Tag Archives: varia

WSWH2

This cryptic code refers to the paper ‘World Scientists’ Warning to Humanity: A Second Notice’ that appeared yesterday in BioScience.

The authors have been able to mobilise more than 15,000 scientists from 184 countries across the world to endorse this paper, which gives a brief summary of major trends since the first ‘Warning’ in 1992. Still a lot remains to do, and civil-society pressure and evidence-based advocacy is needed to push (political and societal) leadership into sustainability transitions.

Warning-to-Humanity-comp1-web-text

Any scientist that did not sign the article before the BioScience publication deadline, is invited to endorse it now after publication by visiting (scientists.forestry.oregonstate.edu). Therefore, feel free to invite any of your scientist contacts to join in now by signing the article.

The voice of world scientists is essential in driving forward progress on dealing with climate change and other critical environmental trends. Working together, we can make great progress in preserving the biosphere for the sake of humanity.

 

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Achatina fulica: effectiveness of removal methods

The Giant African Snail, Achatina fulica (or Lissachatina f.) is difficult to eradicate once established. This species was introduced in several South American countries and several researchers have made studies on its distribution and possible eradication. One of such studies is by Garcés-Restrepo et al. (2016).

The presence of the giant African snail Achatina fulica (Bowdich 1822) was confirmed in Colombia in 2008. Due to economic and health implications of this species and the difficulties in controlling it, it is essential to establish the relevance of protocols and alternative inexpensive substances used to control the snail. In this research, the effectiveness of manual removal and manual removal with spray of calcium oxide was analyzed. Both techniques had similar efficiencies, so it is recommended that calcium oxide should be implemented only for the disposal of the collected individuals in order to reduce costs and decrease the impact on arthropofauna. In addition, we evaluated the molluscicide ability of commercial sodium hypochlorite, two plant extracts (Tabebuia rosea and Jatropha curcas), and commercial molluscicide (metaldehyde). We found that the three alternative substances were effective as molluscicides, but with lower effectiveness than the commercial substance. Implementation of the extracts of T. rosea and J. curcas is recommended because they have low cost, and do not present negative effects on the environment”.

Reference:
Garcés-Restrepo, M. et al., 2016. Sustancias alternativas para el control del caracol africano (Achatina fulica) en el Valle del Cauca, Colombia. – Biota Colombiana, 17: 44-52.

Morphometrics using photographs

In many cases morphometric studies are done taking landmarks using photographs. There appears to be of distortion, which has been studied in the recent paper by Collins & Gazley (2017).

Most geometric morphometric studies are underpinned by sets of photographs of specimens. The camera lens distorts the images it takes, and the extent of the distortion will depend on factors such as the make and model of the lens and camera and user-controlled variation such as the zoom of the lens. Any study that uses populations of geometric data digitized from photographs will have shape variation introduced into the data set simply by the photographic process. We illustrate the nature and magnitude of this error using a 30-specimen data set of Recent New Zealand Mactridae (Mollusca: Bivalvia), using only a single camera and camera lens with four different photographic setups. We then illustrate the use of retrodeformation in Adobe Photoshop and test the magnitude of the variation in the data set using multivariate Procrustes analysis of variance. The effect of photographic method on the variance in the data set is significant, systematic, and predictable and, if not accounted for, could lead to misleading results, suggest clustering of specimens in ordinations that has no biological basis, or induce artificial oversplitting of taxa. Recommendations to minimize and quantify distortion include: (1) that studies avoid mixing data sets from different cameras, lenses, or photographic setups; (2) that studies avoid placing specimens or scale bars near the edges of the photographs; (3) that the same camera settings are maintained (as much as practical) for every image in a data set; (4) that care is taken when using full-frame cameras; and (5) that a reference grid is used to correct for or quantify distortion”.

There is more that can be wrong than one can suspect, so this might be a useful study for those who are applying morphometrics in their taxonomical work.

Reference:
Collins, K.S. & Gazley, M.F., 2017. Does my posterior look big in this? The effect of photographic distortion on morphometric analyses. – Paleobiology, 43: 508-520.

Euthanasia techniques for snails

Collecting snails in the field or bringing them into the laboratory often results in killing and preserving the animals. Gilbertson & Wyatt (2016) have evaluated several techniques for doing so.

The euthanasia of invertebrates used in scientific investigations poses unanswered questions regarding the rapid induction of unconsciousness with minimal distress and pain. Relative to vertebrates, invertebrates’ sensory experience of pain, nociception, and physiologic response to aversive stimuli are poorly characterized. The scientific communities in the European Union, Canada, United States, Australia, and New Zealand join in consensus regarding the need to address alleviation of pain and distress in cephalopods (octopus, squid, and so forth), which have the best-characterized nervous system among invertebrates. In the current study, we evaluated various euthanasia techniques in a terrestrial gastropod species, with priority on animal wellbeing, scientific variability, feasibility in both field and laboratory settings, and acceptability by personnel. In addition, we demonstrated that the 2-step method of euthanasia described in the AVMA Guidelines as acceptable for aquatic invertebrates is effective for terrestrial snails and meets all welfare and scientific requirements. This 2-step method first induces anesthesia by immersion in 5% ethanol (laboratory-grade ethanol or beer) followed by immersion in a euthanizing and tissue-preserving solution of 70% to 95% ethanol or 10% neutral buffered formalin. Furthermore, alternative methods of euthanasia for terrestrial snails commonly used in field research, such as live immersion in concentrated ethanol or formalin, were shown to be unacceptable”.

