After 20 years, what have we learned?... Read more »
Strayer, D. (2009) Twenty years of zebra mussels: lessons from the mollusk that made headlines. Frontiers in Ecology and the Environment, 7(3), 135-141. DOI: 10.1890/080020
Acinetobacter baumanii is a pathogenic bacterium that has been demonstrated to cause pneumonia, skin infections, and secondary meningitis, predominantly in a health-care facility setting. Its ability to form biofilms on inert surfaces is instrumental in creating reservoirs for opportunistic infection.... Read more »
Jacobs, A. et al. (2010) Inactivation of Phospholipase D Diminishes Acinetobacter baumannii Pathogenesis. Infection and Immunity, 78(5), 1952-1962. DOI: 10.1128/IAI.00889-09
For at least 30 million years, bone-eating worms have been making their homes in the bodies of decomposing whales on the seabottom, but the rotting cetacean carcasses are not just food sources for the polychaetes.
The term "worm" immediately conjures up images of the red, squiggly things which crawl all over the sidewalk after it rains, but this imagery does not fit the boneworms of the genus Osedax. These worms start off life as sexless larvae, and the timing of their arrival at a whale corpse makes all the difference as to whether they will be male or female. If the larva lands on the bones of a whale first, it will grow into a large female which will digest the bone with the help of endosymbiotic bacteria which comes to live inside the worm. Once this starts to happen, the larvae which fall on the already-established females will have a different life history. They will become males and will remain tiny (0.2-1.0mm long) for the rest of their lives, accumulating in crowded harems inside the tube of the larger female and living off stored yolk from their younger days as they have no mouth or digestive tract to speak of. Read the rest of this post... | Read the comments on this post...... Read more »
VRIJENHOEK, R., JOHNSON, S., & ROUSE, G. (2008) Bone-eating females and their ‘harems’ of dwarf males are recruited from a common larval pool . Molecular Ecology, 17(20), 4535-4544. DOI: 10.1111/j.1365-294X.2008.03937.x
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Rode, K., Amstrup, S., & Regehr, E. (2010) Reduced body size and cub recruitment in polar bears associated with sea ice decline. Ecological Applications, 20(3), 768-782. DOI: 10.1890/08-1036.1
Weta is not just the name of a special effects studio; it’s the common name for one very large insect (pictured) that is found in New Zealand. Like many animals on New Zealand, it’s under a bit of pressure from introduced mammals, so there are definitely conservation implications if you can understand the mating system of the animal.
Wetas make an interesting case study for studying body size and mating, because they are large for their lineage, and there’s also a big size difference between the males and the females. In this particular species of weta (Deinacrida rugosa), females are about twice as heavy as males.
There’s a lot of permutations and combinations to figure out what factors are important in mating in these species. Having a large body can have a lot of advantages in the mating game. It can help you compete with other members of the same sex in a physical contest. But another way being large can help you compete is that bigger bodies can often mean bigger reproductive organs, and more gametes, which for males translates to more sperm. Is having a large body size advantageous in either sex?
Four years of chasing wetas in New Zealand, radio-tagging them (yes, they’re big enough for radio tags), letting them copulate in buckets and burrows, and authors Kelly and company are getting closer to some answers.
Somewhat unexpectedly, they did not find any statistically significant relationship between body size of mating wetas. Big boys didn’t mate with big girls or small with small.
Second, heavy females received significantly less sperm than light females. This is again a bit unexpected, given that in invertebrates, large females almost always are able to produce more offspring. Typically, you find males will expend as much sperm on the highest quality females as possible. Additionally, male body size doesn’t limit how much sperm the males can produce, so there was no evidence of “the spirit is willing but the flesh is weak.”
Why? One possibility is that weta males just don’t adjust their sperm allocation for mate quality. If so, this would be very surprising, given how often males in how many different species have been shown to be able to do this. Maybe female size isn’t an indicator of fecundity, though that also seems a bit hard to believe.
The authors also float the idea that large females are so sexually attractive, that males act as if they “assume” large, high quality females will be mated multiple times, and they produce less sperm so as not to “over-invest” in a competetive situation. The authors admit themselves that their data don’t support that; there isn’t a statistically significant relationship.
