Using body geometric morphometrics to identify bluemouth, Helicolenus dactylopterus (Delaroche, 1809) populations in the Northeastern Atlantic

Abstract

In this study, landmark-based geometric morphometric methods were applied to evaluate the possible existence of different bluemouth, Helicolenus dactylopterus (Delaroche, 1809), populations in the NE Atlantic. Fish were obtained from commercial landings in Azores, Madeira, and Peniche (mainland Portugal). Samples from a research survey along the Galician coast (Spain) were also included in this study. A generalized procrustes analysis was done to remove non-shape variation. Then, the obtained shape variables were statistically adjusted to eliminate allometry and permit a comparative analysis of the samples. The discriminant analysis performed to test the homogeneity of the data set regarding sex revealed no shape differences between males and females within the four areas under study. The body shapes of bluemouth differed significantly among the four areas using Procrustes distances (P \ 0.01). In this study, a considerable morphological heterogeneity within the Azores group was observed, which could reflect a substructure of the bluemouth population within this area. According to our results, bluemouth from Galicia and Peniche seem to be relatively well separated from each other, despite both areas are relatively close geographically. Bluemouth from Madeira was well differentiated from the rest of locations and presented the highest correct classification rate in the discriminant analysis. In conclusion, morphological differences suggest that different bluemouth populations exist in the NE Atlantic, but an integrated approach, using different methods, would be needed to confirm the population structure of this species.

Identifying populations of the blue jack mackerel (Trachurus picturatus) in the Northeast Atlantic by using geometric morphometrics and otolith shape analysis

“…2.10 (Rohlf, 2006). Subsequent methodological procedures followed those of Sequeira et al (2011) and Porrini et al (2015). The tpsDig software (Rohlf, 2006) was used to acquire x and y coordinates of the landmarks previously noted, and a generalized least squares Procrustes superimposition (Rohlf, 1990) was used to adjust them.…”

“…Possible effect of area and sex on otolith normalized elliptic Fourier descriptors (NEFDs) was tested by using MANOVA. To detect possible morphometric differences in the contour shape of otoliths from the three studied areas, a canonical discriminant analysis was performed and a jackknife cross-validation procedure was carried out with IBM SPSS software to validate similarities between groups by listing the misclassification of individuals within other areas (Neves et al, 2011;Vieira et al, 2014).…”

Life history parameters as possible discriminators of bluemouth Helicolenus dactylopterus (Delaroche, 1809) populations in Portuguese waters

“…Age and growth data also support a closer relationship between Portuguese continental slope populations and those from the western Mediterranean than between mainland and Azorean samples . Recently, three other techniques (macroparasites as biological tags (Sequeira et al, 2010), body geometric morphometrics (Sequeira et al, 2011a) and otolith shape analysis (Neves et al, 2011)) throw light on the subject suggesting the separation between mainland Portugal, the Azorean and the Madeiran waters.…”

Genetic and Morphological Variation of the Forkbeard, Phycis phycis (Pisces, Phycidae): Evidence of Panmixia and Recent Population Expansion along Its Distribution Area

“…As fish morphology is particularly dependent on environmental factors during early life stages, phenotypic differentiation may indicate that most fish from each population spent their lives in separate regions [33, 70] and provide an indirect assessment of population structure. However, it does not give direct evidence of genetic isolation between populations [35, 70]. Body shape and other morphological characters have long been used to delineate populations and continue to be used successfully [30–36], based on the fact that morphological features can relate to fitness and strong selective pressures that may underlie rapid genetic divergence between groups of fish [10].…”

“…Pairwise comparisons of mean shapes of forkbeard from different areas were based on Procrustes distances, and a permutation test with 10,000 runs was used to assess the null hypothesis of no difference between samples [35]. …”