Variation in morphological traits over a wave-exposure gradient in one but not in another species of the brown alga Carpophyllum (Fucales)

Hodge, Fiona,Buchanan, Joseph,Zuccarello, Giuseppe C. The Korean Society of Phycology 2011 ALGAE Vol.26 No.3

Environmental conditions can influence the morphology of local biota through phenotypic plasticity or local adaptation. Macroalgal morphologies are often associated with wave-exposure conditions. We investigated the relationship between morphology and wave exposure in two common endemic subtidal macroalgae, Carpophyllum angustifolium and C. maschalocarpum, from the East Cape of New Zealand. Morphological comparisons were made between individuals from two sites and four different wave-exposure zones, as defined by fetch and barnacle composition. Of the seven morphological traits measured in C. angustifolium, only total length varied, and individuals were longer in more wave-exposed environments between the two exposure zones where the species were found. In contrast, total length, stipe thickness and vesicle presence all varied significantly between exposure zones in C. maschalocarpum. C. maschalocarpum specimens were shorter with thinner stipes, and fewer individuals had vesicles in the more wave-exposed zones. Morphological traits of both species also varied between sites, suggesting that other influences are important for determining species morphology. Further study is needed to investigate the role of phenotypic plasticity and genetic variability for driving morphological variation in C. angustifolium and C. maschalocarpum.

Variation in morphological traits over a wave-exposure gradient in one but not in another species of the brown alga Carpophyllum (Fucales)

Fiona Hodge,Joseph Buchanan,Giuseppe C. Zuccarello 한국조류학회I 2011 ALGAE Vol.26 No.3

Environmental conditions can influence the morphology of local biota through phenotypic plasticity or local adaptation. Macroalgal morphologies are often associated with wave-exposure conditions. We investigated the relationship between morphology and wave exposure in two common endemic subtidal macroalgae, Carpophyllum angustifolium and C. maschalocarpum, from the East Cape of New Zealand. Morphological comparisons were made between individuals from two sites and four different wave-exposure zones, as defined by fetch and barnacle composition. Of the seven morphological traits measured in C. angustifolium, only total length varied, and individuals were longer in more wave-exposed environments between the two exposure zones where the species were found. In contrast, total length,stipe thickness and vesicle presence all varied significantly between exposure zones in C. maschalocarpum. C. maschalocarpum specimens were shorter with thinner stipes, and fewer individuals had vesicles in the more wave-exposed zones. Morphological traits of both species also varied between sites, suggesting that other influences are important for determining species morphology. Further study is needed to investigate the role of phenotypic plasticity and genetic variability for driving morphological variation in C. angustifolium and C. maschalocarpum.

Physiological responses to salt stress by native and introduced red algae in New Zealand

Gambichler, Vanessa,Zuccarello, Giuseppe C.,Karsten, Ulf The Korean Society of Phycology 2021 ALGAE Vol.36 No.2

Intertidal macroalgae are regularly exposed to hypo- or hypersaline conditions which are stressful. However, red algae in New Zealand are generally poorly studied in terms of salinity tolerance. Consequently, two native (Bostrychia arbuscula W. H. Harvey [Ceramiales], Champia novae-zelandiae [J. D. Hooker & Harvey] Harvey [Rhodymeniales]) and one introduced red algal taxon (Schizymenia spp. J. Agardh [Nemastomatales]) were exposed for 5 days in a controlled salt stress experiment to investigate photosynthetic activity and osmotic acclimation. The photosynthetic activity of B. arbuscula was not affected by salinity, as reflected in an almost unchanged maximum quantum yield (F_v/F_m). In contrast, the F_v/F_m of C. novae-zelandiae and Schizymenia spp. strongly decreased under hypo- and hypersaline conditions. Treatment with different salinities led to an increase of the total organic osmolyte concentrations with rising salt stress in B. arbuscula and Schizymenia spp. In C. novae-zelandiae the highest organic osmolyte concentrations were recorded at S_A 38, followed by declining amounts with further hypersaline exposure. In B. arbuscula, sorbitol was the main organic osmolyte, while the other taxa contained floridoside. The data presented indicate that all three red algal species conspicuously differ in their salt tolerance. The upper intertidal B. arbuscula exhibited a wide salinity tolerance as reflected by unaffected photosynthetic parameters and strong sorbitol accumulation under increasing salinities, and hence can be characterized as euryhaline. In contrast, the introduced Schizymenia spp. and native C. novae-zelandiae, which preferentially occur in the mid-intertidal, showed a narrower salinity tolerance. The species-specific responses reflect their respective vertical positions in the intertidal zone.

