Distinctive morphological features, life-cycle phases and seasonal variations in subtropical populations of Dictyota dichotoma (Dictyotales, Phaeophyceae)
Although it has been suggested that the distribution of Dictyota dichotoma is probably restricted to the European Atlantic Ocean and the Mediterranean Sea, its occurrence in the Canary Islands (new southernmost distribution limit) is confirmed by nuclear ribosomal sequence data (LSU rDNA). Even thou...
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ftunivgent:oai:archive.ugent.be:746115 2023-06-11T04:14:58+02:00 Distinctive morphological features, life-cycle phases and seasonal variations in subtropical populations of Dictyota dichotoma (Dictyotales, Phaeophyceae) Tronholm, Ana Sanson, Marta Afonso-Carrillo, Julio De Clerck, Olivier 2008 https://biblio.ugent.be/publication/746115 http://hdl.handle.net/1854/LU-746115 https://doi.org/10.1515/BOT.2008.017 eng eng https://biblio.ugent.be/publication/746115 http://hdl.handle.net/1854/LU-746115 http://dx.doi.org/10.1515/BOT.2008.017 BOTANICA MARINA ISSN: 0006-8055 morphology nuclear ribosomal sequence data (LSU rDNA) Dictyota dichotoma Canary Islands COAST ALGAE ISLANDS PATTERNS AUSTRALIA phenology PERIODICITY NORTH-ATLANTIC REPRODUCTION seasonal variation journalArticle info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2008 ftunivgent https://doi.org/10.1515/BOT.2008.017 2023-05-10T22:24:28Z Although it has been suggested that the distribution of Dictyota dichotoma is probably restricted to the European Atlantic Ocean and the Mediterranean Sea, its occurrence in the Canary Islands (new southernmost distribution limit) is confirmed by nuclear ribosomal sequence data (LSU rDNA). Even though D. dichotoma has been described and illustrated prominently in early studies of brown algae, the species remains difficult to characterize due to considerable morphological plasticity. An exhaustive analysis of several quantitative characters confirms significant morphological variation both seasonally and between life-cycle phases. The species may be characterized in the Canary Islands only by the following qualitative features: erect thallus attached by a single holdfast, subdichotomous branches always of similar width, straight terminal segments and smooth margins and an entirely unilayered medulla. In the Canary Islands, D. dichotoma is an aseasonal annual with at least three overlapping generations in which sporophytes and gametophytes grow simultaneously. Thallus life span seems to be less than 3 months. The species occurs throughout the year, but as cryptic microthalli in autumn. Two abundance peaks were detected with the maximum value in February (6.2 thalli m(-2)). The optimum reproductive stage (88.3% fertile specimens) occurred in winter and the maximum vegetative stage (maximum thallus length: 18.6 cm) in summer. Sporophytes outnumbered gametophytes throughout the year, with ratios decreasing from 13.2 +/- 1.1 in winter to 1.9 +/- 0.2 in summer. Gametophytes made up to 25% of the population and fertile thalli were always dominant. The populations from the Canaries exhibited a temporal displacement compared to northern populations with the favorable period in the coldest season (winter) and the resting period in the warmest season (autumn). Article in Journal/Newspaper North Atlantic Ghent University Academic Bibliography Holdfast ENVELOPE(-66.590,-66.590,-66.803,-66.803) Botanica Marina 51 2 |
institution |
Open Polar |
collection |
Ghent University Academic Bibliography |
op_collection_id |
ftunivgent |
language |
English |
topic |
morphology nuclear ribosomal sequence data (LSU rDNA) Dictyota dichotoma Canary Islands COAST ALGAE ISLANDS PATTERNS AUSTRALIA phenology PERIODICITY NORTH-ATLANTIC REPRODUCTION seasonal variation |
spellingShingle |
morphology nuclear ribosomal sequence data (LSU rDNA) Dictyota dichotoma Canary Islands COAST ALGAE ISLANDS PATTERNS AUSTRALIA phenology PERIODICITY NORTH-ATLANTIC REPRODUCTION seasonal variation Tronholm, Ana Sanson, Marta Afonso-Carrillo, Julio De Clerck, Olivier Distinctive morphological features, life-cycle phases and seasonal variations in subtropical populations of Dictyota dichotoma (Dictyotales, Phaeophyceae) |
