RT info:eu-repo/semantics/article
T1 Distinctive morphological features, life-cycle phases and seasonal variations in subtropical populations of Dictyota dichotoma (Dictyotales, Phaeophyceae)
A1 Afonso Carrillo, Julio
A1 Tronholm, Ana
A1 Sansón Acedo, Marta
A1 De Clerck, Olivier
A2 BotánicaEcología y Fisiología Vegetal
A2 Botánica Marina
AB Although it has been suggested that the distribution ofDictyota dichotoma is probably restricted to the European Atlantic Ocean and the Mediterranean Sea, itsoccurrence in the Canary Islands (new southernmostdistribution limit) is confirmed by nuclear ribosomalsequence data (LSU rDNA). Even though D. dichotomahas been described and illustrated prominently in earlystudies of brown algae, the species remains difficult tocharacterize due to considerable morphological plasticity. An exhaustive analysis of several quantitative characters confirms significant morphological variation bothseasonally and between life-cycle phases. The speciesmay be characterized in the Canary Islands only by thefollowing qualitative features: erect thallus attached by asingle holdfast, subdichotomous branches always ofsimilar width, straight terminal segments and smoothmargins and an entirely unilayered medulla. In the CanaryIslands, D. dichotoma is an aseasonal annual with atleast three overlapping generations in which sporophytesand gametophytes grow simultaneously. Thallus life spanseems to be less than 3 months. The species occursthroughout the year, but as cryptic microthalli in autumn.Two abundance peaks were detected with the maximumvalue in February (6.2 thalli m-2). The optimum reproductive stage (88.3% fertile specimens) occurred in winterand the maximum vegetative stage (maximum thalluslength: 18.6 cm) in summer. Sporophytes outnumberedgametophytes 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 fertilethalli were always dominant. The populations from theCanaries exhibited a temporal displacement compared tonorthern populations with the favorable period in thecoldest season (winter) and the resting period in thewarmest season (autumn).
YR 2008
FD 2008
LK http://riull.ull.es/xmlui/handle/915/27434
UL http://riull.ull.es/xmlui/handle/915/27434
LA en
DS Repositorio institucional de la Universidad de La Laguna
RD 27-dic-2024