Phylogeographic patterns in cryptic Bostrychia tenella species (Rhodomelaceae, Rhodophyta) across the Thai-Malay Peninsula

Bulan, Jakaphan,Maneekat, Sinchai,Zuccarello, Giuseppe C.,Muangmai, Narongrit The Korean Society of Phycology 2022 ALGAE Vol.37 No.2

Genetic diversity and distribution patterns of marine macroalgae are increasingly being documented in Southeast Asia. These studies show that there can be significant levels of genetic diversity and isolation between populations on either side of the Thai-Malay Peninsula. Bostrychia tenellla is a common filamentous red seaweed in the region and the entity is represented by at least two cryptic species. Despite being highly diverse and widespread, genetic variation and population structure of this species complex remains understudied, especially around the Thai-Malay Peninsula. We analyzed genetic diversity and inferred the phylogeographic pattern of specimens identified as B. tenella using the plastid RuBisCo spacer from samples from the Andaman Sea and the Gulf of Thailand. Our genetic analysis confirmed the occurrence of the two cryptic B. tenella species (B and C) along both coasts. Cryptic species B was more common in the area and displayed higher genetic diversity than species C. Historical demographic analyses indicated a stable population for species B, but more recent population expansion for species C. Our analyses also revealed that both cryptic species from the Andaman Sea possessed higher genetic diversity than those of the Gulf of Thailand. We also detected moderate to high levels of gene flow and weak phylogeographic structure of cryptic species B between the two coasts. In contrast, phylogeographic analysis showed genetic differences between populations of both cryptic species within the Andaman Sea. Overall, these results suggest that cryptic B. tenella species around Thai-Malay Peninsula may have undergone different demography histories, and their patterns of genetic diversity and phylogeography were likely caused by geological history and regional sea surface current circulation in the area.

Biology of Porphyra pulchella sp. nov. fromAustralia and New Zealand

Jillian C. Ackland,John A. West,Joseph Scott,Giuseppe C. Zuccarello,Judy Broom 한국조류학회I 2006 ALGAE Vol.21 No.2

Porphyra pulchella sp. nov. Ackland, West, Scott and Zuccarello was obtained at Mimosa Rock National Park, New South Wales; Westgate Bridge, Victoria, Australia; and Waihau Bay, North Island, New Zealand. It occurs mainly in mangrove habitats and is very small (± 1 mm) in field collections. In laboratory culture at 21 ± 2°C tiny blades (0.5- 3.0 mm) reproduced exclusively by archeospores liberated from vegetative cells of the upper sector of the blades. The archeospores displayed amoeboid and gliding motility once discharged. At 14 ± 2°C the blades grew to 25 mm and produced longitudinal spermatangial streaks mixed with ‘phyllosporangial’ streaks. The discharged ‘phyllospores’ showed amoeboid motility and germinated forming asexual blades. A conchocelis phase with typical bangiophycidean pit connections was observed in blade cultures after 8-10 weeks at 14 ± 2°C. Conchocelis filaments produced conchosporangia and these released amoeboid conchospores that developed into archeosporangiate blades. Molecular data indicate that all 3 isolates are genetically identical.

