A sampling of the latest science papers. Forthwith: the masturbation strategies of African squirrels; Houston, we have a sinking problem; yes, mushrooms cooperate, sort of; and new-found form of GM stream pollution.
- Northwest Houston is sinking rapidly—by as much as 2 inches a year, according to a new paper in Tectonophysics. The reason: groundwater withdrawal, a practise that's ceased in most of the Houston area, yet continues in the northwest, where rapid population growth continues. The problem's not new. The Brownwood neighborhood was developed in the 1930s when ground elevation was 3 meters/10 feet above sea level. Forty years later, the neighborhood stood just half a meter above sea level and was subject to frequent flooding. Hurricane Alicia destroyed the subdivision in 1983, after which the area became the Baytown Nature Center. Brownwood's sinking is attributed to the massive groundwater withdrawal by petrochemical plants along the Houston Ship Channel.
- Mushroom spores cooperate. Really. New research in PNAS finds that forcibly ejected spores of some fungi, including the pathogen Sclerotinia sclerotiorum, disperse with astonishing rapidity. By synchronizing the ejection of thousands of spores, these fungi create their own airflow, which carry the spores through nearly still air, around obstacles, and into atmospheric currents (therefore to new infection sites). Although many spores are sacrificed to produce the favorable airflow (creating the potential for conflict between spores), the geometry of the spore jet physically benefits those spores that cooperate maximally in its production. Synchronized spore ejection may prove a model for the evolution of stable self-organized behaviors. High-speed imaging shows synchronization is self-organized and likely triggered by mechanical stresses.
- Streams in the midwest are receiving insecticidal proteins from genetically modified crops. The authors assessed 217 stream sites in Indiana and found dissolved insecticidal proteins from GM corn present in a quarter of them. The study was conducted six months after harvest, revealing that proteins persist in the landscape. The worry is that corn byproducts may alter the health of freshwaters. Ultimately, streams that originate in the corn belt drain into the Mississippi River, the Great Lakes, and the Gulf of Mexico. More than 85 percent of US corn crops were genetically modified to repel pests and/or resist herbicide exposure in 2009, so it's likely we're seeing the tip of a whole new iceberg here. The paper's in PNAS.
- My personal favorite, a PLoS ONE paper called "The Adaptive Function of Masturbation in a Promiscuous African Ground Squirrel." The author asked, why are these highly promiscuous squirrels wanking so much? She observed Cape ground squirrels in Namibia for 2,000 hours, wending her way through six hypotheses. Her data supported this reason:
Another possible explanation is that masturbation functions to remove potential infections transferred from a female that has previously mated—a form of genital grooming. Sexually transmitted infections (STIs) can have profound effects on fitness, even if there are no apparent symptoms. Just having an immune response to infection can affect human male fertility, including ejaculate volume, sperm concentration, sperm mobility, and sperm morphology. This hypothesis predicts that masturbation should occur on a day of oestrus, after successfully copulating, and should increase with the number of mates a female accepts. All of these predictions were supported by the masturbation data of Cape ground squirrels.
These results suggest that masturbation in this species was not a response to sperm competition nor a sexual outlet by subordinates that did not copulate. Instead masturbation could function as a form of genital grooming. Female Cape ground squirrels mate with up to 10 males in a 3-hr oestrus, and by masturbating after copulation males could reduce the chance of infection. Sexually transmitted infections can profoundly affect fertility, and their consequences for mating strategies need to be examined more fully.