Pavithiran Amirthalingam’s research while affiliated with University of Central Florida and other places

The Indo‐Pacific lionfish, Pterois volitans, is an invasive species in the western Atlantic. Since its introduction to Florida in the early 1980s, populations have surged with lionfish now found from North Carolina to Venezuela. As their range expands, these generalist predators threaten native fauna, and while they are primarily a marine species, their tolerance for low salinity conditions may allow them to expand into sensitive estuarine habitats undetected. Traditional approaches for tracking invasive species such as direct observation or trapping are impractical over large spatial scales, making environmental DNA (eDNA) an attractive alternative. Molecular assays, such as those employing quantitative polymerase chain reaction (qPCR), amplify low copy number DNA fragments in environmental samples and are increasingly employed as a complement to traditional methods for the detection of invasive species. Currently, there is one published PCR assay for the detection of lionfish eDNA. However, the specificity of this assay is unverified, and the critical performance parameters limit of detection (LOD) and limit of quantification (LOQ) have not been established. Here we evaluate the efficacy of this assay and show that it is likely to result in false negatives in the western Atlantic. As an alternative, we developed a new TaqMan probe‐based qPCR assay that is species‐specific for P. volitans and highly sensitive with a LOD of 12 copies per reaction and a LOQ of 598 copies per reaction. While our assay does not amplify the closely related P. miles, which was also introduced in the western Atlantic, the low prevalence of this species in the invasive population means our assay is effective for most monitoring purposes. We conclude that our assay is a robust method for the detection of lionfish and can be employed in any habitat, offering new opportunities for controlling the spread of invasive lionfish.

The Indo-Pacific lionfish Pterois volitans is an invasive species in the western Atlantic. Since their introduction in Florida in the early 1980’s, populations have exploded with lionfish now found from North Carolina to Venezuela. As their range expands, these generalist predators threaten native fauna, and while they are primarily a marine species, their tolerance for low salinity conditions may allow them to expand into sensitive estuarine habitats undetected. Traditional approaches for tracking invasive species such as direct observation or trapping are impractical across large spatial scales making environmental DNA (eDNA) an attractive alternative. Currently, there is only one published PCR assay for the detection of lionfish eDNA. However, the specificity of this assay is unverified, and the critical performance parameters limits of detection (LOD) and limits of quantification (LOQ) have not been established. Here we evaluate the specificity of the currently available lionfish assay, determined that it is not species-specific, and is likely to provide false negatives in the western Atlantic. As an alternative, we developed a new qPCR TaqMan probe-based assay that is species-specific for P. volitans and highly sensitive with a LOD of 12 copies per reaction and a LOQ of 598 copies per reaction. While our assay does not amplify the closely related P. miles , which is also invasive in the western Atlantic, the low prevalence of this species in the invasive population means our assay is effective for most monitoring purposes.

Understanding the process of speciation is a primary goal of evolutionary biology, yet the question of whether speciation can reach completion in the presence of gene flow is still controversial. For more than 50 years, the cichlids of Africa, and more recently those in South and Central America, have served as model systems for the study of speciation in nature. Cichlids are distinguished by their enormous species richness, diversity of behavioral and trophic adaptations, and their rapid rate of divergence. In both Africa and South and Central America, the repeated interaction of geology, new founder events, and adaptive evolution has created a series of natural experiments with speciation occurring both within and between waterbodies of differing ages. In the “From the Cover” manuscript, Raffini, Schneider, Franchini, Kautt, & Meyer (2020) move beyond the question of which mechanisms drive speciation, and instead show that divergent morphologies and physiologies translate into adaptive traits. They investigate differences in physiology and gene expression profiles in a benthic/limnetic species pair of Midas cichlid fish in a 24k year old Nicaraguan crater lake. While recently diverged, these two species demonstrate significant ecological but limited genetic differentiation. The authors find that the distinct morphotypes translate into relevant differences in swimming performance and metabolic rates that correspond with differential gene expression profiles. Hence, the authors take an integrative approach examining the impacts of morphological differences on performance and niche partitioning: an approach that can advance our understanding of the drivers of morphological and physiological divergence during speciation.