09 October 2018

Gatzmann and colleagues, 2018

Gatzmann F, Falckenhayn C, Gutekunst J, Hanna K, Raddatz G, Carneiro VC, Lyko FJE. 2018. The methylome of the marbled crayfish links gene body methylation to stable expression of poorly accessible genes. Epigenetics & Chromatin 11(1): 57. https://doi.org/10.1186/s13072-018-0229-6

Abstract

Background: The parthenogenetic marbled crayfish (Procambarus virginalis) is a novel species that has rapidly invaded and colonized various different habitats. Adaptation to different environments appears to be independent of the selection of genetic variants, but epigenetic programming of the marbled crayfish genome remains to be understood.

Results: Here, we provide a comprehensive analysis of DNA methylation in marbled crayfish. Whole-genome bisulfite sequencing of multiple replicates and different tissues revealed a methylation pattern that is characterized by gene body methylation of housekeeping genes. Interestingly, this pattern was largely tissue invariant, suggesting a function that is unrelated to cell fate specification. Indeed, integrative analysis of DNA methylation, chromatin accessibility and mRNA expression patterns revealed that gene body methylation correlated with limited chromatin accessibility and stable gene expression, while low-methylated genes often resided in chromatin with higher accessibility and showed increased expression variation. Interestingly, marbled crayfish also showed reduced gene body methylation and higher gene expression variability when compared with their noninvasive mother species, Procambarus fallax.

Conclusions Our results provide novel insights into invertebrate gene body methylation and its potential role in adaptive gene regulation.

Keywords: None provided.

05 October 2018

Anastácio and colleagues, 2019

Anastácio PM, Ribeiro F, Capinha C, Banha F, Gama M, Filipe AF, Rebelo R, Sousa R. 2019. Non-native freshwater fauna in Portugal: A review. Science of The Total Environment 650: 1923-1934. https://doi.org/10.1016/j.scitotenv.2018.09.251

Abstract

We present the most updated list of non-native freshwater fauna established in Portugal, including the Azores and Madeira archipelagos. This list includes 67 species at national level but corresponds to 84 species records, of which 53 are in the mainland, 23 in the Azores and 8 in Madeira archipelagos. We also discuss the progression of the cumulative number of introductions since 1800 and identify the most probable vectors of introduction, main taxonomic groups and their regions of origin. Furthermore, we review the existing knowledge about ecological and economic impacts, invasion risk and potential distribution of invaders, under present and future climatic conditions, and the applied management actions, including the production of legislation. Along the 20th century the number of successful introductions increased at an approximate rate of two new species per decade until the beginning of 1970s. Since then, this rate increased to about 14 new species per decade. These introductions were mainly a result of fisheries, as contaminants or for ornamental purposes. Fish and mollusks are the taxonomic groups with more established species, representing more than half of the total. Most species (>70%) are native from other regions of Europe and North America. Studies about ecological or socioeconomic impacts are more common for fish, crustaceans and mollusks. Impacts for most amphibians, reptiles and mammals are not thoroughly studied. A few studies on the impacts and management actions of health-threatening mosquitoes are also available. The potential distribution in the Portuguese territory was modelled for 26 species. Only a minority of these models provides projections of distributions under scenarios of future climate change. A comparison of the Portuguese and EU legislation shows large discrepancies in the invasive species lists. Using the EU list and a ranking procedure for the national context, we identify freshwater species of high national concern for which actions are urgently needed.

Keywords: invasions • exotic species • Iberian Peninsula • risk assessment • inland waters • aquatic systems

25 September 2018

Göpel and Wirkner, 2018

Göpel T, Wirkner CS. 2018. Morphological description, character conceptualization and the reconstruction of ancestral states exemplified by the evolution of arthropod hearts. PLOS ONE 13(9): e0201702. https://doi.org/10.1371/journal.pone.0201702

Abstract

Arthropods are the most species-rich taxon within Metazoa and have gone through major evolutionary changes with regard to body organization. Arthropod hearts and their associated vascular systems are thus morphologically highly disparate: while some arthropods exhibit very powerful hearts and complex vascular systems, other arthropods do not possess any kind of vascular system or heart at all. A comprehensive study investigating the structure of arthropods hearts has never been undertaken. In this study, we therefore investigate the hearts of 34 species from all major arthropod groups using various imaging techniques (confocal laser scanning microscopy, micro-computed tomography, histology) and describe them by addressing different aspects of heart morphology, e.g. the structure of the myocard or the composition of ostia. In a next step, we conceptualize 18 characters related to heart morphology and their respective character states and–using additional data from the literature–score a matrix for a total of 45 species from 38 supraspecific taxa. We map the characters onto prevailing phylogenetic hypotheses and perform parsimony-based ancestral state reconstruction to trace the evolutionary transformations undergone by arthropod hearts. An exploration of the character concepts (as explanatory hypotheses) reveals ontological peculiarities of character statements that clearly distinguish them in terms of ontological status from descriptive statements (i.e. descriptions of morphemes). The implications of these findings influence the interpretation of ground patterns as explanations. This first phylogenetic approach to heart morphology in the arthropod ground pattern reveals numerous new putative synapomorphies and leads to a reconsideration of the morphology of circulatory systems in early arthropods. Hypotheses on the evolution of hearts in (Pan-) Arthropoda are illustrated and discussed.

Keywords: None provided.

24 September 2018

Crayfish crimes 2

I mentioned a couple of weeks back that an American man had been convicted for selling and exporting crayfish as pets. Another case came to attention recently. An Australian man was convicted and fined AUD$8,550 for catching the world’s largest freshwater invertebrate, Astacopsis gouldii. The crayfish is threatened and protected by law.

I mention this because protecting invertebrates is hard, and law enforcement on this sort of issue is rare. It’s encouraging to see.

Related posts

Crayfish crimes

External links

Largest ever fine for poaching giant freshwater crayfish

21 September 2018

Linzmaier and colleagues, 2018

Linzmaier SM, Goebel LS, Ruland F, Jeschke JM. 2018. Behavioral differences in an over-invasion scenario: marbled vs. spiny-cheek crayfish. Ecosphere 9(9): e02385. https://doi.org/10.1002/ecs2.2385

Abstract

New species often invade ecosystems already dominated by previous invaders. Ornamental freshwater crayfish, particularly parthenogenetic marbled crayfish (Procambarus virginalis), increasingly establish in European water bodies where they interact with resident native and non-native species. Behavioral traits and behavioral syndromes can influence the outcome of these species interactions. The behavior of non-native crayfish is often studied in notorious invaders but rarely in new and emerging species, although those provide the best opportunity for management. Activity, aggressiveness, and boldness have repeatedly been associated with invasion success and species displacement. Further, crayfish can adapt their behavior after they have established in the new range. We investigated whether marbled crayfish can displace the widely established spiny-cheek crayfish (Orconectes limosus). Specifically, we compared their behavioral traits and evaluated whether these traits differ, using marbled crayfish populations from aquaria and the field and spiny-cheek crayfish from the field.We staged agonistic encounters, measured activity levels, and recorded the response to a simulated threat of both species and both origins (field and aquarium) in laboratory trials. We found that in agonistic encounters, marbled crayfish were on average more aggressive than spiny-cheek crayfish, even against larger opponents. Aggressiveness and activity were positively correlated, which is indicative for an aggression syndrome. Marbled crayfish from the field were less active than those from aquaria, but there was no difference in aggressiveness. Marbled crayfish often froze in response to a simulated threat, whereas spiny-cheek crayfish reacted either offensively or defensively. These results from the laboratory illustrate potentially important behavioral mechanisms behind crayfish over-invasions and show behavioral plasticity in a species where all known individuals are genetically identical. To better understand the invasion process in nature, the species’ reproductive biology and interactions with other members of the community should be considered. We conclude that the recent success of marbled crayfish in establishing new populations could be influenced by their behavioral flexibility and their potential to competitively persist in the presence of established invasive crayfish.

