Geographic variation in Loligo forbesi in the Northeast Atlantic Ocean: analysis of morphometric data and tests of causal hypotheses

Pierce, Graham J.; Thorpe, Roger S.; Hastie, Lee C.; Brierley, Andrew S.; Guerra, Ángel; Boyle, Peter Robin; Jamieson, Robyn E.; Avila, Piret

doi:10.1007/bf00354316

Cited by 37 publications

(22 citation statements)

References 19 publications

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“…Moreover, body coloration, which was previously used as one of the identifying characters of these two species, usually depends on the habitat. The present study has uncovered some morphological (i.e., morphometric and meristic) distinctions between the two closely related archer fishes, using multivariate techniques as reported for other marine vertebrates and invertebrates (Fridriksson, 1958;Boetius, 1980;Pierce et al, 1994a;1994b;Tudela, 1999;Bolles and Begg, 2000). This study demonstrates that T. chatareus and T. jaculatrix from Matang coastal waters were different from one another in both morphometric and meristic traits.…”

Section: Discussionmentioning

confidence: 68%

Morphometric and meristic variation in two congeneric archer fishes Toxotes chatareus (Hamilton 1822) and Toxotes jaculatrix (Pallas 1767) inhabiting Malaysian coastal waters

Das

Bakar

Temple

et al. 2010

J. Zhejiang Univ. Sci. B

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Abstract:A simple yet useful criterion based on external markings and/or number of dorsal spines is currently used to differentiate two congeneric archer fish species Toxotes chatareus and Toxotes jaculatrix. Here we investigate other morphometric and meristic characters that can also be used to differentiate these two species. Principal component and/or discriminant functions revealed that meristic characters were highly correlated with pectoral fin ray count, number of lateral line scales, as well as number of anal fin rays. The results indicate that T. chatareus can be distinguished from T. jaculatrix by having a greater number of lateral line scales, a lower number of pectoral fin rays, and a higher number of anal fin rays. In contrast, morphometric discriminant analyses gave relatively low distinction: 76.1% of fish were ascribed to the correct species cluster. The observed morphometric differences came from the dorsal and anal spines lengths, with T. chatareus having shorter dorsal and longer anal spines than T. jaculatrix. Overall, meristic traits were more useful than morphometrics in differentiating the two species; nevertheless, meristics and morphometrics together provide information about the morphological differentiation between these two closely related archer fishes.

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Section: Discussionmentioning

confidence: 68%

Morphometric and meristic variation in two congeneric archer fishes Toxotes chatareus (Hamilton 1822) and Toxotes jaculatrix (Pallas 1767) inhabiting Malaysian coastal waters

Das

Bakar

Temple

et al. 2010

J. Zhejiang Univ. Sci. B

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“…Thus the data standardization used in this study could be one of the reasons behind the difference in the results obtained in this study and those of previous studies. Simultaneous sampling was recommended for reducing the size effect in morphormetric studies (Pierce et al 1994, Vega et al 2002. Biases in sampling might result in a lower intraspecific morphormetric variation than the true variation existing in nature, and thus the error rate in the discriminating process would be underestimated (Yatsu et al 1997), in particular for widely distributed and rapidly growing species like cephalopods.…”

Section: Discussionmentioning

confidence: 99%

Species identification of <i>Ommastrephes bartramii, Dosidicus gigas, Sthenoteuthis oualaniensis</i> and <i>Illex argentinus</i> (Ommastrephidae) using beak morphological variables

Chen¹,

Lu²,

Liu³

et al. 2012

Sci. Mar.

