Syringodermatales ord. nov. and Syringoderma floridana sp. nov. (Phaeophyceae)

Henry, Eric C.

doi:10.2216/i0031-8884-23-4-419.1

Cited by 40 publications

(27 citation statements)

References 4 publications

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“…The Sphacelariales share apical growth, a plesiomorphic character in brown algae, with several other phaeophycean orders, such as the Syringodermatales, Dictyotales, Scytothamnales, Cutleriales and Fucales (Henry, 1984;van den Hoek et al, 1995;Reviers & Rousseau, 1999), but they are distinguished from all other brown algae by the transitory blackening of their cell walls by Eau de Javel (Reinke, 1890;Migula, 1909;Prud'homme van Reine, 1982;Reviers & Rousseau, 1999). Members of the Choristocarpacecae and Onslowiaceae, which were in the past included in the Sphacelariales s.l.…”

Section: Discussionmentioning

confidence: 99%

“…Instead, the life history of H. durvillaeae resembles that of Syringoderma floridana Henry, a member of the Syringodermatales. Syringoderma floridana has a macroscopic sporophyte and a reduced gametophyte, which settles on the sporophyte and turns entirely into a gametangium (Henry, 1984). Consequently, Henry (Peters, 1990; E. C. Henry, personal communication) suggested H. durvillaeae might have affinities with the Syringodermatales.…”

Section: Introductionmentioning

confidence: 99%

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Affiliation of the parasiteHerpodiscus durvillaeae(Phaeophyceae) with the Sphacelariales based on DNA sequence comparisons and morphological observations

Heesch

Peters²,

Broom

et al. 2008

European Journal of Phycology

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The phylogenetic affinities of the brown alga Herpodiscus durvillaeae, an obligate parasite of Durvillaea antarctica (Fucales, Phaeophyceae) endemic to New Zealand, were analysed using combined partial nuclear encoded ribosomal DNA (26S) and plastid encoded RuBisCO (rbcL) gene sequences. Results from phylogenetic analyses place this species within the order Sphacelariales. Molecular data were supported by two morphological features characteristic for the Sphacelariales sensu stricto: the presence of apical cells and the transitory blackening of the cell wall with sodium hypochlorite solution ('Eau de Javel'). However, the strongly heteromorphic life history distinguishes H. durvillaeae from all other members of the Sphacelariales of which the life cycle is known. This variability in life history provides a new systematic character for the order and should be taken into account in any comprehensive systematic revision of the Sphacelariales.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Affiliation of the parasiteHerpodiscus durvillaeae(Phaeophyceae) with the Sphacelariales based on DNA sequence comparisons and morphological observations

Heesch

Peters²,

Broom

et al. 2008

European Journal of Phycology

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“…(This latter inference from the molecular data is in conflict with morphologically based interpretations, and continues to be controversial.) Highly reduced gametophytes have also evolved in Syhgodma, and in one species are sessile on the sporophyte (Henry, 1984); here, a case for the sequential evolution of diploidy might be made, but there are no intermediate forms with freeliving gametophytes of moderate size. It is a peculiarity of this theory that it can explain the exaggeration of diploid but not of haploid growth.…”

Section: The Complementation Of Deleterious Recessive Mutationsmentioning

confidence: 97%

The evolution of the life cycle of brown seaweeds

Bell

1997

Biological Journal of the Linnean Society

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The brown seaweeds (Phaeophyta) are well-suited for testing theories of the evolution of the sexual alternation of haploid and diploid generations because of the great diversity of life cycles within the phylum. Three theories are investigated in this paper. (1) Diploid growth evolves because it has the effect of complementing deleterious recessive mutations. This is rejected because (a) ancestral haplonty is not a parsimonious inference from current phylogenies; (b) the exaggeration of diploid growth does not evolve in a comb-like fashion; (c) forms with predominantly haploid growth have evolved from smaller isomorphic ancestors; and (d) there is no correlation between haploid growth and monoecy. (2) Diploid growth evolves when gamete dimorphism leads to intense sexual selection, favouring the production of genetically diverse gametes through meiosis. This is rejected because there is no correlation between the dominance of the diploid generation and the degree of gamete dimorphism. It is possible to show that gamete dimorphism itself has evolved in the Phaeophyta through the increase in size of the macrogamete in forms that have evolved larger sporophytes. (3) Microthalli become specialized as gametophytes because fusion is promoted by releasing gametes into the boundary layer; macrothalli become specialized as sporophytes because dispersal is promoted by releasing zoospores into the water column. This is consistent with the sexual and reproductive biology of Phaeophyta. The classic sexual cycle can then be interpreted as evolving from an asexual alternation of microthallus and macrothallus, governed largely by environmental factors, through selection for the appropriate association of ploidy with vegetative size. The exceptions to this general rule are forms in which gametes are released from rnacrotlialli, where a different suite of sexual characters has evolved. 81997 The Linnean Socicty of London ADDITIONAL KEY WORDS -haploidy -diploidy -sex -alternation of generations -Phaeophyta

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“…There are very few organisms that regularly develop as groups of between 2 and 10 cells. We have been unable to identify any organisms that comprise two differentiated cells: Gonium (Chlorophyta; Bold & Wynae, 1978) and the gametophyte of ~ringodmuJondana (Phaeophyta; Henry, 1984) are two-celled but undifferentiated. Indeed, there seem to be very few examples of differentiated organisms with fewer than a hundred cells: colonial Volvocales such as Pleodorina, the endoparasitic dicyemid mesozoans and the enigmatic Salinella.…”

Section: Q Small D#mtiated Organisms Seldom Euolvementioning

confidence: 99%

Size and complexity among multicellular organisms

Bell

Mooers

1997

Biological Journal of the Linnean Society

179

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The diversity of specialized cell types ('complexity') is estimated for a wide range of multicellular organisms. Complexity increases with siize, independently of phylogeny. This is interpreted in economic terms as the consequence of a greater degree of cooperative division of labour within larger entities. The rate of increase of complexity with size is less in the case of a cooperative division of labour (cell types withii bodies) than in the analogous case of a competitive division of labour (species within communities). This is atttributed to the inutility of single specialized cells whose goods must be shared among all the many cells of a large organism. Major groups of organisms differ in complexity at given size: animals are more complex than plants, and phaeophytes are simpler than either.

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Syringodermatales ord. nov. and Syringoderma floridana sp. nov. (Phaeophyceae)

Cited by 40 publications

References 4 publications

Affiliation of the parasiteHerpodiscus durvillaeae(Phaeophyceae) with the Sphacelariales based on DNA sequence comparisons and morphological observations

Affiliation of the parasiteHerpodiscus durvillaeae(Phaeophyceae) with the Sphacelariales based on DNA sequence comparisons and morphological observations

The evolution of the life cycle of brown seaweeds

Size and complexity among multicellular organisms

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