Keywords: aggression • behavioral flexibility • behavioral syndromes • behavioral variability • biological invasions • freshwater crayfish • shelter use • threat response

19 September 2018

The Maltese crayfish: A dozen invaded European countries


It was Germany, then Italy, then the Netherlands, then Hungary, then Croatia, then Slovakia, then Romania, then Sweden, then the Ukraine, then the Czech Republic, then Estonia, and now Malta.

Malta makes it an even dozen European countries where Marmorkrebs have been found in outdoors, according to a paper in press from Deidun and colleagues. This is not a few stray individuals, either. Some sites (visited in 2016 and 2017) had hundreds of individuals. I will add the paper to the collection of abstract on the blog once the final paginated version is published.

I have updated the map of Marmorkrebs introductions accordingly.

My only consolation is that at some point, I’m going to run out of European countries to add to the list. Marmorkrebs will be in all of them.



Reference

Deidun A, Sciberras A, Formosa J, Zava B, Insacco G, Corsini-Foka M, Crandall KA. Invasion by non-indigenous freshwater decapods of Malta and Sicily, central Mediterranean Sea. Journal of Crustacean Biology: in press. http://dx.doi.org/10.1093/jcbiol/ruy076

External links

Alien crayfish invade Malta’s valleys and watercourses
Alien crayfish have invaded Malta’s valleys, study finds

13 September 2018

Cover cray


Nice cover accompanying this blog post. It’s covering the Marmorkrebs genome paper that came out back in February, but better late than never! The photo is aces in any case.

External links

Decoding the mutant, all-female, self-cloning crayfish

Crayfish crimes

Prosecutions for anything to do with the aquarium trade is rare, but last week, news reported Justin Doyle Pierce, an American was prosecuted for selling crayfish as pets, in violation of the Lacey Act)

Pierce sold over $19,000 worth of crayfish illegally, and for this, he got a $500 fine, 20 hours of community service, and a year on probation. By my quick scan of the act, he could have received jail time and thousands of dollars in fines.

Is this sort of enforcement acting as a deterrent? It’s not clear. When someone can make that much money, the fine is little more than a clap on the wrist. The real penalty may not be the fine or the service, but the criminal record. Pierce wrote:

(T)his will result in my disqualification of future employment in areas related to wildlife and conservation.

External links

Feds pinch Camden County man for illegal crayfish sales
Overview of the Lacey Act (16 U.S.C. SS 3371-3378)
Lacey Act cases

Hossain and colleagues, 2018

Hossain MS, Patoka J, Kouba A, Buřič M. 2018. Clonal crayfish as biological model: a review on marbled crayfish. Biologia 73(9): 841-855. https://doi.org/10.2478/s11756-018-0098-2

Abstract

Since the mid-twentieth century, numerous vertebrates and invertebrates have been used as model organisms and become indispensable tools for exploring a broad range of biological and ecological processes. Crayfish seem to be adequate models which resulted in their involvement in research. In the two decades since its discovery, ongoing research has confirmed that the marbled crayfish (Procambarus virginalis Lyko, 2017) is an ideal taxon in this regard, especially due to its almost continuous asexual reproduction providing a source of genetically identical offspring. This review provides an overview of the occurrence, biology, ecology, ethology, and human exploitation of marbled crayfish with primary focus on its use as a laboratory model organism as well as potential risks to native biota in case of its introduction. Genetic uniformity, ease of culture, and a broad behaviour repertoire fosters the use of marbled crayfish in epigenetics and developmental biology, as well as physiological, ecotoxicological, and ethological research. Marbled crayfish could be further exploited for basic and applied fields of science such as evolutionary biology and clonal tumour evolution. However, due to its high invasive potential in freshwater environments security measures must be taken to prevent its escape into the wild.

Keywords: model species • epigenetics • developmental biology • Procambarus virginalis • biological invasion

01 September 2018

Naboka and colleagues, 2018

Naboka A, Marenkov O, Kovalchuk J, Shapovalenko Z, Nesterenko O, Dzhobolda B. 2018. Parameters of the histological adaptation of Marmorkrebs Procambarus virginalis (Lyko, 2017) (Decapoda, Cambaridae) to manganese, nickel and lead ions pollution. International Letters of Natural Sciences 70: 24-33. https://doi.org/10.18052/www.scipress.com/ILNS.70.24

Abstract

Manganese, lead and nickel are heavy metals, which are the primary fresh water toxic contaminants being in the most dangerous class of chemicals. Heavy metals cause functional disorders in the tissues and organs of hydrobionts, affecting their linear and weight indices, reproductive system, digestive and extraction organs. In our experiment on marbled crayfish Procambarus virginalis (Lyko, 2017) we studied the long-term effects of various concentrations of heavy metal ions on the physiological state and histostructure of tissues and organs. According to the results of research, it was found that among the studied heavy metals nickel ions influenced the weight indexes and mortality of crustaceans the most negatively. The results of morphometric studies on marbled crayfish indicate no significant differences between the control group and experimental one, but heavy metals influenced the form of the hepatopancerase lobes and the size of the lumen of the gland. Research on adipocytes of the connective tissue showed a significant difference between the size of cells under the influence of heavy metals. Dimensions of adipocytes fluctuated over a wide range from 144 μm2 to 537 μm2. In control group the adipocyte area was 406.96 μm2. Experimental studies of hemolymph showed that, under the influence of lead ions, a significant 1.4 times increase was observed in the area of hemolymph cells; when manganese and nickel were added, moderate decrease was observed in cells. It was found that under the influence of nickel, the area of round hyalinocytes has reduced by 1.7 times.

Keywords: Procambarus virginalis • glandulocytes • hepatopancreas • hemolymph • manganese • nickel • lead • crustaceans

16 August 2018

Soes, 2016

Soes DM. 2016. Onderzoek voorkomen marmerkreeft in Middelburg. Rapportnummer 16‐250. Bureau Waardenburg, Culemborg. https://doi.org/10.13140/RG.2.2.10943.82081

Abstract

De marmerkreeft is een in Nederland exotische rivierkreeft die valt onder de recent inwerking getreden Europese exotenverordening (EU 1143/2014). Van de marmerkreeft zijn uit Nederland tot op heden geen populaties bekend (Koese & Soes, 2011; D.M. Soes eigen informatie). Voor de marmerkreeft is het dan ook van belang nieuwe vestigingen snel te signaleren zodat eventueel maatregelen kunnen worden genomen die verdere verspreiding tegengaan of zelfs eliminatie mogelijk maken.

In 2014 en 2015 zijn in het westen van Middelburg (omgeving Hugo de Grootlaan) twee vondsten van mogelijke marmerkreeften gedaan. Eén waarneming betrof een dood exemplaar in een brandgang. Het tweede exemplaar werd levend aangetroffen in een tuinvijver. Verder is er nog een ongedateerde waarneming van een levende kreeft in dezelfde brandgang. Deze informatie was voor de NVWA aanleiding nader onderzoek uit te voeren.

