“These kinds of problems, like sex-reversing animals skewing sex ratios, are much more dangerous than any chemical that would kill off a population of frogs,” he said. In last week’s issue of the Journal of Experimental Biology, Hayes and colleagues published a review of the possible causes of a worldwide decline in amphibian populations, concluding that atrazine and other hormone-disrupting pollutants are a likely contributor because they affect recruitment of new individuals and make amphibians more susceptible to disease. Hayes and his UC Berkeley colleagues report their results in this week’s online early edition of the journal Proceedings of the National Academy of Sciences.
Though the experiments were performed on a common laboratory frog, the African clawed frog ( Xenopus laevis), field studies indicate that atrazine, a potent endocrine disruptor, similarly affects frogs in the wild, and could possibly be one of the causes of amphibian declines around the globe, Hayes said. “In a population, the genetically male females can decrease or wipe out a population just because they skew sex ratios so badly.” “When we grow these guys up, depending on the family, we will get anywhere from 10 to 50 percent females,” Hayes said. The 10 percent or more that turn from males into females – something not known to occur under natural conditions in amphibians – can successfully mate with male frogs but, because these females are genetically male, all their offspring are male. “In an environment where they are competing with unexposed animals, they have zero chance of reproducing.”
So their fertility is as low as 10 percent in some cases, and that is only if we isolate those animals and pair them with females,” he said. “These male frogs are missing testosterone and all the things that testosterone controls, including sperm. The 75 percent that are chemically castrated are essentially “dead” because of their inability to reproduce in the wild, reports UC Berkeley’s Tyrone B. Atrazine, one of the world’s most widely used pesticides, wreaks havoc with the sex lives of adult male frogs, emasculating three-quarters of them and turning one in 10 into females, according to a new study by University of California, Berkeley, biologists.
0 kommentar(er)