Kelly, C., Bussière, L., & Gwynne, D. (2010). Pairing and insemination patterns in a giant weta (Deinacrida rugosa: Orthoptera; Anostostomatidae) Journal of Ethology DOI: 10.1007/s10164-010-0211-7
Photo by mollivan_laura on Flickr. Used under a Creative Commons license.
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Kelly, C., Bussière, L., & Gwynne, D. (2010) Pairing and insemination patterns in a giant weta (Deinacrida rugosa: Orthoptera; Anostostomatidae). Journal of Ethology. DOI: 10.1007/s10164-010-0211-7
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Roberts, S., Jordan, J., Bettinger, P., & Warren, R. (2010) Using Bobcat Habitat Suitability to Prioritize Habitat Preservation on a Suburbanizing Barrier Island. Journal of Wildlife Management, 74(3), 386-394. DOI: 10.2193/2008-431
Since I’ve been talking about the possibility of admixture with “archaics” (I’m starting to think the term is a bit too H. sapiens sapiens-centric, is the Neandertal genome turning out to have more ancestral alleles?) I thought I’d point to a paper out in PLoS ONE which reiterates the basic fact that the overwhelming genetic [...]... Read more »
Laval G, Patin E, Barreiro LB, Quintana-Murci. (201) Formulating a Historical and Demographic Model of Recent Human Evolution Based on Resequencing Data from Noncoding Regions. PLoS One. info:/10.1371/journal.pone.0010284
...they wear big exoskeletons.
Today's Friday Weird Science comes to you courtesy of the talented, handsome, and soon to be no longer stranded in Australia (hopefully), Ed of Not Exactly Rocket Science. Because no one can tell you more about beetles and the size of their...mandibles...than Ed. :)
Yamane et al. "Dispersal and ejaculatory strategies associated with exaggeration of weapon in an armed beetle" Proceedings of the Royal Society B, 2009.
And here we have today's male of choice:
(Is that a hottie or what?!)
Read the rest of this post... | Read the comments on this post...... Read more »
Yamane, T., Okada, K., Nakayama, S., & Miyatake, T. (2010) Dispersal and ejaculatory strategies associated with exaggeration of weapon in an armed beetle. Proceedings of the Royal Society B: Biological Sciences. DOI: 10.1098/rspb.2009.2017
More genetic and other studies of long-lived people are taking place these days, which means a faster flow of results than has been the case in past years. Part of that can no doubt be attributed to an increased interest in manipulating the aging process in the scientific community, as well as the continually falling cost of the tools needed to run such studies. While perusing PubMed recently, I noticed a few new reports from ongoing longevity studies starting with one from the Leiden Study in the Netherlands, which you might recall produced some interesting results on thyroid hormones and human longevity last year. Here's the paper: Favorable glucose tolerance and lower prevalence of metabolic syndrome in offspring without diabetes mellitus of nonagenarian siblings: the Leiden longevity study. Despite similar body composition, the offspring of nonagenarian siblings showed a lower prevalence of metabolic syndrome and better glucose tolerance than their partners, centralizing the role of favorable glucose metabolism in familial longevity. Next, another association between heat shock proteins (HSPs) and longevity. Heat shock proteins are becoming a hot field of study, as is true of all things related to autophagy, the collection of processes by which cells recycle damaged components....... Read more »
Rozing MP, Westendorp RG, de Craen AJ, Frölich M, de Goeij MC, Heijmans BT, Beekman M, Wijsman CA, Mooijaart SP, Blauw GJ.... (2010) Favorable glucose tolerance and lower prevalence of metabolic syndrome in offspring without diabetes mellitus of nonagenarian siblings: the Leiden longevity study. Journal of the American Geriatrics Society, 58(3), 564-9. PMID: 20398121
Singh R, Kølvraa S, Bross P, Christensen K, Bathum L, Gregersen N, Tan Q, & Rattan SI. (2010) Anti-inflammatory heat shock protein 70 genes are positively associated with human survival. Current pharmaceutical design, 16(7), 796-801. PMID: 20388090
Laplana M, Sánchez-de-la-Torre M, Aguiló A, Casado I, Flores M, Sánchez-Pellicer R, & Fibla J. (2010) Tagging long-lived individuals through vitamin-D receptor (VDR) haplotypes. Biogerontology. PMID: 20407924