In onderhavig rapportage wordt beschreven:
  1. de definitieve determinatie van de gevonden kreeften;
  2. een inventarisatie naar het eventueel voorkomen van de soort in de directe omgeving van de genoemde vondsten;
  3. de kansen op verspreiding indien zij in het westen van Middelburg daadwerkelijk zou voorkomen.
Keywords: None provided.

(English translation with Google Translate and some guesswork)

The marbled crayfish is a exotic crayfish in the Netherlands that falls under the recent the European Exotics Regulation (EU 1143/2014) came into effect. There are no populations known to date from the Netherlands (Koese & Soes, 2011; D.M. Soes, unpublished). It is therefore important for the early detection of marbled crayfish in new river branches quickly so that possible measures can be taken to prevent further dissemination or even enable elimination.

In 2014 and 2015 in the west of Middelburg (near Hugo de Grootlaan), two possible marbled crayfish were found. One observation was one dead individual in a firebreak. The second individual was found alive in a garden pond. There is also an undated observation of a living crayfish in the same firebreak. This information was further explained by the NVWA conduct research.

This report describes:
1. the definitive determination of the crayfish found;
2. an inventory of the possible occurrence of the species in the direct environment of the findings;
3. the chances of spreading if they are in the west of Middelburg.

14 August 2018

Marenkov and colleagues, 2018

Marenkov O, Prychepa M, Kovalchuk J. 2018. The influence of heavy metal ions on the viability and metabolic enzyme activity of the marbled crayfish Procambarus virginalis (Lyko, 2017). International Letters of Natural Sciences 70: 11-23. https://doi.org/10.18052/www.scipress.com/ILNS.70.11

Abstract

The article shows the results of studies on the influence of heavy metal ions (manganese, nickel, lead) on the viability and metabolic enzyme activity of marbled crayfish Procambarus virginalis (Lyko, 2017) (Decapoda). Due to the fact that marbled crayfish got into the reservoirs of the Dnipropetrovsk region in 2015, it was necessary to study the possibilities of its adaptation to environmental factors of reservoirs for further prediction of its distribution or even acclimatization under conditions of toxicological contamination of the ponds of the steppe Prydniprovya. In the
experiment with marbled crayfish, chronic effects of various concentrations of heavy metal ions on the physiological state and enzyme activity were investigated. The obtained results showed that
among the investigated heavy metals nickel ions influenced the weight indexes and mortality of crustaceans the most negatively. According to the results of the research, significant changes were
noted in the individual biochemical parameters of marbled crayfish under the influence of manganese, lead and nickel ions. The most significant changes in the activity of lactate dehydrogenase were detected in muscle tissues affected by manganese and nickel ions. A significant decrease in the activity of succinate dehydrogenase in muscle of marbled crayfish was determined after the action of heavy metal ions. Investigation of changes in the activity of alkaline phosphatase under the influence of the ions of manganese, lead and nickel has its own characteristics, which indicates certain violations in the tissues of cell membranes. Changes in the activity of enzymes were also reflected in the overall protein content. In conclusion, changes in these parameters may indicate a rapid biochemical response of crustaceans to the toxic effects of heavy metals.

Keywords: manganese • nickel • lead • crustaceans • Procambarus virginalis • succinate • dehydrogenase • lactate dehydrogenase • alkaline phosphatase

04 August 2018

“Say my name, say my name”: The Guardian podcast

Marmorkrebs make an appearance in the Guardian's Science Weekly podcast as part of a discussion about naming species. If you're super directed, the marbled crayfish discussion with Tim Cockerill starts about 7 minutes in (07:20, to be exact).

This podcast raises a question for me, though. What is the preferred pronunciation of “slough”? As in Procambarus fallax, the slough crayfish? The podcast presenter, Graihagh Jackson, has it rhyme with “cow.” I’ve always pronounced with to rhyme with “you.” As this post notes, words ending in "-ough" have a bewildering number of sounds.

External links

Tricky taxonomy: the problems with naming new species

31 July 2018

The Great Lakes least wanted

The Michigan Sea Grant has spearheaded a “#CrayWeek” campaign for the second year in a row! Of course I’m participating.

One of the piece of information that Michigan Sea Grant tweeted out was that Marmorkrebs have found themselves on another invasive species watch list, this one for the Canadian / American Great Lakes and Saint Lawrence River.

On May 4, 2018, the Great Lakes St. Lawrence Governors & Premiers announced five additions to the list of “least wanted” aquatic invasive species. In 2013, the Governors and Premiers released the first list of 16 “least wanted” aquatic invasive species (AIS) that present a serious threat to the Great Lakes St. Lawrence Basin. Since then, the region’s eight states and two provinces have taken more than 40 actions to prohibit or restrict these high-risk species, including the Asian carp. The new “least wanted” AIS include:
  • Tench Tinca tinca
  • Marmorkreb (sic) (marbled crayfish) Procambarus fallax forma virginalis
  • New Zealand mud snail Potamopyrgus antipodarum
  • European frogbit Hydrocharis morsus-ranae
  • Yellow floating heart Nymphoides peltata
State and provincial AIS and fisheries experts, in conjunction with leading regional researchers, identified these five AIS as posing a high risk of invasion or spread within the region. The Governors and Premiers will take aggressive action and work with regional partners to prevent the spread of these aquatic invaders.

What’s not clear to me from this statment is what action has been, or might be, taken to try to curb the spread of any of these species. A recent paper I co-authored pointed out (Patoka et al. 2018), the track record of legislation on curbing the movement of aquarium pets is... not great.

External links

Great Lakes St. Lawrence Governors & Premiers Add Five “Least Wanted” AIS

References

Patoka J, Magalhães ALB, Kouba A, Faulkes Z, Jerikho R, Vitule JRS. 2018. Invasive aquatic pets: Failed policies increase risks of harmful invasions. Biodiversity and Conservation 27(11): 3037-3046. https://doi.org/10.1007/s10531-018-1581-3

26 July 2018

Le Page, 2018

Le Page M. 2018. Crayfish clone army on the loose. New Scientist 239(3185): 16. https://doi.org/10.1016/S0262-4079(18)31193-X

Abstract

Without abstract. First paragraph:

Sometime before 1995, a container of freshwater crayfish from Florida got too hot or too cold en route to a pet shop in Germany. The shock disrupted the development of an egg being carried by one of the females, creating an army of clones that are invading rivers and lakes in continental Europe, Madagascar and Japan.

Keywords: None provided.

Notes: If you click to enlarge the cover of this issue, the cover includes “Clone crayfish” in the bottom left. This article was published online with the title, “Freak accident created a massive army of super-fertile clones.”