Biology of Porphyra pulchella sp. nov. from Australia and New Zealand

Ackland, Jillian C.,West, John A.,Scott, Joseph,Zuccarello, Giuseppe C.,Broom, Judy The Korean Society of Phycology 2006 ALGAE Vol.21 No.2

Porphyra pulchella sp. nov. Ackland, West, Scott and Zuccarello was obtained at Mimosa Rock National Park, New South Wales; Westgate Bridge, Victoria, Australia; and Waihau Bay, North Island, New Zealand. It occurs mainly in mangrove habitats and is very small (± 1 mm) in field collections. In laboratory culture at 21 ± 2°C tiny blades (0.5-3.0 mm) reproduced exclusively by archeospores liberated from vegetative cells of the upper sector of the blades. The archeospores displayed amoeboid and gliding motility once discharged. At 14 ± 2°C the blades grew to 25 mm and produced longitudinal spermatangial streaks mixed with ‘phyllosporangial’ streaks. The discharged ‘phyllospores’ showed amoeboid motility and germinated forming asexual blades. A conchocelis phase with typical bangiophycidean pit connections was observed in blade cultures after 8-10 weeks at 14 ± 2°C. Conchocelis filaments produced conchosporangia and these released amoeboid conchospores that developed into archeosporangiate blades. Molecular data indicate that all 3 isolates are genetically identical.

Holocarpic oomycete parasites of red algae are not Olpidiopsis, but neither are they all Pontisma or Sirolpidium (Oomycota)

Giuseppe C. Zuccarello,Claire M. M. Gachon,Yacine Badis,Pedro Murúa,Andrea Garvetto,Gwang Hoon Kim 한국조류학회I 2024 ALGAE Vol.39 No.1

Oomycetes are ubiquitous heterotrophs of considerable economic and ecological importance. Lately their diversity in marine environments has been shown to be greatly underappreciated and many lineages of intracellular holocarpic parasites, infecting micro- and macro-algae, remain to be fully described taxonomically. Among them, pathogens of marine red algae have been studied extensively as they infect important seaweed crops. Throughout the 20th century, most intracellular, holocarpic biotrophic oomycetes that infect red algae have been assigned to the genus Olpidiopsis Cornu. However, 18S rRNA sequencing of Olpidiopsis saprolegniae, the species considered the generitype for Olpidiopsis, suggests that this genus is not closely related to the marine pathogens and that the latter requires a nomenclatural update. Here, we compile and reanalyze all recently published 18S rRNA sequence data for marine holocarpic oomycetes, with a particular focus on holocarpic pathogens of red algae. Their taxonomy has been revised twice over the past four years, with suggestions to transfer them first into the genus Pontisma and then Sirolpidium, and into a monogeneric order, Pontismatales. We show however, that previously published topologies and the proposed taxa Pontisma, Sirolpidium, and Pontismatales are unsupported. We highlight that name changes that are unfounded and premature create confusion in interested parties, especially concerning pathogens of marine red algae that infect important seaweed crops. We thus propose that the names of these holocarpic biotrophic parasites of red algae are retained temporarily, until a supported topology is produced with more genetic markers to enable the circumscription of species and higher-level taxa.

Insights into evolution and speciation in the red alga Bostrychia: 15 years of research

