While Al Gore's film, An Inconvenient Truth, has generated greater awareness of global warming, most people remain unaware of the more rapid warming that has occurred within major cities. In fact, large cities can be more than 10 degrees hotter than their surroundings. These metropolitan hot spots, which scientists refer to as urban heat islands, can stress the animals and plants that make their home alongside humans. Until recently, biologists had focused so much on the effects of global climate change, that they had overlooked the effects of urban warming.
Why do some birds fly thousands of miles back and forth between breeding and non-breeding areas every year whereas others never travel at all? One textbook explanation suggests that eating fruit or living in nonforested environments were the precursors needed to evolve migratory behavior. Not so, report ecologists W. Alice Boyle and Courtney J. Conway of the University of Arizona, Tucson, in the March issue of the American Naturalist.
Any dieter can tell you: Body weight is a function of how much food you eat and how much energy you use. The trick to maintaining a healthy weight lies in regulating the balance. Now new research from Rockefeller University suggests that brain cell receptors linked to sex hormones may play a role in the process by which we maintain that balance. The findings show that metabolic syndrome, a cluster of conditions that includes obesity, insulin resistance and reduced physical activity, occurs in female mice when estrogen signaling in specific areas of the brain is shut down.
Using a variety of new approaches, scientists at Scripps Institution of Oceanography at UC San Diego are forging a new understanding of the largest mammals on Earth. In one recently published study on blue whales, Scripps researchers used a combination of techniques to show for the first time that blue whale calls can be tied to specific behavior and gender classifications. In a separate study, researchers used recordings of blue whale songs to determine the animal's population distributions worldwide.
Frogs are more sensitive to hormone-disturbing environmental pollutants than was previously thought. Male tadpoles that swim in water with relevant levels of such substances become females, according to a new study from Uppsala University that will be published in the scientific journal Environmental Toxicology and Chemistry (ET&C) in May.
Promiscuity is common among female rodents, leading to competition between the sperm of rival males over who fertilizes the eggs. It now seems that possessing a longer penis may give males an advantage in this competition, according to new research to be published in the March issue of The American Naturalist.
The sugar-containing nectar secreted by plants and consumed by pollinators shares a number of similarities to fitness drinks, including ingredients such as amino acids and vitamins. In addition to these components, nectar can also contain secondary metabolites such as the alkaloid nicotine and other toxic compounds.