14 July 2018

Nischik and Krieger, 2018

Nischik ES, Krieger J. 2018. Evaluation of standard imaging techniques and volumetric preservation of nervous tissue in genetically identical offspring of the crayfish Procambarus fallax cf. virginalis (Marmorkrebs). PeerJ 6: e5181. https://doi.org/10.7717/peerj.5181

Abstract

In the field of comparative neuroanatomy, a meaningful interspecific comparison demands quantitative data referring to method-specific artifacts. For evaluating the potential of state-of-the-art imaging techniques in arthropod neuroanatomy, micro-computed X-ray microscopy (μCT) and two different approaches using confocal laser-scanning microscopy (cLSM) were applied to obtain volumetric data of the brain and selected neuropils in Procambarus fallax forma virginalis (Crustacea, Malacostraca, Decapoda). The marbled crayfish P. fallax cf. virginalis features a parthogenetic reproduction generating genetically identical offspring from unfertilized eggs. Therefore, the studied organism provides ideal conditions for the comparative analysis of neuroanatomical imaging techniques and the effect of preceding sample preparations of nervous tissue. We found that wet scanning of whole animals conducted with μCT turned out to be the least disruptive method. However, in an additional experiment it was discovered that fixation in Bouin’s solution, required for μCT scans, resulted in an average tissue shrinkage of 24% compared to freshly dissected and unfixed brains. The complete sample preparation using fixation in half-strength Karnovsky’s solution of dissected brains led to an additional volume decrease of 12.5%, whereas the preparation using zinc-formaldehyde as fixative resulted in a shrinkage of 5% in comparison to the volumes obtained by μCT. By minimizing individual variability, at least for aquatic arthropods, this pioneer study aims for the inference of method-based conversion factors in the future, providing a valuable tool for reducing quantitative neuroanatomical data already published to a common denominator. However, volumetric deviations could be shown for all experimental protocols due to methodological noise and/or phenotypic plasticity among genetically identical individuals. MicroCT using undried tissue is an appropriate non-disruptive technique for allometry of arthropod brains since spatial organ relationships are conserved and tissue shrinkage is minimized. Collecting tissue-based shrinkage factors according to specific sample preparations might allow a better comparability of volumetric data from the literature, even if another technique was applied.

Keywords: μCT • confocal laser scanning microscopy • nervous system • volumetry • Marmorkrebs • phenotypic plasticity

10 July 2018

Conference hashtag #IAA22

I was unable to go to the International Association of Astacology meeting this year, but have been following along on Twitter, using the #IAA22 hashtag. Those following from home have been fortunate to have Maggie Watson sketchnoting many of the presentations, and I can’t resist sharing her Marmorkrebs notes here and here)!


If you go to a conference, tweet about it. More people want to attend than can attend.

07 July 2018

Velisek and colleagues, 2018

Velisek J, Stara A, Zuskova E, Kubec J, Buric M, Kouba A. 2018. Chronic toxicity of metolachlor OA on growth, ontogenetic development, antioxidant biomarkers and histopathology of early life stages of marbled crayfish. Science of The Total Environment 643: 1456-1463. https://doi.org/10.1016/j.scitotenv.2018.06.309

Abstract

The metolachlor OA is a metabolite of herbicide metolachlor and s-metolachlor. The objective of the present study was to assess the effect metolachlor OA on early life stages of marbled crayfish (Procambarus virginalis). The early life stages of marbled crayfish were exposed for 45 days to three concentrations of metolachlor OA: 4.2 μg/L (environmentally relevant concentration, E1), 42 μg/L (E2) and 420 μg/L (E3) under laboratory conditions. The effects were assessed on the basis of mortality, growth, ontogenetic development, behaviour, oxidative stress, antioxidant biomarkers and histopathology. Metolachlor OA caused significantly lower growth, superoxide dismutase, catalase and glutathione s-transferase activity in all tested concentrations. Metolachlor OA in higher concentrations (42 and 420 μg/L) resulted in significantly delayed ontogenetic development, lower reduced glutathione level and lipid peroxidation. Metolachlor OA has not significant effect on behaviour (activity, total distance moved and walking speed). Histological examination revealed alteration of hepatopancreas and gills in crayfish exposed to two higher tested concentrations. Hepatopancreas reflected histomorphological structural changes of individual cell types. Changes of gills included focal hemocytic infiltration together with enlargement of intralamellar space packed with granular substance. In conclusion, chronic metolachlor OA exposure affected growth, ontogenetic development, and the antioxidant system and caused pathological changes in hepatopancreas and gills of early life stages of marbled crayfish.

Keywords: herbicide • metabolite • crayfish • mortality • behaviour • oxidative stress

03 July 2018

Vogt and colleagues, 2018

Vogt G, Dorn NJ, Pfeiffer M, Lukhaup C, Williams BW, Schulz R, Schrimpf A. 2018. In-depth investigation of the species problem and taxonomic status of marbled crayfish, the first asexual decapod crustacean. BioRxiv: 26 June 2018. https://doi.org/10.1101/356170 [Unreviewed pre-print]

Abstract

The marbled crayfish is the only obligately parthenogenetic decapod crustacean and a novel research model and invasive animal on three continents. It is regarded either as a parthenogenetic form of slough crayfish Procambarus fallax or as a separate species named Procambarus virginalis. In order to investigate the species question of this unusual crayfish in detail we have identified the similarities and differences in morphology, life history, genetics, behaviour, ecology and biogeography between marbled crayfish and P. fallax. We have investigated specimens from natural habitats, laboratory colonies and museum collections and performed a meta-analysis of our data and published data. Our COI based molecular tree with 27 Cambaridae confirms closest relationship of marbled crayfish with P. fallax. Marbled crayfish and P. fallax are similar with respect to morphological characters, coloration and body proportions, but differ considerably with respect to body size, fertility and longevity. The mitochondrial genes of both crayfish are similar, but some nuclear genomic features are markedly different. Both crayfish are eurytopic and have two major annual recruitment periods, but marbled crayfish show different population structure and higher invasiveness. Marbled crayfish occur in boreal to tropical habitats of Europe, Madagascar and Japan, but P. fallax is confined to the subtropics and tropics of the southeastern USA. Laboratory experiments suggest reproductive isolation of both crayfish. The application of the Evolutionary Genetic Species Concept for asexuals to all available data supports raising marbled crayfish from "forma" to species rank. A determination key is provided to discriminate Procambarus virginalis, the first asexual decapod species, from its most likely parent species P. fallax.

Keywords: None provided.



22 June 2018

Vogt, 2018c

Vogt G. 2018. Glair glands and spawning in unmated crayfish: a comparison between gonochoristic slough crayfish and parthenogenetic marbled crayfish. Invertebrate Zoology 15(2): 215–220. https://doi.org/10.15298/invertzool.15.2.02, http://kmkjournals.com/journals/Inv_Zool/IZ_Index_Volumes/IZ_15/IZ_15_2_215_220_Vogt

Abstract

In the period before spawning, freshwater crayfish females develop glair glands on the underside of the pleon. These glands produce the mucus for a gelatinous tentlike structure in which the eggs are fertilized and attached to the pleopods. Long-term observation of females of the sexually reproducing slough crayfish, Procambarus fallax, kept in captivity revealed that the glair glands developed in late winter and late summer of each year independently of the presence of males. In mated females, they secreted their contents shortly before spawning. In contrast, unmated females of slough crayfish did
neither empty their glair glands nor spawn. Their glands persisted for an unusually long period of time and disappeared only during the next moult. Apparently, slough crayfish females use information on sperm availability to either spawn or save the resources. Females of marbled crayfish, Procambarus virginalis, a parthenogenetic all-female descendant of slough crayfish, developed glair glands in approximately the same periods of the year but generally spawned despite of the lack of males. These findings suggest that in marbled crayfish glair secretion and spawning is decoupled from mating. Therefore, the species pair P. fallax and P. virginalis seems to be particularly suitable to investigate the regulation of spawning in freshwater crayfish.

