Algal Parasite <i>Herpodiscus durvillaeae</i> (Phaeophyceae: Sphacelariales) Inferred to have Traversed the Pacific Ocean with its Buoyant Host

Fraser, Ceridwen I.; Waters, Jonathan M.

doi:10.1111/jpy.12017

Cited by 12 publications

(3 citation statements)

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“…Further sampling could help to clarify the direction of travel. Our finding supports previous inferences of long-distance dispersal of marine pathogens via rafting with buoyant macroalgae (Fraser and Waters 2013;Blake et al 2017). Blake et al (2017) found M. ectocarpii in Australia on bull kelp taxa D. potatorum and D. amatheiae, so we might have expected to find M. ectocarpii in New Zealand (geographically relatively close to Australia), but these solid-bladed Durvillaea species are non-buoyant and thus have limited dispersal opportunities (Fraser et al 2020;Hay 2020).…”

Section: Resultssupporting

confidence: 89%

“…This trait has promoted long-distance dispersal of Durvillaea species such as D. antarctica, which has been found washed up on coasts thousands-and even tens of thousands-of kilometres away from known source populations (Moore and Cribb 1952;Fraser et al 2011Fraser et al , 2018Waters et al 2018). These buoyant species are an important mechanism for the dispersal of coastal taxa, as they can transport other organisms with them, such as invertebrates, other algal species, and marine parasites (Thiel and Gutow 2005a, b;Fraser and Waters 2013). Emerging data showing a wide distribution of Maullinia across the Southern Hemisphere suggest that Maullinia might also disperse with these buoyant hosts.…”

Section: Introductionmentioning

confidence: 99%

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Pathogen inferred to have dispersed thousands of kilometres at sea, infecting multiple keystone kelp species

2021

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Protistan pathogens have been found to infect populations of some large brown macroalgae. Infection could reduce the ability of macroalgae to withstand hydrodynamic pressures through weakening tissues and reducing flexibility. Widespread mortality of macroalgae if disease outbreaks were to occur could have important flow-on consequences for biodiversity and ecosystem function. Recent discoveries of the protistan pathogen Maullinia infecting the ecologically keystone southern bull kelp Durvillaea in Chile, Australia, and on Marion Island, raise the possibility that this pathogen is dispersing across ocean basins with buoyant hosts. To determine whether Maullinia also infects southern bull kelp in New Zealand, samples of gall-like tissue from Durvillaea antarctica, D. poha, and D. willana were collected from intertidal sites, and genetic analyses (sequencing of partial 18S rRNA) carried out. Maullinia infections were detected in all three species of Durvillaea. Phylogenetic analyses show a close relationship of New Zealand Maullinia to M. braseltonii previously detected in Chile and on Marion Island. Based on its genetic similarity to distant lineages and its presence on buoyant hosts that have been shown to drift long distances at seas, we infer that Maullinia has dispersed across the Southern Ocean through rafting of infected bull kelp. Understanding the capacity of pathogens to disperse across oceans is critical part of forecasting and managing ecosystem responses to environmental change.

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Section: Resultssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Pathogen inferred to have dispersed thousands of kilometres at sea, infecting multiple keystone kelp species

2021

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“…Phylogenetic studies have become a common tool to identify new parasite species (Sekimoto et al 2009;Skovgaard & Salomonsen 2009), investigate their origin (Litaker et al 1999;Skovgaard et al 2007;Barkman et al 2008) and host switching (Fraser & Waters 2013;Pelser et al 2016). Molecular data are still rather limited for red algal parasites with only 27% of all red algal parasites having been sequenced (Chapter 2).…”

Section: Diversity and Evolution In Parasitesmentioning

confidence: 99%

Investigating diversity, evolution, development and physiology of red algal parasites from New Zealand

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<p>Red algal parasites have evolved independently over a 100 times and grow only on other red algal hosts. Most parasites are closely related to their host based on the similarity of their reproductive structures. Secondary pit connections between red algal parasites and their hosts are used to transfer parasite organelles and nuclei into host cells. Morphological and physiological changes in infected host cells have been observed in some species. Parasite mitochondrial genomes are similar in size and gene content to free-living red algae whereas parasite plastids are highly reduced. Overall, red algal parasites are poorly studied and thus the aim of this study was to increase the general knowledge of parasitic taxa with respect to their diversity, evolutionary origin, development, physiology, and organelle evolution. Investigation of the primary literature showed that most species descriptions of red algal parasites were poor and did not meet the criteria for defining a parasitic relationship. This literature study also revealed a lack of knowledge of many key parasitic processes including early parasite development, host cell “control”, and parasite origin. Many of these poorly studied research areas were addressed in this thesis. Phylogenetic analyses, using a range of markers from all three genomes (cpDNA: rbcL, nDNA: actin, LSU rRNA; mtDNA: cox1), showed different patterns of phylogenetic relationships for the four new red algal parasites and their hosts. The parasites Phycodrys novae-zelandiophila sp. nov. and Vertebrata aterrimophila sp. nov. closest relative is its host species. Cladhymenia oblongifoliophila sp. nov. closest relative is its host species based on nuclear and mitochondrial markers whereas the plastid markers group the parasite with Cladhymenia lyallii, suggesting that the parasite plastid was acquired when previously parasitizing C. lyallii. Judithia parasitica sp. nov. grows on two Blastophyllis species but the parasites’ closest relative is the non-host species Judithia delicatissima. Developmental studies of the parasite Vertebrata aterrimophila, showed a unique developmental structure (“trunk-like” cell) not known in other parasites, plus localised infection vi and few changes in infected host cells. High-throughput-sequencing revealed mitochondrial genomes of similar size, gene content and order in the parasite Pterocladiophila hemisphaerica to its host Pterocladia lucida, and a reduced non-photosynthetic plastid in the parasite. Mitochondrial (mt) and plastid (cp) genome phylogenies placed Pterocladiophila hemisphaerica on long branches, either as sister to Ceramiales (mt) or Gracilariales (cp). Further analyses, filtering non-elevated plastid genes grouped the parasite neither with the Gracilariales (mt) or Gelidiales (cp) on shorter branches but without support. Nuclear phylogeny grouped P. hemisphaerica as sister to the Gelidiales and other red algal orders and was the only phylogenetic relationship with support. Investigations of photosystem II capacity using PAM fluorometry, and quantifying chlorophyll a content in three pigmented parasites, showed different host nutrient dependencies. Rhodophyllis parasitica and Vertebrata aterrimophila are not able to photosynthesize and are fully dependent on host nutrients. Pterocladiophila hemisphaerica is able to photosynthesize independently, even though it has a reduced non-photosynthetic plastid genome, and therefore is only partially dependent on its host. This study advances our current understanding of red algal parasites and highlights many possibilities for future research including genome evolution and understanding parasite diversity.</p>

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Detached Seaweeds as Important Dispersal Agents Across the Southern Ocean

et al. 2020

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Algal Parasite Herpodiscus durvillaeae (Phaeophyceae: Sphacelariales) Inferred to have Traversed the Pacific Ocean with its Buoyant Host

Cited by 12 publications

References 15 publications

Pathogen inferred to have dispersed thousands of kilometres at sea, infecting multiple keystone kelp species

Pathogen inferred to have dispersed thousands of kilometres at sea, infecting multiple keystone kelp species

Investigating diversity, evolution, development and physiology of red algal parasites from New Zealand

Detached Seaweeds as Important Dispersal Agents Across the Southern Ocean

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