Epigenetic variation of lionfish populations in the Western Atlantic Ocean and Northern Gulf of Mexico
By Amy Brower, Master's Student
Introduced species pose a threat to biodiversity and can change the way a community functions in the ecosystem because the introduced species did not evolve there. Once the species establishes residence and becomes harmful to the environment it is then considered an invasive species.
Locally, two invasive species of major concern are the Red lionfish (Pterois volitans) and the Devil firefish (Pterois miles), with both commonly referred to as lionfish. Although P. volitans and P. miles are in the same genus they have separate native ranges. Pterois miles is native to the Indian ocean and the Red Sea whereas P. volitans is native to the Indo-Pacific region (see figure below).
Both of these lionfish species were introduced to the Atlantic Ocean with the first sighting off the coast of Miami, Florida in 1985. By the 1990’s lionfish started moving through the Western Atlantic easily via currents off the coast of Florida. By 2010 lionfish spread to the Gulf of Mexico and the population has since exploded. In 2015 lionfish were found to be highly invasive and found at higher densities in Pensacola, Florida when compared with other regions of their invaded range. Today, these predatory fish can be found all throughout the northern Gulf of Mexico and even all the way south of the Amazon out flow in Brazil. Genetic research has shown that only P. volitans has made it to the Gulf of Mexico, while P. miles has only spread in the western Atlantic of the invaded range.
Invasive species are thought to have generally low genetic variation resulting from population establishment of very few individuals, which usually causes inbreeding, putting the population at risk of being extirpated. Thus, the success of invasive species is misunderstood. Once an invasive species is introduced to an environment, not only do they often quickly adapt, but they also often expand their range and easily adjust to multiple environmental gradients. One potential mechanism for invasive species success can be what we call “phenotypic plasticity”, or the ability to express different phenotypes reliant on the environment. For example, lionfish, have been found in salinities as low as 5ppt, an extremely low condition, considering they are a reef species that typically live at salinities of ~35ppt. Thus, because lionfish appear to tolerate such a wide range in salinity, this phenotype is likely plastic.
One aspect of my research will be focusing on invasive populations of lionfish to see if they are utilizing phenotype plasticity to aid in successful invasion. I will be examining 5 populations: Pensacola, FL; St Pete, FL; Jacksonville FL; the Florida Keys and Andros Island, Bahamas, to compare lionfish genes of each locality to see if to what degree DNA methylation is occurring. Results will be used to determine if lionfish are utilizing phenotypic plasticity. We will also look for differences in DNA methylation among or between populations.
Stay tuned for more information about lionfish on our blog!
Photo by Meaghan Faletti