Keywords: freshwater crayfish • glair gland • spawning • mating • Procambarus fallaxProcambarus virginalis


Zoo babies


Marbled crayfish are featured in this year’s Cincinnati Zoo’s Zoo Babies display! The Zoo’s website shows they are part of the display, but no more. I do complement their photographer for the particularly cute crayfish pic (above) on their site.

I reached out to the Zoo, and heard back from Mandy Pritchard, who is the “World of the Insect Team Leader” at the zoo. (Now there’s a great job title.) She was kind enough to send me a couple of pictures of the display:




There’s a very nice shirt available. Unfortunately, it’s doesn’t seem to be available in adult sizes.


Based on the description in the display, I think these are the sexual slough crayfish and not Marmorkrebs. But it’s fun to see crayfish on display nevertheless!

External links

Zoo Babies
The "Amazing" Marbled Crayfish - Youth Garments

19 June 2018

Herrmann and colleagues, 2018

Herrmann A, Schnabler A, Martens A. 2018. Phenology of overland dispersal in the invasive crayfish Faxonius immunis (Hagen) at the Upper Rhine River area. Knowledge and Management of Aquatic Ecosystems 419: 30. https://doi.org/10.1051/kmae/2018018

Abstract

The non-indigenous crayfish Faxonius immunis (Hagen) is the dominant crayfish species at the Upper Rhine River system since his detection in 1993. As an invasive alien species, it is one of the biggest threats to aquatic biodiversity in the area. By dispersing over land, the species has a high potential to colonize small ponds created for threatened amphibians and dragonflies. Shortly after invasion, the fast growing population of F. immunis is changing the habitat drastically. In June 2016, our team started a local information campaign including citizen science project where the local people south of Karlsruhe, Baden-Wuerttemberg, Germany, could contact us when they spot a crayfish migrating over land to assess the activity of overland dispersal on a regional scale. Until January 2018, we got a total of 98 responses. Thirty-nine include suitable information including 33 records of overland dispersal of F. immunis. The species was recorded on land throughout the year, except February and July. Additionally, single observations of overland dispersal of other invasive crayfish species, naming Procambarus clarkii (Girard), Pacifastacus leniusculus (Dana), Procambarus virginalis (Lyko) and Faxonius limosus (Rafinesque), were recorded.

Keywords: amphibian conservation • citizen science • management • biological invasions • non-indigenous species

08 June 2018

If this is 2018, this must be Estonia

Estonia has now become the...

Wait a second, I’ve lost count.

  1. Germany.
  2. Italy.
  3. Netherlands.
  4. Hungary.
  5. Croatia.
  6. Slovakia.
  7. Romania.
  8. Sweden.
  9. Ukraine.
  10. Czech Republic.
  11. ...
Eleventh European country where Marmorkrebs have been found in outdoors. This is according to a press release from the Estonian Research Council. The crayfish were collected last year, not recognized as Marmorkrebs until the end of the year, and a repeat visit at the end of May confirmed a population was there.

I have updated the map of Marmorkrebs introductions accordingly.

External links

The marbled crayfish have established themselves in Narva power plant

30 May 2018

Scholz and colleagues, 2018

Scholz S, Richter S, Wirkner CS. 2018. Constant morphological patterns in the hemolymph vascular system of crayfish (Crustacea, Decapoda). Arthropod Structure & Development 47(3): 248-267. https://doi.org/10.1016/j.asd.2017.12.005

Abstract

We present a study of the hemolymph vascular system of the marbled crayfish, Procambarus fallax f. virginalis, the only crayfish species known to be parthenogenetic. To identify potential evolutionary patterns, we compared data from a total of 48 specimens of P. fallax with 22 specimens of Orconectes limosus. Visualizations (2D and 3D) were carried out using a combination of classical and modern morphological techniques. Our data were compared to the existing literature. Like all Decapoda, both P. fallax and O. limosus have a hemolymph vascular system, consisting of a globular heart with seven off-branching arteries. We were able to visualize in detail the heart of crayfish for the first time, i.e., the heart muscle itself, with its loose bundles of myofibrils, as well as the valves and flaps of ostia and arteries. Furthermore, the branching patterns of the seven artery systems were analyzed. Anatomical structures identified to be consistent in all specimen of both species were combined, and a proposed schematic anatomy established of the hemolymph vascular system of crayfish.

Keywords: artery • circulatory system • evolutionary morphology • heart

Nentwig and colleagues, 2018

Nentwig W, Bacher S, Kumschick S, Pyšek P, Vilà M. 2018. More than “100 worst” alien species in Europe. Biological Invasions 20(6): 1611–1621. https://doi.org/10.1007/s10530-017-1651-6

Abstract

“One hundred worst” lists of alien species of the greatest concern proved useful for raising awareness of the risks and impacts of biological invasions amongst the general public, politicians and stakeholders. All lists so far have been based on expert opinion and primarily aimed at representativeness of the taxonomic and habitat diversity rather than at quantifying the harm the alien species cause. We used the generic impact scoring system (GISS) to rank 486 alien species established in Europe from a wide range of taxonomic groups to identify those with the highest environmental and socioeconomic impact. GISS assigns 12 categories of impact, each quantified on a scale from 0 (no impact detectable) to 5 (the highest impact possible). We ranked species by their total sum of scores and by the number of the highest impact scores. We also compared the listing based on GISS with other expert-based lists of the “worst” invaders. We propose a list of 149 alien species, comprising 54 plants, 49 invertebrates, 40 vertebrates and 6 fungi. Among the highest ranking species are one bird (Branta canadensis), four mammals (Rattus norvegicus, Ondatra zibethicus, Cervus nippon, Muntiacus reevesi), one crayfish (Procambarus clarkii), one mite (Varroa destructor), and four plants (Acacia dealbata, Lantana camara, Pueraria lobata, Eichhornia crassipes). In contrast to other existing expert-based “worst” lists, the GISS-based list given here highlights some alien species with high impacts that are not represented on any other list. The GISS provides an objective and transparent method to aid prioritization of alien species for management according to their impacts, applicable across taxa and habitats. Our ranking can also be used for justifying inclusion on lists such as the alien species of Union concern of the European Commission, and to fulfil Aichi target 9.

Keywords: Aichi target 9 • environmental impacts • generic impact scoring system (GISS) • prioritization of alien species • risk assessment • socio-economic impacts

23 May 2018

Rymut, 2018


Rymut, JA. 2018.Determining the effects of nitric oxide on Procambarus fallax forma virginalis. Poster given at the International Crustacean Congress IX, Washington DC, USA, 22-25 May 2018. http://www.birenheide.com/ICC2018/program/singlesession.php3?sessid=P, poster P.33.

Abstract

Ethanol (EtOH) effects inducible nitric oxide synthase (iNOS) activity by inhibiting the production of iNOS in cells. Acute doses increase the production of nitric oxide (NO) and endothelial NOS (eNOS). At higher dosages, ethanol impairs endothelial functions. NO has been found to suppress the feeding response in pond snails, Lymnaea stagnalis, induce synaptic depression in crayfish, and inhibit the swimming rhythm of Xeonpus laevis tadpoles. This in vivo study will be performed in order to determine if synaptic depression is caused by free radical NO and determine if overall movements are decreased in Procambarus forma fallax virginalis (P.f.f virginalis) in the presence of NO. It was hypothesized that there will be a depression in synaptic activity and less movement in crayfish exposed to free radical NO. A probe will be inserted near the cerebral ganglion to assess depression in synaptic inputs. Movement will be tested by placing crayfish into a partitioned tank and counting each movement across a partition as one movement. Movement will be tested on both an individual and group level to determine if group activity will be a variable factor. NO will be introduced through the usage of ethanol, an L-arginine supplement, and chlorhexidine​ in an approximate range of five to ten​ parts per million (​5 ​mg/L​ and 10 mg/L​).

