Assessment of spatial and temporal variability of three Sargassum species (Fucales, Phaeophyta) from KwaZulu-Natal, South Africa

Gillespie, R. D.; Critchley, Alan T.

doi:10.1111/j.1440-1835.2001.tb00254.x

Cited by 4 publications

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“…Use of numerical methods (by means of comparisons of coefficient of variation [CV]) on morphology to distinguish closely related taxa is one of the proposed approaches to ascertain boundaries among species (Kilar 1992, Kilar et al. 1992, Gillespie and Critchley 2001). Ordination methods in multivariate analysis were successfully applied to delineate plant species in terms of morphology (Pinheiro de Carvalho et al.…”

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MORPHOLOGICAL AND GENETIC VARIATION IN THE POPULATIONS OF SARGASSUM HEMIPHYLLUM (PHAEOPHYCEAE) IN THE NORTHWESTERN PACIFIC¹

Cheang

Chu

Ang

2008

Journal of Phycology

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Difficulty in species identification of Sargassum (Sargassaceae, Fucales) is partly attributed to the high polymorphism among its individuals and populations. This study aimed at assessing morphological and genetic variations in two varieties, var. hemiphyllum J. Agardh and var. chinense J. Agardh, of Sargassum hemiphyllum (Turner) C. Agardh, a widely distributed species in the northwestern Pacific. We investigated 26 measurable, five numerical, and 33 categorical morphological parameters associated with different branching levels of specimens from each of six localities within its distribution range using cluster analysis (CA) and principal coordinate analysis (PCoA). Leaf size of the primary and secondary branching levels and the vesicle size of the secondary branches of the specimens examined were determined to be the most important morphological parameters that were significantly different among populations. Change in leaf and vesicle length of individuals among the six populations followed a latitudinal gradient, with smaller leaves and vesicles associated with northern populations and larger ones in the southern populations. The possible influence of the gradual change in sea surface temperatures (SSTs) along this gradient in the northwestern Pacific on leaf and vesicle morphologies of this species was suggested. PCR-RFLP analysis of the RUBISCO spacer in the chloroplast genome revealed two distinct and highly homogenous clades, a China clade and a Japan-Korea clade, which corresponded to var. chinense and var. hemiphyllum, respectively. The formation of refugia along the "Paleo-coast" in the East China Sea during glacial periods is suggested to have led to the vicariance of ancestral populations of S. hemiphyllum and thus to have promoted genetic differentiation. The massive freshwater outflow of the Yellow and Yangtze rivers may continue to act as a barrier, prolonging the allopatric distribution of the two varieties.

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MORPHOLOGICAL AND GENETIC VARIATION IN THE POPULATIONS OF SARGASSUM HEMIPHYLLUM (PHAEOPHYCEAE) IN THE NORTHWESTERN PACIFIC¹

Cheang

Chu

Ang

2008

Journal of Phycology

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“…These taxonomic ambiguities are mainly linked to morphological key characters, which are known to often exhibit important intrataxon phenotypic variations even within populations or depending on habitat diversity and seasons (De Wreede 1976, Magruder 1988, Kilar et al. 1992, Trono 1992, Gillespie and Critchley 2001). In addition, numerous species have been described from old and fragmentary material not following the existing phenotypic plasticity (Mattio et al.…”

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TAXONOMIC REVISION AND GEOGRAPHIC DISTRIBUTION OF THE SUBGENUS SARGASSUM (FUCALES, PHAEOPHYCEAE) IN THE WESTERN AND CENTRAL PACIFIC ISLANDS BASED ON MORPHOLOGICAL AND MOLECULAR ANALYSES¹