Although the root cause(s) of stuttering remain unknown, evidence has accumulated from twin and adoption studies that genetics plays a role. A recent study identified several genes mutated in people with the disorder, including one that has never been previously associated with any human malady.... Read more »
Kang C, Riazuddin S, Mundorff J, Krasnewich D, Friedman P, Mullikin JC, & Drayna D. (2010) Mutations in the lysosomal enzyme-targeting pathway and persistent stuttering. The New England journal of medicine, 362(8), 677-85. PMID: 20147709
In 1960, Mary Leaky discovered a set foot bones composed of seven tarsals (in your ankle) and five metatarsals (in the area between your ankle and your toes). These bones are those of a biped, with the joints reflecting an in-line big toe. For these bones, the surrounding debate hasn’t been over whether or not [...]... Read more »
Suppose you’re a caterpillar. You’ve just built yourself a nice home by sewing leaves together with silk and then some jackass invades your turf. How do you defend your home? You could walk right over to that intruder and push him, maybe smack him around a bit or even bite him. Ha! That’d teach [...]... Read more »
Scott, J., Kawahara, A., Skevington, J., Yen, S., Sami, A., Smith, M., & Yack, J. (2010) The evolutionary origins of ritualized acoustic signals in caterpillars. Nature Communications, 1(1), 1-9. DOI: 10.1038/ncomms1002
The evaluation of large scale scenarios for alternative energy production are exercises in making trade-offs. If the U.S. devotes substantial resources to ethanol production then use of fossil fuels may be reduced, diminishing dependence on foreign oil, in theory. But are there other costs and benefits? Currently ethanol production in the U.S. centers around corn … Read more... Read more »
Piñeiro, G., Jobbágy, E., Baker, J., Murray, B., & Jackson, R. (2009) Set-asides can be better climate investment than corn ethanol. Ecological Applications, 19(2), 277-282. DOI: 10.1890/08-0645.1
Two papers in Nature this month leverage the power of second-generation sequencing technologies to investigate gene expression variation in human cell lines. By performing RNA-Seq in HapMap cell lines, the authors generated the most extensive gene expression data to date for these samples, and were able to use publicly available HapMap genotypes to associate expression [...]... Read more »
Pickrell JK, Marioni JC, Pai AA, Degner JF, Engelhardt BE, Nkadori E, Veyrieras JB, Stephens M, Gilad Y, & Pritchard JK. (2010) Understanding mechanisms underlying human gene expression variation with RNA sequencing. Nature, 464(7289), 768-72. PMID: 20220758
Montgomery SB, Sammeth M, Gutierrez-Arcelus M, Lach RP, Ingle C, Nisbett J, Guigo R, & Dermitzakis ET. (2010) Transcriptome genetics using second generation sequencing in a Caucasian population. Nature, 464(7289), 773-7. PMID: 20220756
A new study shows that chimps sacrifice their own advantage if they earned it unfairly.Image: Owen Booth / Creative Commons
Fairness is the basis of the social contract. As citizens we expect that when we contribute our fair share we should receive our just reward. When social benefits are handed out unequally or when prior agreements are not honored it represents a breach of trust. Based on this, Americans were justifiably outraged when, not just one, but two administrations bailed out the wealthiest institutions in the country while tens of thousands of homeowners (many of whom were victims of these same institutions) were evicted and left stranded. It smacked of favoritism, the corruption of politics by corporate money, and it was also just plain unfair. But isn't that the way the world works? Isn't it true, as we were so often told as children, that life is unfair?
The American financial tycoon Andrew Carnegie certainly thought so and today's economic elite have followed his example. In 1889 he used a perverted form of Darwinism to argue for a "law of competition" that became the cornerstone of his economic vision. His was a world in which might made right and where being too big to fail wasn't a liability, it was the key to success. In his Gospel of Wealth, Carnegie wrote that this natural law might be hard for the least among us but "it ensures the survival of the fittest in every department."
We accept and welcome therefore, as conditions to which we must accommodate ourselves, great inequality of environment, the concentration of business, industrial and commercial, in the hands of a few, and the law of competition between these, as being not only beneficial, but essential for the future progress of the race.