Keywords: None provided.


Update, 30 May 2018: At the author’s request, here is the updated abstract from the poster as it was presented at the meeting (above).

Ethanol (Et-OH) effects inducible nitric oxide synthase (iNOS) activity by inhibiting the production of iNOS in cells. Acute doses increase the production of nitric oxide (NO) and endothelial NOS (eNOS). At higher dosages, ethanol impairs endothelial functions. NO has been found to suppress the feeding response in pond snails, Lymnaea stagnalis, induce synaptic depression in crayfish, and inhibit the swimming rhythm of Xenopus laevis tadpoles (Aonuma, et al. 2000). This in vivo study has been performed in order to determine if synaptic depression is caused by NO, and if overall movements are decreased in Procambarus forma fallax virginalis (P.f.f virginalis) and Procambarus blandingii, in the presence of NO. Movement was assessed in a labeled gridded tanks of water, denatured ethanol (3 ppm), L-arginine (Reagent grade, 1ppb) and chlorhexidine (99.95%, 1ppb). There was an evident trend over a time interval of 6 minutes ≤ t ≤ 8 minutes, where the control, ethanol and chlorhexidine all had a stark drop off in activity, whilst L-arginine had a stark increase. It is hypothesized that this could be due to a metabolic pathway of L-arginine is converted through nitric oxide synthase (NOS) to L-citrulline (Racke, et al. 2010); whereas ethanol has proven to inhibit iNOS, and due to the cytostatic characteristics of chlorhexidine, it can be assumed that the correlation of chlorhexidine to ethanol lies in this pathway as well. Synaptic depression is shown where L-arginine is present, over a time interval of 0 ms ≤ t ≤ 10ms (Aonuma et al. 2010); as found in the study, there is a correlation between L-arginine and chlorhexidine pre-wash, and it is hypothesized that this is from the terminal guanylyl group.

16 May 2018

Faulkes and colleagues, 2018


Faulkes Z, DeLeon H, Thomas J. 2018. Cloning crayfish cell culture. Poster presentation given at the International Crustacean Congress IX, 22-25 May 2018, Washington, DC, USA. http://www.birenheide.com/ICC2018/program/singlesession.php3?sessid=P, poster P.81.

Abstract

The parthenogenetic marbled crayfish, Marmorkrebs, is an emerging model organism. For example, it is the only decapod crustacean with a sequenced genome, and several labs have used Marmorkrebs as a model for embryonic development. One difficulty in studying embryonic cells is that eggs contain a large amount of yolk, which can make imaging embryonic cells difficult. We successfully isolated and cultured cells from early stage Marmorkrebs embryos, and confirmed their identity using DNA sequencing. Cellular and molecular tools for use in crayfish are underdeveloped compared to other model organisms, and cultured embryonic cells could provide a new testbed for those techniques.

Keywords: None provided.

09 May 2018

Vogt, 2018b

Vogt G. 2018. Annotated bibliography of the parthenogenetic marbled crayfish Procambarus virginalis, a new research model, potent invader and popular pet. Zootaxa 4418(4): 301-352. https://doi.org/10.11646/zootaxa.4418.4.1

Abstract

The marbled crayfish Procambarus virginalis is a new obligately parthenogenetic species that was detected in the mid-1990s in the German aquarium trade. Since then it has become a popular pet in many countries throughout the world and a valuable laboratory model for a broad range of biological disciplines. Releases have led to the establishment of wild
populations in several European countries, Madagascar and probably Japan, making marbled crayfish an interesting paradigm of evolutionarily young and ongoing bioinvasions. This article provides an annotated bibliography of the scientific and popular scientific literature on marbled crayfish from its detection until today. Each reference is assigned to a publication format and one or more biological categories. The content is shortly described and its significance for marbled crayfish research and general biology is assessed. Of the 239 references listed 140 (58.6%) deal primarily with laboratory experiments on the biology of marbled crayfish and the establishment and use of marbled crayfish as a research model, 74 (31.0%) with its biogeography, invasions and ecology and 25 (10.4%) with hobby aquarist issues and the pet trade.

Keywords: Crustacea • Decapoda • development • ecology • genetics • morphology • neurobiology • physiology • speciation • stem cell biology • toxicology

08 May 2018

Zeng and Yeo, 2018

Zeng Y, Yeo DCJ. 2018. Assessing the aggregated risk of invasive crayfish and climate change to freshwater crabs: A Southeast Asian case study. Biological Conservation 223: 58-67. https://doi.org/10.1016/j.biocon.2018.04.033

Abstract

Primary freshwater crabs represent a culturally and ecologically significant component of freshwater habitats globally that has a high percentage of threatened species. Invasive species (especially non-indigenous crayfish) and climate change are not only important standalone threats, but are also expected to compound existing threats (e.g., habitat loss/modification, pollution) and challenge the long-term survival of these decapod crustaceans. This study illustrates the importance of considering these two emerging and growing threats in conservation or management strategies by quantifying (via species distribution models) the individual and aggregated risks of these threats in Southeast Asia, a region with the highest diversity of primary freshwater crabs and a high proportion of imperiled species. Results predicted that most species of crabs (82.1%) will co-occur (and hence interact) with invasive crayfish to a moderate to high degree, and most species (69.2%) will also experience a reduction in suitable climate conditions in the future. In terms of aggregated risk, the results also predict an increased overlap between invasive crayfish and native crabs for three out of the seven species analyzed (namely Procambarus virginalis, Cherax destructor and Orconectes rusticus). Findings from this study provide a quantitatively derived rationale for the development of adaptive regulations and conservation plans in the region to minimize the risk of invasive species in a cost-effective way, thereby enabling the protection of Southeast Asia's natural heritage and its vital ecosystem services.

Keywords: alien species • Cherax • environmental niche model • non-indigenous species • Procambarus • radiative forcing target levels • species distribution model

Marenkov and colleagues, 2018

Marenkov O, Batalov K, Kriachek O. 2018. Biological and biomechanical principles of the controlling molluscs Melanoides tuberculata (Müller 1774) and Tarebia granifera (Lamarck, 1822) in reservoirs of strategic importance World Scientific News 99: 71-83. http://www.worldscientificnews.com/wp-content/uploads/2018/04/WSN-99-2018-71-83.pdf

