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National Committee on Marine Sciences (NCMS)

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AGROVOC Keyword: search.filters.agrovoc.genetic diversity (resource)Author: search.filters.author.Roleda, Michael Y.

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    Genetic diversity of Kappaphycus malesianus (Solieriaceae, Rhodophyta) from the Philippines
    Dumilag, Richard V.; Crisostomo, Bea A.; Aguinaldo, Zae-Zae A.; Lluisma, Arturo O.; Gachon, Claire M.M.; Roleda, Michael Y. (Elsevier, 2023-07)
    Kappaphycus farming for carrageenan production is characterized by a strong selective pressure at the genetic level. Traits of agronomic importance are compromised due to domestication bottlenecks and the subsequent events of possible selective breeding of founding cultivars. Kappaphycus malesianus is farmed in Malaysia and the Philippines, and is distributed within the Malesian region. While the majority of genetically characterized specimens of this species are from Malaysia, those from the Philippines are poorly explored. Here, we assessed the genetic diversity of K. malesianus from the Philippines based on cox1 sequences. Of the 15 identified haplotypes, 14 specimens represent three novel haplotypes (wild specimens) that form a group distinct from the main clade comprising most K. malesianus haplotypes known to date. An additional haplotype from a cultivated specimen was identical to that of the most widely distributed haplotype. Our findings demonstrate that the K. malesianus is genetically more diverse than previously recognized. It is expected that higher genetic diversity may be revealed through additional sampling from a wider geographic range and careful application of integrative approaches. Future selective breeding programs in Kappaphycus would benefit from the incorporation of the genetic resources, as provided in this study.
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    Trans-Arctic asymmetries, melting pots and weak species cohesion in the low-dispersal amphiboreal seaweed Fucus distichus
    Neiva, João; Assis, Jorge; Fragkopoulou, Eliza; Pearson, Gareth A.; Raimondi, Peter T.; Anderson, Laura; Krause-Jensen, Dorte; Marbà, Núria; Want, Andrew; Selivanova, Olga; Nakaoka, Masahiro; Grant, W. Stewart; Konar, Brenda; Roleda, Michael Y.; Sejr, Mikael K.; Paulino, Cristina; Serrão, Ester A. (Frontiers Media SA, 2024-04-18)
    Amphiboreal taxa are often composed of vicariant phylogroups and species complexes whose divergence and phylogeographic affinities reflect a shared history of chronic isolation and episodic trans-Arctic dispersal. Ecological filters and shifting selective pressures may also promote selective sweeps, niche shifts and ecological speciation during colonization, but these are seldom considered at biogeographical scales. Here we integrate genetic data and Ecologic Niche Models (ENMs) to investigate the historical biogeography and cohesion of the polymorphic rockweed Fucus distichus throughout its immense amphiboreal range, focusing on trans-Arctic asymmetries, glacial/interglacial dynamics, and integrity of sympatric eco-morphotypes. Populations were sampled throughout the Pacific and the Atlantic, from southern rear-edges to the high-Arctic. They were genotyped for seven microsatellites and an mtDNA spacer, and genetic diversity and structure were assessed from global to local scales. ENMs were used to compare niche divergence and magnitude of post-glacial range shifts in Pacific versus Atlantic sub-ranges. Haplotypic and genotypic data revealed distinct and seemingly isolated Pacific vs Arctic/Atlantic gene-pools, with finer-scale regional sub-structuring pervasive in the Pacific. MtDNA diversity was highly structured and overwhelmingly concentrated in the Pacific. Regionally, Alaska showed the highest intra-population diversity but the lowest levels of endemism. Some sympatric/parapatric ecotypes exhibited distinct genotypic/haplotypic compositions. Strikingly, niche models revealed higher Pacific tolerance to maximum temperatures and predicted a much more consolidated presence in the NE Atlantic. Glacial and modern ranges overlapped extensively in the Pacific, whereas the modern Atlantic range was largely glaciated or emerged during the Last Glacial Maximum. Higher genetic and ecogeographic diversity supports a primary Pacific diversification and secondary Atlantic colonization, also likely reflecting the much larger and more stable climatic refugia in the Pacific. The relic distribution and reduced ecological/morphological plasticity in the NE Atlantic are hypothesized to reflect functional trans-Arctic bottlenecks, recent colonization or competition with congeners. Within the Pacific, Alaska showed signatures of a post-glacial melting pot of eastern and southern populations. Genetic/ecotypic variation was generally not sufficiently discontinuous or consistent to justify recognizing multiple taxonomic entities, but support a separate species in the eastern Pacific, at the southern rear-edge. We predict that layered patterns of phylogeographic structure, incipient speciation and niche differences might be common among widespread low-dispersal amphiboreal taxa.
    The authors thank Marta Valente (CCMAR), André Silva and Diogo Brito for sequencing and genotyping work and all the people involved in sample collection. Samples from Logy Bay were kindly collected by Kyle R. Millar. DK-J and NM thank Hurtigruten’s FRAM cruise for help with sampling along the Greenland west coast. Greenland sampling was also connected with campaigns for the MarineBasis component of the Greenland Ecosystem Monitoring (GEM) Programme in Nuuk and Young Sound, which is acknowledged.