Mattio¹,

Payri²,

Verlaque³

2009

Journal of Phycology

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The species diversity of the subgenus Sargassum was reassessed for the southwestern Pacific with special focus on the Solomon Islands, Vanuatu, Fiji, and Wallis. Five taxa were recognized on the basis of morphological characters and corroborated by DNA analyses of the nuclear internal transcribed spacer 2 (ITS-2), chloroplastic partial rbcLS-operon, and mitochondrial cox3. Based on the study of diagnoses and type specimens, four taxa were identified to S. polyphyllum J. Agardh, S. polycystum C. Agardh, S. aquifolium (Turner) C. Agardh, and S. ilicifolium (Turner) C. Agardh, while one taxon remained unidentified. We present a key for identification that includes detailed descriptions of the species and illustrations of their morphological variability. In light of our findings, we propose to consider several new synonymies for S. aquifolium, S. ilicifolium, S. polycystum, and S. polyphyllum. We also include a review of Sargassum floras from Samoa, Tonga, and Nauru and discuss species distribution in the southwest and central Pacific. Finally, DNA phylogenies pointed to the polyphyly of section Acanthocarpicae and underlined the need for a new section in which to place S. polycystum, S. herporhizum Setch. et N. L. Gardner, and S. stolonifolium Phang et T. Yoshida. The new section Polycystae Mattio et Payri is described to fit species of the subgenus Sargassum with stolon-like branches.

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“…1985;Kilar &. Hanisak, 1988;Núñez-López & Casas-Valdéz, 1996;Gillespie & Critchley, 2001 (Paula, 1978(Paula, , 1984(Paula, , 1988Kilar et al 1992b;Ang, 1985;Ang & Trono, 1987 (Kilar et al 1992b). …”

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Inferências filogenéticas na ordem Fucales (Phaeophyceae), com ênfase no gênero Sargassum C. Agardh do Atlântico Sul

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Assessment of spatial and temporal variability of three Sargassum species (Fucales, Phaeophyta) from KwaZulu-Natal, South Africa

Cited by 4 publications

References 2 publications

MORPHOLOGICAL AND GENETIC VARIATION IN THE POPULATIONS OF SARGASSUM HEMIPHYLLUM (PHAEOPHYCEAE) IN THE NORTHWESTERN PACIFIC¹

MORPHOLOGICAL AND GENETIC VARIATION IN THE POPULATIONS OF SARGASSUM HEMIPHYLLUM (PHAEOPHYCEAE) IN THE NORTHWESTERN PACIFIC¹

TAXONOMIC REVISION AND GEOGRAPHIC DISTRIBUTION OF THE SUBGENUS SARGASSUM (FUCALES, PHAEOPHYCEAE) IN THE WESTERN AND CENTRAL PACIFIC ISLANDS BASED ON MORPHOLOGICAL AND MOLECULAR ANALYSES¹

Inferências filogenéticas na ordem Fucales (Phaeophyceae), com ênfase no gênero Sargassum C. Agardh do Atlântico Sul

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Assessment of spatial and temporal variability of three Sargassum species (Fucales, Phaeophyta) from KwaZulu-Natal, South Africa

Cited by 4 publications

References 2 publications

MORPHOLOGICAL AND GENETIC VARIATION IN THE POPULATIONS OF SARGASSUM HEMIPHYLLUM (PHAEOPHYCEAE) IN THE NORTHWESTERN PACIFIC1

MORPHOLOGICAL AND GENETIC VARIATION IN THE POPULATIONS OF SARGASSUM HEMIPHYLLUM (PHAEOPHYCEAE) IN THE NORTHWESTERN PACIFIC1

TAXONOMIC REVISION AND GEOGRAPHIC DISTRIBUTION OF THE SUBGENUS SARGASSUM (FUCALES, PHAEOPHYCEAE) IN THE WESTERN AND CENTRAL PACIFIC ISLANDS BASED ON MORPHOLOGICAL AND MOLECULAR ANALYSES1

Inferências filogenéticas na ordem Fucales (Phaeophyceae), com ênfase no gênero Sargassum C. Agardh do Atlântico Sul

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MORPHOLOGICAL AND GENETIC VARIATION IN THE POPULATIONS OF SARGASSUM HEMIPHYLLUM (PHAEOPHYCEAE) IN THE NORTHWESTERN PACIFIC¹

MORPHOLOGICAL AND GENETIC VARIATION IN THE POPULATIONS OF SARGASSUM HEMIPHYLLUM (PHAEOPHYCEAE) IN THE NORTHWESTERN PACIFIC¹

TAXONOMIC REVISION AND GEOGRAPHIC DISTRIBUTION OF THE SUBGENUS SARGASSUM (FUCALES, PHAEOPHYCEAE) IN THE WESTERN AND CENTRAL PACIFIC ISLANDS BASED ON MORPHOLOGICAL AND MOLECULAR ANALYSES¹