Abstract

The article presents the results of complex laboratory investigations on the biological and biomechanical ways of control of Melanoides tuberculata (Müller 1774) and Tarebia granifera (Lamarck, 1822) molluscs in simulated conditions close to the conditions of the cooling pond of the Zaporizhia Nuclear Power Plant. It was determined that molluscs have naturalized in the Zaporizhia Nuclear Power Plant cooling pond, quickly increased their number and created a threat to hydraulic structures. Taking into account biological features of Thiaridae mollusks and technical and ecological features of Zaporizhia NPP, we carried out a series of experiments using biological control measures (the use of predatory species of hydrobionts) and mechanical means for controlling mollusks. Representatives of different taxons of the Animalia Kingdom were selected as predatory species of hydrobionts, which potentially can consume gastropods: Mollusca, Crustaceans and Fish. It has been found experimentally that the use of marbled crayfish Procambarus virginalis (Lyko, 2017), pumpkinseed Lepomis gibbosus (Linnaeus, 1758) and Botia lohachata Chaudhuri, 1912 has not given positive results in the development of measures to control the number of molluscs. Positive results were obtained in a series of experiments with predatory mollusc assassin snail Clea helena (von dem Busch, 1847), but it was noted that in the presence of more accessible feeds, assassin snail Clea helena (von dem Busch, 1847) consumes smaller quantities of Thiaridae mollusks. The most successful results we obtained in experiments with traps for molluscs. We have developed experimental constructions of traps with lower and upper inlets that act as mollusk accumulator and can be installed in the coastal zone of the reservoir and Zaporizhia NPP cooling system channels for reducing the number of reproductive individuals of Melanoides tuberculata (Müller 1774) and Tarebia granifera (Lamarck, 1822). The most effective were the traps with the lower inlet to which the mollusks could get faster. In order to attract mollusks to traps, we have conducted studies on the use of feed baits for molluscs. Most effectively, molluscs fell into traps that contained lime feed, feedstock sunflower oil and anise oil. The most effective among mollusks was the bait with the addition of anise oil. During the exposure, traps with anise bait traps accumulated 14.1% of molluscs. The conducted researches can serve as the basis for the development of biomelioration measures aimed at reducing the negative impact of accidental introduction of new species of molluscs into technical reservoirs of strategic importance.

Keywords: Clea helenaMelanoides tuberculataTarebia granifera • Zaporizhia Nuclear Power Plant • assassin snail • biological invasion • cooling pond • red-rimmed melania • thiarids


(Edit, 13 September 2018: This entry was originally posted with the authors’ given names and surnames reversed. Apologies for the confusion.)

28 April 2018

Allo or auto? Betting on Marmorkrebs origins

Picture of Bugatti car with text, 'Why not hybrid?'

In a new article in PNAS, James Mallet writes:

An extraordinary recent case is the marbled crayfish Procambarus virginalis, which seems to have originated via a hybrid between two North American Procambarus species and was likely spread via the pet trade. The marbled crayfish is a triploid hybrid, very likely created in captivity, and is entirely parthenogenetic. After escaping from captivity, it has since spread to become invasive in many European countries as well as in Madagascar.

Mallet cites Gutekunst and colleagues (2018) to support this. But they specifically said, “We do not think Marmorkrebs is a hybrid.”

Alternative hypotheses involving allopolyploid formation with P. alleni appear unlikely due to the lack of hybrid morphological features and the considerable genetic differences.

And it’s not just them. Vogt and colleagues (2016) wrote:

The morphological features and microsatellite patterns strongly suggest that marbled crayfish originated by autopolyploidisation and not by hybridisation with a closely related species, which is by far the most frequent cause of triploidy in animals.

There is some overlap in the author lists of Gutekunst et al. (2018) and Vogt et al. (2016). Having the some of the same authors makes it not surprising that the two papers reach the same conclusions. But they are not the only ones. Martin and colleagues (2016) reached the same conclusion:

Martin et al. (2010) suggested that the Marmorkrebs originated directly from sexual P. fallax without hybridization.

Our data tentatively support this conclusion. Based on the assumption of a hybridization between P. fallax and P. alleni, one would expect that the numerically different karyotypes of these two species would have led to a chromosome number higher than that counted in Marmorkrebs. Furthermore, a preliminary comparison of the nuclear protein coding histone H3 gene (H3) and the nuclear elongation factor 2 gene (EF-2) revealed at least seven polymorphic positions within the EF-2 intron that suggest a non-hybrid origin of the Marmorkrebs.


For a very long time, I would have bet money that Marmorkrebs was a hybrid, because so many cases of asexual reproduction trace back to hybridization events. All of the papers above go on to say that, strictly speaking, there is still a very slight possibility that Marmorkrebs is a hybrid. But hybridization isn’t the way to bet any more.

References

Gutekunst J, Andriantsoa R, Falckenhayn C, Hanna K, Stein W, Rasamy J, Lyko F. 2018. Clonal genome evolution and rapid invasive spread of the marbled crayfish. Nature Ecology & Evolution 2(3): 567–573. https://doi.org/10.1038/s41559-018-0467-9

Mallet J. 2018. Invasive insect hybridizes with local pests. Proceedings of the National Academy of Sciences: in press. https://doi.org/10.1073/pnas.1804081115

Martin P, Thonagel S, Scholtz G. 2016. The parthenogenetic Marmorkrebs (Malacostraca: Decapoda: Cambaridae) is a triploid organism. Journal of Zoological Systematics and Evolutionary Research 54(1): 13-21. http://dx.doi.org/10.1111/jzs.12114

Vogt G, Falckenhayn C, Schrimpf A, Schmid K, Hanna K, Panteleit J, Helm M, Schulz R, Lyko F. 2015. The marbled crayfish as a paradigm for saltational speciation by autopolyploidy and parthenogenesis in animals. Biology Open 4(11): 1583-1594. http://dx.doi.org/10.1242/bio.014241



10 April 2018

Maughan, 2018

Maughan M. 2018. Cyclical parthenogenesis in crustaceans. Poster presentation, Utah State University, 12 April 2018. https://digitalcommons.usu.edu/researchweek/ResearchWeek2018/All2018/283/


Abstract


Apomixis is the replacement of sexual reproduction with asexual reproduction in plants. Some scientists hypothesize that apomixis is caused by genetics that evolved after sexual reproduction and apomixis mutated from sexual reproduction. However, we hypothesize that sexual reproduction and apomixis evolved simultaneously during eukaryogenesis, the evolution of eukaryotic life. We think that most organisms retain the capacity for apomixis and sexual reproduction in their genome. Many taxa, including plants and crustaceans, should have a single genome able to express both sexual and asexual reproduction as long as the correct metabolic signaling is provided to the germline cells. In Professor John Carman’s lab, researchers have successfully induced onset of apomixia in sexual plants. These successes support our hypothesis and suggest that some animals could also have the pathogenesis and sexual reproduction capabilities in their genome. The equivalent of plant apomixis in animals is apomictic parthenogenesis. We focus on cyclical parthenogenesis. In cyclical parthenogenesis animals alternate between sexual and asexual reproduction. Daphnia magna and Procambarus virginalis (marbled crayfish) are both cyclically parthenogenetic. The TOR (rapamycin complex 1) signaling pathway in plants and animals is a regulator of cell growth and it affects the pathway of reproduction. Oxidative stress turns off the TOR signaling pathway and turns SnRK1(SNF1-related kinase 1 in yeast and AMPK in animals) on. SnRK1 makes cells begin the process of sexual reproduction. To test this hypothesis, I will be researching how to switch asexual organisms to reproduce sexually. I will inject the ovaries of crayfish with chemicals designed to alter their glucose levels and place the Daphnia in a solution containing the appropriate chemicals. The presence of an egg sack from the Daphnia and the presence of male crayfish will show the success of the expirement (sic).

Keywords: None provided.