For sure, the acceptance of beer will be welcomed by many field workers…

Reference:
Gilbertson, C.R. & Wyatt, J.D., 2016. Evaluation of euthanasia techniques for an invertebrate species, land snails (Succinea putris). – Journal of the American Association for Laboratory Animal Science, 55: 577-581.

Using microwaves to prepare gastropods

Today time for a tidbit about methodology and techniques. Already published some years ago, Galindo et al. (2014) provide a nice study about the use of microwaves to remove snails from their shells and the possible effect on DNA research of the animals.

Extracting DNA from gastropods presents particular difficulties due to the capacity of the living animal to retract into the shell, resulting in poor penetration of the ethanol into the tissues. Because the shell is essential to establish the link between sequences and traditional taxonomic identity, cracking the shell to facilitate fixation is not ideal. Several methods are currently in routine use to overcome this difficulty, including chemical relaxation, drilling the shell and boiling. Most of these methods are time-consuming, may be safety hazards and constitute a bottleneck in the preparation of large numbers of specimens in the field. We have experimented with a method traditionally used to clean shells that involves placing the living gastropods in a microwave (MW) oven; the electromagnetic radiation very quickly heats both the animal and the water trapped inside the shell, resulting in separation of the muscles that anchor the animal to the shell. Done properly, the body can be removed intact from the shell and the shell voucher is preserved undamaged. To test the method, the bodies of live-collected specimens from two gastropod species were separated from their shell by microwaving and by anesthetizing/drilling. After identical extraction and PCR procedures, the gels showed no difference in DNA quantity or quality, and the resulting sequences are identical within species. The method was then implemented on a large scale during expeditions, resulting in higher percentage of DNA extraction success. The MWs are also effective for quickly and easily removing other molluscs from their shells, that is, bivalves and scaphopods. Workflows implementing the MW technique show a three- to fivefold increase in productivity compared with other methods”.

This is an interesting method for those wanting to prepare material for DNA research and who have the equipment available during field work. Note that the authors are usually part of full-fletched expeditions with much more facilities than the average field worker. One disadvantage, also mentioned in the paper, of the procedure is its unsuitability for ethanol-preserved material. That is a pity, since material from collections is usually difficult to remove from their shells.

 

Reference:
Galindo, L. et al., 2014. Using microwaves to prepare gastropods for DNA barcoding. – Molecular Ecology Resources, 14: 700-705.

Adaptive significance of arboreality

Seaki et al. (2017) have recently published the results of a field experiment in which they tested the survival advantages of living in a tree.

Arboreality has evolved in a wide range of taxa, but its adaptive significance has rarely been examined in natural ecosystems. Euhadra brandtii sapporo is an arboreal land snail distributed in a restricted area of Hokkaido, Japan. We hypothesized that arboreality provides the species with significant survival advantages, which we tested via field observations and experiments. A monitoring census showed that E. b. sapporo hibernates in winter in the ground litter, climbs into the canopy in early spring and returns to the ground in late autumn. This seasonal movement appears to be effective for escaping from predation by ground-dwelling carabine beetles, whose activity was high during the summer based on a pitfall-trap census. Manipulative field experiments were conducted to compare survival rates in arboreal and ground-dwelling environments. We collected 120 E. b. sapporo individuals in summer and tethered 40 in tree canopies and 80 on the ground; half those on the ground were covered by baskets to prevent predation by large animals. The survival rate after 11 days was highest in the canopy, followed by that on the ground with a basket and was lowest on the ground without a basket. Predation was the main cause of death, but some died from other causes. Similar results were obtained in autumn, except for higher survival rates of the ground treatments. Analyses of carbon and nitrogen isotope ratios suggest that the land snail uses epiphytic lichens and mosses as food resources. In conclusion, arboreality has a marked advantage in reducing mortality in E. b. sapporo and is probably supported by food availability as well”.

This seems a very well-conducted experiment which may have more general significance for other snail families with arboreal members around the world.

Reference:
Saeki, I. et al., 2017. Adaptive significance of arboreality: field evidence from a tree-climbing land snail. – Animal Behaviour, 127: 53-66.

 

Bourguignat letters

A new paper was just published which sheds some light on the controversy between Bourguignat and Crosse during the last half of the 19th century. This is a publication of the project on the history of European malacology.

Reference:
Audibert, C., Backhuys, W. & Breure, A.S.H., 2017. ‘Une petite histoire malacologique’: two letters from Bourguignat to Crosse, or a story of friction between malacologists. – Journal of Conchology, 42: 407–411.