March 31, 2017 Volume 23, Number 13 |
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New Research Suggests that Access to Food Determines Lamprey Sex | |
Growth spurts may determine a lamprey's sex Sex-shifting fish: Growth rate could determine sea lamprey sex Sex of Fish Determined by Access to Food, Surprised Researchers Say Parasitic fish offer evolutionary insights USGS: Sea Lamprey (Petromyzon marinus) FactSheet Sex Determination: Why so Many Ways of Doing It? The Lamprey, a parasitic, jawless fish, is perhaps best known as an invasive species in the Great Lakes region of North America. Another distinctive fact about the lamprey, however, is that a decisive majority of their adult population is male. Biologists have long wondered what accounts for this lopsided sex ratio. This past week, a team of researchers from the US Geological Survey and Michigan State University, led by biologist Nick Johnson, published a paper in Proceedings of the Royal Society B advancing a new hypothesis. Lamprey sex may be determined by how quickly they grow as larvae, a rate that, in turn, is influenced by their environment. Johnson and his team tagged and released hundreds of larval lamprey into a variety of streams in the Great Lakes region of the U.S. The result? An overwhelming 78% of lampreys that developed in nutrient poor areas were male, compared to 56% that grew up in nutrient rich streams. This suggests that when larvae are able to consume more nutrients and develop more quickly, they are also more likely to develop eggs. Notably, this discovery came as a surprise to the research team. As Johnson explains, "Remarkably, we didn't set out to study sex determination in sea lampreys - we were planning to study environmental effects on growth rates only. We were startled when we discovered that these data may also reveal how sex is determined because mechanisms of sex determination in lamprey are considered a holy grail for researchers." [MMB] The first three articles, from Nature, Phys Org, and the American Council of Health and Science, provide an overview of this research. This new study on lamprey sex development is not the only significant research about the species to be recently published. Earlier this month, a team of scientists at the California Institute of Technology studied gut neurons in lampreys, uncovering clues about how neurons evolved in early vertebrate species. Readers can learn about the Caltech study via the fourth link. Moving along, those looking to learn more about the sea lamprey may want to check out the United States Geological Survey's (USGS) page dedicated to the species, which includes basic facts and links to additional resources. Finally, the last link takes readers to a 2014 article in PLOS that explores the diversity of sex determination across species. |