02 April 2018

Neff, 2018

Neff EP. 2018. The Marmorkrebs model. Lab Animal 47(4): 107-107. https://doi.org/10.1038/s41684-018-0030-y

Abstract

Without abstract. First paragraph:

In his lab at the German Cancer Research Center in Heidelberg, Frank Lyko studies epigenetics, how the environment can change an organism’s phenotype without altering its underlying DNA. About 15 years ago, a colleague introduced him to the marbled crayfish, a triploid, clonal, parthenogenic, and only very recently speciated invertebrate that’s proven to be quite the invasive pest across the globe. At the time, the Marmorkrebs (as it’s known in German) didn’t register in Lyko’s research plans. But recently, he began thinking about alternative models. Classical laboratory animals, like mice, worms, and fruit flies, “always have the same phenotype, and if you induce a genetic mutation you get one aberrant phenotype normally,” he explains. “This is super helpful if you do genetic research but it’s not necessarily good for describing what’s going on in epigenetics.” He tried honeybees, but found them challenging to keep in the laboratory. His lab wasn’t fond of another potential epigenetic model, the African desert locust, either. “These were really big animals and they were always escaping and flying around, so that was a mess,” he recalls. “Then I remembered my old conversation with Günter Vogt.”

Keywords: None provided.

30 March 2018

Why people can’t take invasive crayfish seriously

In compiling the news coverage and reactions to the Marmorkrebs genome sequence (which is still trickling in), I’ve noticed a common reaction. The story describes Marmorkrebs as an invasive, outlines the problem, and someone shows up in the comments saying something like, “Mmmm. Gumbo!” or “Get the melted butter ready,” or something like that.

Jokes like that show pretty clearly that people think invasive crayfish are a joke, and nothing to worry about. And as much as I love the Non Sequiter cartoon about Marmorkrebs, it also uses the problem for comedy.

“Eat them all” is not an attitude unique to North America:

This novel perspective on invasive species was perhaps most elegantly stated as we made small talk with a taxi driver in Wuhan. As we explained our research through an interpreter, the taxi driver smiled and asked, “Can they really be considered a problem if people eat them?”

This attitude is perhaps more understandable in China, given that “Chinese food” in China means “crayfish” more than General Tso’s chicken. Louisiana red swamp crayfish are the most popular restaurant dish, and that makes for a $22 billion (yes, with a “B”) market.

But there are at least two problems with the “We can eat them” attitude. First, people don’t understand that there are differences in commercial viability. Marmorkrebs are small compared to Louisiana red swamp crayfish, meaning that you are expending more effort for less meat. It’s like saying, “Hey, Asian carp are fish, we can eat fish, no problem,” without realizing that they’re bony, and not many people want to eat carp. (This may not be an insurmountable problem, though.)

Similarly, not everyone wants to eat crayfish. My understanding that in some places, suggesting that people eat crayfish goes over about as well as suggesting people in the United States eat cockroaches.

But the other problem is that while it sounds good in theory, there’s not a lot of evidence that introducing commercial harvest for invasives will get rid of the problem. Barbour and colleagues (2011) looked at the prospect of controlling lionfish by fishing them for food. They concluded:

(C)omplete eradication of lionfish through fishing is unlikely, and substantial reduction of adult abundance will require a long-term commitment and may be feasible only in small, localized areas where annual exploitation can be intense over multiple consecutive years.

A later paper (de Leon and colleagues, 2013) reached similar conclusions:

While removal efforts are effective at reducing the local number of lionfish, recruitment from unfished locations, such as those too deep for recreational diving and at dive sites that are difficult to access, will continuously offset the effects of removal efforts.

Still, some are continuing to investigate this for lionfish (Chapman et al. 2016).

Indeed, creating commerical fisheries for aquatic invasives probably increases the problems, since you now have incentives to perform even more introductions (Nuñez and colleagues, 2012; Pasko and Goldberg 2014), even through the track record is poor. Establishing commericial fisheries for crayfish was one of the main reason North American species were introduced in many European countries decades ago (e.g., Sweden), and they have since realized that they are causing far more problems than they made money.

If we are going to stop introductions of non-native crayfish, we are going to have to convince people that the problem is serious. Jokes about food show they aren’t there yet.

References

Barbour AB, Allen MS, Frazer TK, Sherman KD. 2011. Evaluating the potential efficacy of invasive lionfish (Pterois volitans) removals. PLOS ONE 6(5): e19666. https://doi.org/10.1371%2Fjournal.pone.0019666

Chapman JK, Anderson LG, Gough CLA, Harris AR. 2016. Working up an appetite for lionfish: A market-based approach to manage the invasion of Pterois volitans in Belize. Marine Policy 73: 256-262. http://www.sciencedirect.com/science/article/pii/S0308597X16304857

de León R, Vane K, Bertuol P, Chamberland VC, Simal F, Imms E, Vermeij MJA. 2013. Effectiveness of lionfish removal efforts in the southern Caribbean. Endangered Species Research 22(2): 175-182. http://www.int-res.com/abstracts/esr/v22/n2/p175-182/

Nuñez MA, Kuebbing S, Dimarco RD, Simberloff D. 2012. Invasive species: to eat or not to eat, that is the question. Conservation Letters 5(5): 334-341. https://doi.org/10.1111/j.1755-263X.2012.00250.x

Pasko S, Goldberg J. 2014. Review of harvest incentives to control invasive species. Management of Biological Invasions 5(3): 263–277. https://doi.org/10.3391/mbi.2014.5.3.10

Related posts

Marmorkrebs genome news round-up

External links

Louisiana crayfish: good, bad, and delicious
The economy of crayfish
Non Sequiter cartoon: Crayfish apocalypse
Eat The Enemy: The Delicious Solution To Menacing Asian Carp

Picture from here.

26 March 2018

The crayfish apocalypse

Of over a hundred news articles, blog posts, and other miscellaneous things I have seen on the Internet about Marmorkrebs since the genome paper came out, this Non Sequiter comic by Wiley may be my favourite of all of them. And that includes articles that quoted me or used my Marmrorkrebs picture.

Click here to read it.

Hat tip to James Murray.

22 February 2018

Gutekunst and colleagues, 2018

Gutekunst J, Andriantsoa R, Falckenhayn C, Hanna K, Stein W, Rasamy J, Lyko F. 2018. Clonal genome evolution and rapid invasive spread of the marbled crayfish. Nature Ecology and Evolution 2(3): 567–573. https://doi.org/10.1038/s41559-018-0467-9

Abstract

The marbled crayfish Procambarus virginalis is a unique freshwater crayfish characterized by very recent speciation and parthenogenetic reproduction. Marbled crayfish also represent an emerging invasive species and have formed wild populations in diverse freshwater habitats. However, our understanding of marbled crayfish biology, evolution and invasive spread has been hampered by the lack of freshwater crayfish genome sequences. We have now established a de novo draft assembly of the marbled crayfish genome. We determined the genome size at approximately 3.5 gigabase pairs and identified > 21,000 genes. Further analysis confirmed the close relationship to the genome of the slough crayfish, Procambarus fallax, and also established a triploid AA’B genotype with a high level of heterozygosity. Systematic fieldwork and genotyping demonstrated the rapid expansion of marbled crayfish on Madagascar and established the marbled crayfish as a potent invader of freshwater ecosystems. Furthermore, comparative whole-genome sequencing demonstrated the clonality of the population and their genetic identity with the oldest known stock from the German aquarium trade. Our study closes an important gap in the phylogenetic analysis of animal genomes and uncovers the unique evolutionary history of an emerging invasive species.

Keywords: comparative genomics • evolutionary genetics • invasive species