Until now, it has been difficult to prove that fast-swimming sperm have an advantage when it comes to fertilizing an egg. But now a research team at Uppsala University can demonstrate that unfaithful females of the cichlid fish species influence the males’ sperm. Increased competition leads to both faster and larger sperm, and the research findings now being published in the scientific journal PNAS, Proceedings of the National Academy of Sciences, thus show that the much mythologized size factor does indeed count.
“Mom always liked you best.” The Smothers Brothers aside, chances are if you’ve got a sibling, this is something you’ve either heard or said at some point in your life. Many people feel that their parents were harder on them than on their siblings. And many are quick to blame negative outcomes in adulthood on it. But results from a Temple University study published this month in the Journals of Gerontology: Social Sciences suggest that if anything, the opposite is true.
A new study led by the U.S. Geological Survey and involving the University of Colorado at Boulder and Oregon State University as well as other research institutes indicates tree deaths in the West’s old-growth forests have more than doubled in recent decades, likely from regional warming and related drought conditions.
Although mammalian males can reproduce until late in life, evidence of hazards to offspring has emerged in human and animal models. Two papers in the February 2009 issue of the journal Biology of Reproduction provide clear, well-controlled data of deleterious effects on the offspring of aged male mice mated to females of prime reproductive age.
NOAA’s Fisheries Service has issued regulations and a letter of authorization to the U.S. Navy that includes measures to protect marine mammals while conducting Atlantic fleet active sonar training off the Atlantic coast and in the Gulf of Mexico. The regulations require the Navy to implement measures designed to protect and minimize effects to marine mammals.
Sea otters living along the central California coast risk higher exposure to disease-causing parasites as a consequence of the food they eat and where they feed.