Chapter 6. Primary Production, Cycling of Nutrients, Surface Layer and Plankton.

RADIALES (IEO)Versión del edito

Halophila decipiens, An Unreported Seagrass From The Philippines

Volume: 98Start Page: 232End Page: 23

Morphology, vegetative and reproductive development of the red alga <i>Portieria hornemannii</i> (Gigartinales: Rhizophyllidaceae)

Earlier descriptions of the Indo-Pacific red alga Portieria hornemannii lacked detailed information on its vegetative and reproductive development and morphology. An in-depth treatment is presented on the development of the uniaxial thallus and the formation of male, female and tetrasporangial nemathecia. Post fertilization events and carposporophyte development is described, confirming Kylin's presumption on the development of connecting filaments between the carpogonium and the auxiliary cell following fertilization. Phylogenetic analysis using chloroplast encoded rbcL and nuclear ribosomal LSU gene sequences, including members of Rhizophyllidaceae and their close relatives suggests a monophyletic family. Contarinia is resolved as the sister taxon of a clade uniting Nesophila, Ochtodes and Portieria. The relationships among the latter genera remain largely unresolved

<i>Chaetomorpha philippinensis</i> (Cladophorales, Chlorophyta), a new marine microfilamentous green alga from tropical waters

A new marine microfilamentous green alga, Chaetomorpha philippinensis Leliaert sp. nov., is described as an epiphyte on Chaetomorpha vieillardii from shallow subtidal habitats in the Philippines. Phylogenetic analyses of large subunit rDNA and rDNA internal transcribed spacer (ITS) sequences show that the new tropical species is sister to the cold-water Chaetomorpha norvegica, from which it is genetically clearly distinct but morphologically almost indistinguishable. Chaetomorpha philippinensis is characterized by minute, straight or curved, unbranched, erect filaments up to 300 µm long and 7–17 µm in diameter, attached by a basal, hapteroid holdfast. Filaments in culture are similar in morphology but grow considerably longer with slightly larger cells. The cylindrical cells are multinucleate with up to eight nuclei (up to 18 in culture). Cells contain a single, parietal, lobed chloroplast with numerous small perforations and one to several pyrenoids. Zoosporangia develop by transformation of apical and subapical cells with zoids emerging through a domed pore in the apical, middle or basal part of the cell

Evolution and species boundaries of the Portieria-complex (Rhodophyta: Gigartinales)

Portieria hornemannii is a common and widespread Indo-Pacific red seaweed. Our studies suggest, however, that P. hornemannii does not represent a single species. Extremely high levels of diversity, based on mitochondrial (cox1, cox2-3 spacer) and chloroplast (rbcL, rbcL-S spacer) markers, are encountered among isolates spanning the entire geographical range of the ‘species’. Model based species delineation based on lineage through time plots reveal at least 27 species. These results are corroborated by assessments of DNA barcoding gaps. In the Philippines these individual lineages possess a near exclusive distribution pattern in the Central Visayas region, with most species restricted to one or a few localities. These observations are in stark contrast with the diversity pattern observed in the northern Batanes Islands, where a high sympatric diversity is encountered. Given the high diversity encountered at small geographical scales, we used low-copy nuclear genes (EF2 and Actin) to assess for reproductive isolation among the various lineages encountered in the Philippines. Gene trees of nuclear markers are in full concordance with the phylogenies based on organelle genes, suggesting complete reproductive isolation under natural conditions. Current efforts are dedicated at understanding the causes of this unexpected diversification, which apparently has not been accompanied by significant morphological differentiation. Ecological modes of speciation driven by herbivore interactions are investigated. The algae in question are grazed upon by Applysia sea slugs and are known to produce a wide variety of halogenated monoterpenes which act as antigrazing defense mechanisms

World Ocean Assessment II, Chapter 23, Developments in the exploration for and use of marine genetic resources

KEYNOTE POINTS 1. Marine genetic resources continue to be the focus of an expanding range of commercial and non-commercial applications. 2. Rapidly decreasing sequencing and gene synthesis costs and swift advances in the metabolic engineering and synthetic biology fields within the biotechnology sector have rendered scientists less reliant on physical samples and increasingly dependent on the exponentially expanding public databases of genetic sequence data. 3. Sponges and algae continue to attract substantial interest for the bioactive properties of their natural compounds. 4. Within the context of the Sustainable Development Goals, capacity-building issues persist, with entities in a handful of countries conducting the majority of research and development associated with marine genetic resources. 5. International processes and agreements with relevance to marine genetic resources include the Nagoya Protocol on Access to Genetic Resources and the Fair and Equitable Sharing of Benefits Arising from Their Utilization to the Convention on Biological Diversity, and the Inter-Governmental Conference on an international legally binding instrument under the United Nations Convention on the Law of the Sea on the conservation and sustainable use of marine biological diversity of areas beyond national jurisdiction.Versión del edito