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SUMMARY: Four oceanic squid species, Ommastrephes bartramii, Dosidicus gigas, Sthenoteuthis oualaniensis and Illex argentinus, not only support important commercial fisheries, but also play a vital role in their marine ecosystems. It is therefore important to identify them in the analyses of their predators' stomach contents as this can yield critical information on the trophic dynamics of ecosystems. Hard beaks of the four species frequently found in their predators' stomachs can be used to identify them. In this study, to remove the effect of size differences among individuals, measurements of upper and lower beaks were standardized with an allometric model. A discriminant analysis was carried out to compare morphological differences among the four species and between the sexes for each species. The upper rostral width and upper rostral length showed the greatest interspecific variation in the beak morphological variables of the four Ommastrephidae. The linear discriminant functions of beak morphological variables were developed for the four Ommastraphidae, which resulted in a rate of correct species classification of over 97%. Sexual dimorphism was also found in the beak morphology of O. bartramii and I. argentinus. This study suggests that morphological variables can be used to reliably classify Ommastrephidae at genus level, which can help identify the specie in the stomachs of cephalopod predators. This helps to improve the understanding of the role cephalopods play in their marine ecosystems. Ommastrephes bartramii, Dosidicus gigas, Sthenoteuthis oualaniensis e Illex argentinus, sometidas a una importante presión pesquera, juegan un papel significativo dentro de los ecosistemas marinos a los que pertenecen. Al ser los picos de estas especies resistentes, las medidas de diversos aspectos de su morfología pueden servir para identificarlas en análisis de contenidos estomacales de sus depredadores. Ello permite obtener una información crucial sobre la dinámica trófica de los ecosistemas. En el presente estudio, las medidas realizadas en los picos superior e inferior de los Ommastrephidae se han normalizado mediante un modelo de crecimiento alométrico, para evitar la influencia del efecto tamaño de los individuos. A continuación, mediante un análisis discriminante, se han estudiado las diferencias morfológicas entre las cuatro especies, así como entre machos y hembras. Las medidas que presentaban mayores variaciones eran la anchura y longitud del rostro superior. Mediante funciones discriminantes lineales de las medidas morfológicas normalizadas de sus picos, se han conseguido clasificar las cuatro especies de Ommastraphidae, con una fiabilidad superior al 97%. Asimismo, a través de sus medidas morfológicas, se ha encontrado un claro dimorfismo sexual en los picos de O. bartramii e I. argentinus. El presente estudio sugiere que las medidas morfológicas pueden ser útiles para clasificar correctamente los Ommastrephidae a nivel de Scientia Marina 76(3) September 2012, 473-481, Barcelona (Spain) Keywords

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“…However, an important depth pattern of variation seems to occur between slope and shelf samples, confirming the existence of different groups (the IiP-slope sample was 100% identified, whereas a few shelf specimens from Canada were misclassified as IiNY-shelf from the USA). Similarly, morphometric analysis of Loligo squids according to beak and body characters has indicated a pattern of variation between offshore waters (Azores Islands) and those on the continental shelf (Pierce et al 1994). Further I. illecebrosus investigations on various hypothetical geographical groups along the north-western Atlantic should be carried out.…”

Section: Illex Illecebrosusmentioning

confidence: 97%

“…Multivariate discriminant analysis on Loligo spp. has indicated patterns of variation and allowed diagnosis (Augustyn and Grant 1988;Boyle and Ngoile 1993;Pierce et al 1994;Pineda et al 2000;Vega et al 2002). However, no single discriminant analysis, by either body or beak characters, has been ventured for the diagnosis of Illex species, and attempts at geographical identification have also been limited (O'Dor and Lipinski 1998;Roper and Mangold 1998;.…”

Section: Introductionmentioning

confidence: 99%

Identification of Illex coindetii , I . illecebrosus and I . argentinus (Cephalopoda: Ommastrephidae) throughout the Atlantic Ocean; by body and beak characters

2002

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Shortfinned squid species of the genus Illex support commercial fisheries throughout the Atlantic Ocean and Mediterranean Sea. Previous identification of interspecific and intraspecific populations by morphological and size-at-maturity studies have not provided conclusive results. We analysed morphometric body and beak variables (24 characters) in three species of the genus (I. coindetii, I. illecebrosus and I. argentinus), using a geographic and seasonal series of 33 populations for 1,500 specimens of I. coindetii, I. illecebrosus and I. argentinus. Residuals of the regression between each morphometric body and beak variable and mantle length were used as input in a stepwise discriminant analysis. Species discrimination by body and hectocotylus characters required at least eight variables and resulted in high correct-classification percentages for I. coindetii and I. argentinus (75% and 90%, respectively), whereas the best identification resulted from beak characters (83% correctly classified

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Geographic variation in Loligo forbesi in the Northeast Atlantic Ocean: analysis of morphometric data and tests of causal hypotheses

Cited by 37 publications

References 19 publications

Morphometric and meristic variation in two congeneric archer fishes Toxotes chatareus (Hamilton 1822) and Toxotes jaculatrix (Pallas 1767) inhabiting Malaysian coastal waters

Morphometric and meristic variation in two congeneric archer fishes Toxotes chatareus (Hamilton 1822) and Toxotes jaculatrix (Pallas 1767) inhabiting Malaysian coastal waters

Species identification of <i>Ommastrephes bartramii, Dosidicus gigas, Sthenoteuthis oualaniensis</i> and <i>Illex argentinus</i> (Ommastrephidae) using beak morphological variables

Identification of Illex coindetii , I . illecebrosus and I . argentinus (Cephalopoda: Ommastrephidae) throughout the Atlantic Ocean; by body and beak characters

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