Imagine for a moment that your gender was not determined at conception, but rather dictated by how much food you consumed during the early stages of your life. This is not unlike what has been described in sea lamprey, Petromyzon marinus, by U.S. Geological Survey (USGS) scientists. P. marinus is an invasive basal fish species which is a parasite and very efficient killer of bony fishes. According to the National Ocean Service (NOS) sea lamprey began their invasion of North America's Great Lakes in the 1830's and in fact a single lamprey can kill up to 40 pounds of fish a year.
From 2005 to 2007 USGS scientist tagged and tracked larval lamprey in unproductive lakes and productive streams. Sex-ratios, the ratio of males to females in a given population, were similar but rapidly began to diverge with unproductive lakes having skewed male dominated ratios and productive stream becoming female dominated.
In less productive habitats with less food they discovered 78% of the lampreys were males, while in areas with high food abundance which provide the chance for greater growth rates, populations were lower at 56% male. This is the first study suggesting growth rate directly influences sex determination. Understanding the mechanisms of sex determination in sea lamprey may provide valuable insight into the principles governing determination in other vertebrates and could also be very crucial in developing approaches to the management of this nuisance invasive species.
For the full publication please follow http://rspb.royalsocietypublishing.org/content/284/1851/20170262
Photo by Marco Colombo http://www.calosoma.it
