17 June 2015

Classical crays

I’m always fascinated by what music people think go with what animals. From here.

03 June 2015

International Symposium on Conservation of Native European Freshwater Crayfish

the International Symposium on Conservation of Native European Freshwater Crayfish will be held in Olot, Girona (Spain) from 23-25 September 2015. Registration has been extended to 15 July 2015.

The conservation of native crayfish is one of the major challenges in European inland waters, since most species are endangered by many factors, but specifically by introduced species and pests. This symposium will focus on recent research advances, and also on management strategies and specific experiences focused to achieve a long-term conservation of our native freshwater decapods.

Wesbite: http://www.crayfishsymposiumlifepotamofauna.org/

Email: lifepotamofauna@consorcidelestany.org

01 June 2015

Celebrate diversity: What the sawfish saw

Welcome the latest member of the parthenogenetic club, the smalltooth sawfish!

This case is interesting not only because it adds yet another case of facultative parthenogenesis to the list, but because it’s one of the few times facultative parthenogensis has been seen in wild populations. The bad news is that this might be because the sawfish is endangered: the population is so low that the fish are resorting to “last gasp” reproductive efforts.

A “boo” to this Miami Herald article, though, for confusing the religious doctrines of immaculate conception (conceived without original sin) with virgin birth (conceived without a father).

Hat tip to David Shiffman.


Fields AT, Feldheim KA, Poulakis GR, Chapman DD. 2015. Facultative parthenogenesis in a critically endangered wild vertebrate. Current Biology 25(11): R446-R447. http://dx.doi.org/10.1016/j.cub.2015.04.018

External links

Virgins gone wild
Father, son and holy sawfish! Researchers find ‘virgin birth’ in Florida endangered species 
Sawfish spawn without sex
Sawfish escape extinction through 'virgin births', scientists discover

Picture by Anna Pang on Flickr; used under a Creative Commons license.

13 May 2015

Vogt, 2015

Vogt G. 2015. Stochastic developmental variation, an epigenetic source of phenotypic diversity with far-reaching biological consequences. Journal of Biosciences 40(1): 159-204. http://dx.doi.org/10.1007/s12038-015-9506-8


This article reviews the production of different phenotypes from the same genotype in the same environment by stochastic cellular events, nonlinear mechanisms during patterning and morphogenesis, and probabilistic self-reinforcing circuitries in the adult life. These aspects of phenotypic variation are summarized under the term ‘stochastic developmental variation’ (SDV) in the following. In the past, SDV has been viewed primarily as a nuisance, impairing laboratory experiments, pharmaceutical testing, and true-to-type breeding. This article also emphasizes the positive biological effects of SDV and discusses implications for genotype-to-phenotype mapping, biological individuation, ecology, evolution, and applied biology. There is strong evidence from experiments with genetically identical organisms performed in narrowly standardized laboratory set-ups that SDV is a source of phenotypic variation in its own right aside from genetic variation and environmental variation. It is obviously mediated by molecular and higher-order epigenetic mechanisms. Comparison of SDV in animals, plants, fungi, protists, bacteria, archaeans, and viruses suggests that it is a ubiquitous and phylogenetically old phenomenon. In animals, it is usually smallest for morphometric traits and highest for life history traits and behaviour. SDV is thought to contribute to phenotypic diversity in all populations but is particularly relevant for asexually reproducing and genetically impoverished populations, where it generates individuality despite genetic uniformity. In each generation, SDV produces a range of phenotypes around a well-adapted target phenotype, which is interpreted as a bet-hedging strategy to cope with the unpredictability of dynamic environments. At least some manifestations of SDV are heritable, adaptable, selectable, and evolvable, and therefore, SDV may be seen as a hitherto overlooked evolution factor. SDV is also relevant for husbandry, agriculture, and medicine because most pathogens are asexuals that exploit this third source of phenotypic variation to modify infectivity and resistance to antibiotics. Since SDV affects all types of organisms and almost all aspects of life, it urgently requires more intense research and a better integration into biological thinking.

Keywords: clonal organisms • development • ecology • epigenetics • evolution • genotype-to-phenotype mapping • individuality • infectivity and resistance • phenotypic variation • stochasticity

Mrugała and colleagues

Mrugała A, Kozubíková-Balcarová E, Chucholl C, Cabanillas Resino S, Viljamaa-Dirks S, Vukić J, Petrusek A. 2015. Trade of ornamental crayfish in Europe as a possible introduction pathway for important crustacean diseases: crayfish plague and white spot syndrome. Biological Invasions 17(5): 1313-1326. http://dx.doi.org/10.1007/s10530-014-0795-x


