Genetic diversity and structure of the red squat lobster (Grimothea monodon) in the Humboldt Current Ecosystem using SNP markers

The Humboldt Current Ecosystem (HCE) presents a wide variability of environmental and geographic conditions that play an important role in marine invertebrates, modulating variations not only in their behavior, physiology and morphology; but also changes in their patterns of genetic differentiation. Therefore, it is necessary to characterize genetic diversity and structure to develop management and conservation strategies in commercially important invertebrates such as the red squat lobster Grimothea monodon, which in the HCE presents two highly contrasting morphotypes and/or lifestyles (pelagic vs. benthic). The objective of the present study was to evaluate the diversity, structure, and genetic connectivity of the G. monodon population along the latitudinal gradient in the HCE using single nucleotide polymorphism (SNP) markers. Low heterozygosity (0.05 ± 0.1) and similar allelic richness among all studied populations (∼1.09) were observed. However, a slightly higher inbreeding was recorded in individuals from the Concepción population. At the level of genetic structure, using LEA and STRUCTURE, it is confirmed that G. monodon is a single population unit between the pelagic and benthic morphotypes, and that the difference observed in the discriminant analysis of principal components (DPCA) is due to the geographic distance (isolation by distance) between the extreme southern locations of the HCE (Constitución-Concepción: verified by Analysis of Molecular Variance (AMOVA) and Mantel test). The slight difference observed mainly in Concepción is due to inbreeding, however, this tends to be very low due to the high genetic flow explained by the prolonged development time of their planktonic larvae, which can positively influence an optimal recovery of their natural populations along the latitudinal gradient. This study emphasizes that the slight genetic differentiation ofG. monodon could be due only to its wide geographic distribution range, generating only intra-population variability and not inter-population variability. This is due to the high dispersal potential of their planktonic larvae, which converges as a development trait of early ontogeny for both morphotypes and/or lifestyles of this squat lobster.