topic_facet |
morphology nuclear ribosomal sequence data (LSU rDNA) Dictyota dichotoma Canary Islands COAST ALGAE ISLANDS PATTERNS AUSTRALIA phenology PERIODICITY NORTH-ATLANTIC REPRODUCTION seasonal variation |
description |
Although it has been suggested that the distribution of Dictyota dichotoma is probably restricted to the European Atlantic Ocean and the Mediterranean Sea, its occurrence in the Canary Islands (new southernmost distribution limit) is confirmed by nuclear ribosomal sequence data (LSU rDNA). Even though D. dichotoma has been described and illustrated prominently in early studies of brown algae, the species remains difficult to characterize due to considerable morphological plasticity. An exhaustive analysis of several quantitative characters confirms significant morphological variation both seasonally and between life-cycle phases. The species may be characterized in the Canary Islands only by the following qualitative features: erect thallus attached by a single holdfast, subdichotomous branches always of similar width, straight terminal segments and smooth margins and an entirely unilayered medulla. In the Canary Islands, D. dichotoma is an aseasonal annual with at least three overlapping generations in which sporophytes and gametophytes grow simultaneously. Thallus life span seems to be less than 3 months. The species occurs throughout the year, but as cryptic microthalli in autumn. Two abundance peaks were detected with the maximum value in February (6.2 thalli m(-2)). The optimum reproductive stage (88.3% fertile specimens) occurred in winter and the maximum vegetative stage (maximum thallus length: 18.6 cm) in summer. Sporophytes outnumbered gametophytes throughout the year, with ratios decreasing from 13.2 +/- 1.1 in winter to 1.9 +/- 0.2 in summer. Gametophytes made up to 25% of the population and fertile thalli were always dominant. The populations from the Canaries exhibited a temporal displacement compared to northern populations with the favorable period in the coldest season (winter) and the resting period in the warmest season (autumn). |
format |
Article in Journal/Newspaper |
author |
Tronholm, Ana Sanson, Marta Afonso-Carrillo, Julio De Clerck, Olivier |
author_facet |
Tronholm, Ana Sanson, Marta Afonso-Carrillo, Julio De Clerck, Olivier |
author_sort |
Tronholm, Ana |
title |
Distinctive morphological features, life-cycle phases and seasonal variations in subtropical populations of Dictyota dichotoma (Dictyotales, Phaeophyceae) |
title_short |
Distinctive morphological features, life-cycle phases and seasonal variations in subtropical populations of Dictyota dichotoma (Dictyotales, Phaeophyceae) |
title_full |
Distinctive morphological features, life-cycle phases and seasonal variations in subtropical populations of Dictyota dichotoma (Dictyotales, Phaeophyceae) |
title_fullStr |
Distinctive morphological features, life-cycle phases and seasonal variations in subtropical populations of Dictyota dichotoma (Dictyotales, Phaeophyceae) |
title_full_unstemmed |
Distinctive morphological features, life-cycle phases and seasonal variations in subtropical populations of Dictyota dichotoma (Dictyotales, Phaeophyceae) |
title_sort |
distinctive morphological features, life-cycle phases and seasonal variations in subtropical populations of dictyota dichotoma (dictyotales, phaeophyceae) |
publishDate |
2008 |
url |
https://biblio.ugent.be/publication/746115 http://hdl.handle.net/1854/LU-746115 https://doi.org/10.1515/BOT.2008.017 |
long_lat |
ENVELOPE(-66.590,-66.590,-66.803,-66.803) |
geographic |
Holdfast |
geographic_facet |
Holdfast |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
BOTANICA MARINA ISSN: 0006-8055 |
op_relation |
https://biblio.ugent.be/publication/746115 http://hdl.handle.net/1854/LU-746115 http://dx.doi.org/10.1515/BOT.2008.017 |
op_doi |
https://doi.org/10.1515/BOT.2008.017 |
container_title |
Botanica Marina |
container_volume |
51 |
container_issue |
2 |
_version_ |
1768371384937873408 |