In other words, his answer was yes. Life is unfair and we'd better get used to it, social contract or no social contract.
While this perspective may be common among those primates who live in the concrete jungle of Wall Street, it doesn't hold true for the natural world more generally. Darwin understood that competition was an important factor in evolution, but it wasn't the only factor. Cooperation, sympathy, and fairness were equally important features in his vision for the evolution of life. In The Descent of Man he wrote that "Those communities which included the greatest number of the most sympathetic members would flourish best, and rear the greatest number of offspring." By working cooperatively, by sharing resources fairly, and by ensuring that all members of society benefited, Darwin argued that early human societies would be more "fit" than those societies where members only cared about themselves. The Russian naturalist Peter Kropotkin championed this aspect of Darwin's work and argued that mutual aid was essential for understanding the evolution of social mammals as a whole. In the time of Darwin and Kropotkin the research needed to verify these claims was in its infancy, but recent work has supported this vision of the natural world. Now, a new study has added one more plank to this growing edifice of knowledge, and the view from on top suggests that life, in contrast to what Carnegie believed, may not be so unfair after all. Read the rest of this post... | Read the comments on this post...... Read more »
Brosnan, S., Talbot, C., Ahlgren, M., Lambeth, S., & Schapiro, S. (2010) Mechanisms underlying responses to inequitable outcomes in chimpanzees, Pan troglodytes. Animal Behaviour. DOI: 10.1016/j.anbehav.2010.02.019
A Madagascar sucker-footed bat (Myzopoda aurita).
In the tropical forests of Madagascar, there lives a very peculiar kind of bat. While most bats roost by hanging upside-down from cave ceilings or tree branches, the Madagascar sucker-footed bat (Myzopoda aurita) holds itself head-up thanks to a set of adhesive pads on its wings. Nor is it the only bat to do so. Thousands of miles away in the jungles of Central and South America, Spix's disk-winged bat (Thyroptera tricolor) does the same thing, but how do their sucker pads work, and why do they choose to roost in a different way from all other bats?
Read the rest of this post... | Read the comments on this post...... Read more »
RISKIN, D., & RACEY, P. (2010) How do sucker-footed bats hold on, and why do they roost head-up?. Biological Journal of the Linnean Society, 99(2), 233-240. DOI: 10.1111/j.1095-8312.2009.01362.x
Recently, I read a statement by the American Heart Association about Alcohol, saying that although moderate alcohol reduces your risk of stroke, if you don't already drink you should not begin drinking because drinking raises your risk of cancer. This is an interesting statement, because I think it is incorrect. Cancer is rare, Stroke is common. Even though alcohol increases the probability of ... Read more »
Fig. 5. Boundary of the Hopf bifurcation of the endemic steady state … 1
I don’t pretend to be a mathematician or to understand the more complex disease models that are out there, but I do think modeling is an essential way of understanding how to effectively deal with diseases. A recent paper1 looks at epidemic [...]... Read more »
Blyuss, K., & Kyrychko, Y. (2009) Stability and Bifurcations in an Epidemic Model with Varying Immunity Period. Bulletin of Mathematical Biology, 72(2), 490-505. DOI: 10.1007/s11538-009-9458-y
Around 160 million years ago, an enormous sauropod dinosaur trudged across an ancient marsh in what is now Xinjiang, China. It was not easy going. The eruption of a nearby volcano coated the area in a layer of ash which formed a thin surface over a morass of mud and volcanic debris, and as it [...]... Read more »
Researchers from Queensland University have discovered a new way to administer vaccines, a Nanopatch. Smaller than a postage stamp, the patch puts the vaccine through your skin. No need for an injection.
So how does it work?
The Nanopatch is full of micro-nanoprojections containing antigen – part of the bacteria or virus you are immunising [...]... Read more »
Crichton, M., Ansaldo, A., Chen, X., Prow, T., Fernando, G., & Kendall, M. (2010) The effect of strain rate on the precision of penetration of short densely-packed microprojection array patches coated with vaccine. Biomaterials, 31(16), 4562-4572. DOI: 10.1016/j.biomaterials.2010.02.022
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