Giuseppe C. Zuccarello,John A. West 한국조류학회I 2011 ALGAE Vol.26 No.1

Studies of the red algal genus Bostrychia over the last 15 years have made it a model system for many evolutionary processes within red algal species. The combination of newly developed, or first employed methods, in red algal species studies has made Bostrychia a pioneer genus in intraspecific studies. Bostrychia was the first genus in which a mitochondrial marker was used for intraspecific red algal phylogeny, and the first for which a 3-genome phylogeny was undertaken. The genus was the first red alga used to genetically show maternal plastid and mitochondria inheritance, and also to show correlation between cryptic species (genetically divergent intraspecific lineages) and reproductive incompatibility. The chemotaxonomic use, and physiological function of osmolytes, has also been extensively studied in Bostrychia. Our continuous studies of Bostrychia also highlight important aspects in algal species studies. Our worldwide sampling, and resampling in certain areas, show that intensive sampling is needed to accurately assess the genetic diversity and therefore phylogeographic history of algal species, with increased sampling altering evolutionary hypotheses. Our studies have also shown that long-term morphological character stability (stasis) and character convergence can only be correctly assessed with wide geographic sampling of morphological species. While reproductive incompatibility of divergent lineages supports the biological species nature of these lineages, reproductive incompatibility is also seen between isolates with little genetic divergence. It seems that reproductive incompatibility may evolve quickly in red algae and the unique early stages of fertilization (e.g., gametes covered by walls, active movement of spermatium nuclei to the distant egg nucleus), also well investigated in Bostrychia, may be key to our understanding of this process.

Splitting blades: why genera need to be more carefully defined; the case for Pyropia (Bangiales, Rhodophyta)

Zuccarello, Giuseppe C.,Wen, Xinging,Kim, Gwang Hoon The Korean Society of Phycology 2022 ALGAE Vol.37 No.3

The trend in naming genera based almost exclusively on molecular data, and not on morphological diagnostic characters, is increasing. In bifurcating phylogenetic trees generic cut-offs are arbitrary, but at the bare minimum nomenclatural changes should be supported by multiple phylogenetic methodologies using appropriate models for all the various gene partitions, strong support with all branch support methods, and should also result in adding to our knowledge of the interrelationships of taxa. We believe that a recent taxonomic treatment of the genus Pyropia (Yang et al. 2020) into several genera is unwarranted. We reanalysed the data presented in the recent article, using additional phylogenetic methods. Our results show that many of the newly established genera are not well supported by all methods, and the new circumscription of the genus Pyropia renders it unsupported. We also tested additional outgroups, which were previously suggested as sister to Pyropia, but this did not substantially change our conclusions. These generic nomenclatural changes of the previously strongly supported genus Pyropia, do not shed light on the evolution of this group and have serious consequences in these commercially important algae, that are also governed by a plethora of regulation and by-laws that now need to be amended. We suggest that the over-splitting of groups based only on poorly produced and modestly supported phylogenies should not be accepted and that the genus Pyropia sensu Sutherland et al. (2011) be restored.

Insights into evolution and speciation in the red alga Bostrychia: 15 years of research

Zuccarello, Giuseppe C.,West, John A. The Korean Society of Phycology 2011 ALGAE Vol.26 No.1

Studies of the red algal genus Bostrychia over the last 15 years have made it a model system for many evolutionary processes within red algal species. The combination of newly developed, or first employed methods, in red algal species studies has made Bostrychia a pioneer genus in intraspecific studies. Bostrychia was the first genus in which a mitochondrial marker was used for intraspecific red algal phylogeny, and the first for which a 3-genome phylogeny was undertaken. The genus was the first red alga used to genetically show maternal plastid and mitochondria inheritance, and also to show correlation between cryptic species (genetically divergent intraspecific lineages) and reproductive incompatibility. The chemotaxonomic use, and physiological function of osmolytes, has also been extensively studied in Bostrychia. Our continuous studies of Bostrychia also highlight important aspects in algal species studies. Our worldwide sampling, and resampling in certain areas, show that intensive sampling is needed to accurately assess the genetic diversity and therefore phylogeographic history of algal species, with increased sampling altering evolutionary hypotheses. Our studies have also shown that long-term morphological character stability (stasis) and character convergence can only be correctly assessed with wide geographic sampling of morphological species. While reproductive incompatibility of divergent lineages supports the biological species nature of these lineages, reproductive incompatibility is also seen between isolates with little genetic divergence. It seems that reproductive incompatibility may evolve quickly in red algae and the unique early stages of fertilization (e.g., gametes covered by walls, active movement of spermatium nuclei to the distant egg nucleus), also well investigated in Bostrychia,. may be key to our understanding of this process.