve written before about whiptail lizards, the first multicellular animals I learned of that reproduced by parthenogenesis.

A paper in press by Aracely and colleagues describes the latest research on these animals: make a new, self-sustaining, hybrid from scratch. And the experiment was a success! The picture shows the hybrid in the middle of the two parental species. The hybrids have been reared through multiple generations in the lab, so this is not just a one-off event.

I can’t provide better coverage than Ed Yong does at Not Exactly Rocket Science. More coverage at Ars Technica.

The most remarkable thing about the publication of this success is that it comes only a year after another paper described a 29 nine year effort to do exactly this (Cole et al. 2010), without success.

Knowing that something is possible and has happened in nature doesn’t mean that it is likely to happen in the lab while we’re looking.


Lutes AA, Baumann BP, Neaves WB, Baumann P. 2011. Laboratory synthesis of an independently reproducing vertebrate species. Proceedings of the National Academy of Sciences 108(24): 9910-9915. http://dx.doi.org/10.1073/pnas.1102811108

Cole CJ, Hardy LM, Dessauer HC, Taylor HL, Townsend CR. 2010. Laboratory hybridization among North American whiptail lizards, including Aspidoscelis inornata arizonae × A. tigris marmorata (Squamata: Teiidae), ancestors of unisexual clones in nature. American Museum Novitates 3698: 1-43. http://hdl.handle.net/2246/6085

03 May 2011

Pic of the moment: 3 May 2011

Picture from here.