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The rediscovery of Caulerpa prolifera in Ria Formosa, Portugal, 60 years after the previous record

Publication . Cunha, A. H.; E, Varela-Álvarez; Paulo, D. S.; Sousa, Inês; Serrão, Ester

The westernmost occurrence of Caulerpa prolifera on the Atlantic European coast has been accepted in recent decades, to be Huelva province, southern Spain. In April 2011, this species was found in Ria Formosa, southern Portugal, extending its westernmost limit along the Iberian Peninsula coastline. In the course of research into this species it was discovered that this alga had been found in Ria Formosa in the 19th century by the naturalist Welwitsch and subsequently in the 1930s by others but it was never found in the many field studies conducted in Ria Formosa during the past few decades. The species had therefore either become extinct in the area or persisted as a cryptic undetected stage. In order to investigate the source of colonization and to verify the genetic identity, a partial cpDNA region (tufA gene) was sequenced. Comparisons of nucleotide similarity in sequences from the Ria Formosa and from populations of the Atlantic and Mediterranean confirmed the Caulerpa prolifera identification and gave clues about a possible origin of this population as deriving from expansion of a Mediterranean source rather than one from the western Atlantic.

2013Journal article

Open Access

Mediterranean Species of Caulerpa Are Polyploid with Smaller Genomes in the Invasive Ones

Publication . E, Varela-Álvarez; Gómez Garreta, A.; Rull Lluch, J.; Salvador Soler, N.; Serrão, Ester; Siguán, M. A. R.

Caulerpa species are marine green algae, which often act as invasive species with rapid clonal proliferation when growing outside their native biogeographical borders. Despite many publications on the genetics and ecology of Caulerpa species, their life history and ploidy levels are still to be resolved and are the subject of large controversy. While some authors claimed that the thallus found in nature has a haplodiplobiontic life cycle with heteromorphic alternation of generations, other authors claimed a diploid or haploid life cycle with only one generation involved. DAPI-staining with image analysis and microspectrophotometry were used to estimate relative nuclear DNA contents in three species of Caulerpa from the Mediterranean, at individual, population and species levels. Results show that ploidy levels and genome size vary in these three Caulerpa species, with a reduction in genome size for the invasive ones. Caulerpa species in the Mediterranean are polyploids in different life history phases; all sampled C. taxifolia and C. racemosa var. cylindracea were in haplophasic phase, but in C. prolifera, the native species, individuals were found in both diplophasic and haplophasic phases. Different levels of endopolyploidy were found in both C. prolifera and C. racemosa var. cylindracea. Life history is elucidated for the Mediterranean C. prolifera and it is hypothesized that haplophasic dominance in C. racemosa var. cylindracea and C. taxifolia is a beneficial trait for their invasive strategies.

2012-10-22Journal article

Open Access