Rapidly growing trade of ornamental animals may represent an entry pathway for emerging pathogens; this may concern freshwater crayfish that are increasingly popular pets. Infected crayfish and contaminated water from aquaria may be released to open waters, thus endangering native crustacean fauna. We tested whether various non-European crayfish species available in the pet trade in Germany and the Czech Republic are carriers of two significant crustacean pathogens, the crayfish plague agent Aphanomyces astaci and the white spot syndrome virus (WSSV). The former infects primarily freshwater crayfish (causing substantial losses in native European species), the latter is particularly known for economic losses in shrimp aquacultures. We screened 242 individuals of 19 North American and Australasian crayfish taxa (the identity of which was validated by DNA barcoding) for these pathogens, using molecular methods recommended by the World Organisation for Animal Health. A. astaci DNA was detected in eight American and one Australian crayfish species, comprising in total 27 % of screened batches. Furthermore, viability of A. astaci was confirmed by its isolation to axenic cultures from three host taxa, including the parthenogenetic invader Marmorkrebs (Procambarus fallax f. virginalis). In contrast, WSSV was only confirmed in three individuals of Australian Cherax quadricarinatus. Despite modest prevalence of detected infections, our results demonstrate the potential of disease entry and spread through this pathway, and should be considered if any trade regulations are imposed. Our study highlights the need for screening for pathogens in the ornamental trade as one of the steps to prevent the transmission of emerging diseases to wildlife.

Keywords: aquarium trade • exotic pathogens • Aphanomyces astaci • white spot syndrome virus • Marmorkrebs • DNA barcoding

14 April 2015


Last month, I finally manage to watch a show for which I’d heard many positive things:Orphan Black.

If you have not see it, I highly recommend this show. I’m writing about it here on this blog because the show is about genetically identical females – much like Marmorkrebs.

There are so many striking things about this show. The performance of lead actress Tatiana Maslany is astonishing. But as a biologist, I was struck by how sophisticated the portrayal of the science is. The show is fortunate to have a very good scientific consultant, Cosima Herter, who shares a first name with one of the lead characters.

The show’s take on clones stands in a stark contrast to many other depictions of clones in pop culture. Whereas most stories emphasize the similarities of the clones, Orphan Black runs the opposite way, and hammers away at the differences of the women in the show. The individual characterization is so complete and so well thought through and so consistent that you continually forget that it is all performed by one person. (Two if you count the body double Kathryn Alexandre).

It reminded me of my post from several years ago about how one of the great things about Marmorkrebs was that you could see the differences between sisters that started with the same identical genetic materials.

As I thought about it, another recent show also emphasized that clones were individuals: Star Wars: The Clone Wars series. As the series progressed, it gave the clone troopers names. Different haircuts. Different insignia. In short, the clones stopped being interchangeable cannon fodder and became distinct characters.

Do these shows reflect a larger cultural shift in our thinking about how genetics affects our identities? Too soon to tell, but I find the different portrayals of genetically identical individuals fascinating.

A new season of Orphan Black starts this weekend. And I can’t wait.

Related posts

How Marmorkrebs can make the world a better place

External links

Meet the real Cosima, Orphan Black's science consultant: The Crazy Science Of Orphan Black

The real life science behind Orphan Black
The many faces of Tatiana Maslany
Meet The Woman (Besides Tatiana Maslany) Who Plays Every Single "Orphan Black" Clone

07 April 2015

Marmorkrebs: the Early Years

Chris Lukhaup was one of the co-authors of the paper that introduced Marmorkrebs to the scientific world (Scholtz et al. 2003). He has been active in describing many new species of crustaceans, often emerging from the pet trade (for example, Lukhaup & Pekny 2006, 2008). He takes stunning pictures. He recently contacted me with this bit of history about Marmorkrebs, which I share with his permission (lightly edited):

When I contacted Jay Huner in Louisiana back in 2000 to tell him that I believe that the Marmorkrebs is a parthenogenetic species, he wrote me back and told me that this is impossible! I sent him some animals to check and he wrote me back that this was Procambarus clarkii. ;-) Also he told me that I need to look better because there have to be males and I should learn the difference between males and females.

In 2002, I had my first articles in some aquarium magazines describing the animal and warning already. I wrote an article and offered $3000 for a person bringing me a male Marmorkrebs... this was published in several magazines but nothing happened. Then I went to the USA myself to collect, and I was pretty sure that the Marmorkrebs was very close to Procambarus fallax. I send some animals to Berlin and they approved it. So this is the story of the Marmorkrebs from my side.

Thank you for providing that bit of history!


Lukhaup C, Pekny R. 2006. Cherax (Cherax) holthuisi, a new species of crayfish (Crustacea: Decapoda: Parastacidae) from the centre of the Vogelkop Peninsula in Irian Jaya (West New Guinea), Indonesia. Zoologische Mededelingen 80(1): 101-107. http://www.repository.naturalis.nl/document/41228

Lukhaup C, Pekny R. 2008. Cherax (Astaconephrops) boesemani, a new species of crayfish (Crustacea: Decapoda: Parastacidae) from the centre of the Vogelkop Peninsula in Irian Jaya (West New Guinea), Indonesia. Zoologische Mededelingen 82: 331-340. http://www.zoologischemededelingen.nl/82/nr02/a33

Scholtz G, Braband A, Tolley L, Reimann A, Mittmann B, Lukhaup C, Steuerwald F, Vogt G. 2003. Parthenogenesis in an outsider crayfish. Nature 421(6925): 806-806. http://dx.doi.org/10.1038/421806a

External links

Chris Lukhaup on Facebook
Chris Lukhaup’s pictures on Flickr