Marine biological diversity: problems, comments, methodology of researches

Andrey V. ADRIANOV

Institute of Marine Biology FEB RAS, Vladivostok, 690041, Russia, inmarbio@mail.primorye.ru

Terminology and six main levels of biodiversity have been suggested and discussed. Species richness and taxonomic diversity of terrestrial, freshwater and marine organisms are compared based on a new quantitative estimations. About 1.5 million of terrestrial species and 320 000 species of water organisms have been described up date. Despite more than 200 years of intensive researches biologists have described only about 280 000 marine species including about 180 000 marine invertebrates. Of the 33 phyla of Metazoa listed in the text, 31 phyla are found in the sea, 13 of which are exclusively marine. Only 17 phyla are found in the fresh water and 11 phyla are found in terrestrial environments. Only two phyla, the fresh water Micrognathozoa, and the terrestrial Onychophora, are thought to be non-marine endemics. What does it mean for forming of marine biodiversity? Marine diversity in the coral reef, coastal environments, deep-water macrobenthos and in meiofauna are calculated and discussed. Number of species for all of the metazoan phyla are quantified. Approximately 25 million undescribed macrobenthic species and about 20-30 million of meiobenthic species, including more than 10 millions of marine nematodes, are suggested in the deep-sea based on modern extrapolations. Hypothesis explaining high benthic species diversity in the deep-sea sediments are summarized. New global and regional initiatives, methodology of marine researches and biodiversity research methods are discussed.

Multikingdom system of the living things

Anatoly L. DROZDOV

Institute of Marine Biology FEB RAS, Vladivostok, 690041, Russia, inmarbio@mail.primorye.ru

The five-kingdom system of cellular organisms suggested in 70s (Whittaker, 1969; 1977; Whittaker, Margulis, 1979; Margulis, 1974; 1981; Margulis, Schwartz, 1982; 1988)) is in common use now. This system was primarily associated with sharp expansion of researches in microanatomy, cytology, and cytochemistry, especially those using ultramicroscopical techniques. In addi­tion, numerous investigations were conducted in the area of phylogenetic cladistics of Hennig, genetic systematics, karyology, comparative biochemistry, immunology, and a number of other rapidly developing scientific disciplines. The five kingdoms are included into this system: three higher kingdoms of plants, fungi, and animals, and two lower kingdoms: eukaryotic Protista and prokaryotic Monera. L. Margulis clearly delineated the kingdom Protoctista from the three superior kingdoms and transferred to it all algae, all flagellate forms of fungi, and fungilike organisms. She thus made monophyletic the kingdoms of plants, fungi, and animals but increased the heterogeneity of the kingdom Protoctista. L. Margulis herself frankly admitted that "the protoctist kingdom becomes looking as if it were a dump". Retaining algae in the plant kingdom and diploid water moulds in the kingdom of fungi, she "straightforwardly admitted the polyphyletic nature of the plant and animal kingdoms". From these words of L. Margulis, it unambi­gu­ous­ly follows that all schemes with few eukaryotic kingdoms (1 to 4) will err toward inadmis­sible polyphyly, as is confirmed by contemporary cytological and, especially, molecular biology data. The studying of bacteria indicated the two different groups: Eubacteria and Archaebacteria (Archae). The multikingdom system of the living things advanced by us (Kussakin, Drozdov, 1994, 1998) comprises 11 kingdoms of prokaryotes and 15 kingdoms of eukaryotes. It was based on the principle of conservatism of cellular structures formulated by V.F. Mashansky and A.L. Drozdov (1975; 1988). In these works, we made an attempt to analyze a biological paradox: at the molecular, cellular, organismic, population, and species levels, biological diversity is astonishing, while the subcellular and organoids levels are extremely conservative. There are only two major ultrastructural patterns of biological membranes and 7-8 patterns of structure of cell walls, 2-3 patterns of ribosomes, 3-4 patterns of organization of synthetic apparatus, and only six patterns of ultrastructural organization of plastids, 4-5 patterns of organization of mitochondria, 3 patterns of organization of nuclear apparatus, and 7-8 patterns of organization of kinetic apparatus. We postulated that organisms having the same structure of cellular organelles belong to the same kingdom of living organisms. "Kingdom" is an objective taxonomic category, as it is in the case with "species". We represented our system in two modus - as a table and as a drawing.

The database of class Nematoda from the Sea of Japan

Natalia P. FADEEVA*, Olga I. DASHCHENKO**

Far East State University, Vladivostok, 690600, Russia, *nfadeeva@mail.primorye.ru, **dashcha@bio.dvgu.ru

The collection of free-living marine nematodes of Zoology Department of Far Eastern State University is growing since 70th. Now it has about 10 thousand individuals and more than 280 species (including type specimens) of marine nematodes from the Sea of Japan. Moreover there is material from the Far Eastern Seas, Japan, Vietnam, Indian Ocean, the Pudget Sound Bay, New Zealand and Australia. The systematic database of class Nematoda from the Sea of Japan using the Access 2000 has been created with the purpose of systematization and representation of the material in the convenient form for perception and operation. The database contains 15 tables, 10 of which represent taxa (subclass, order, suborder, family, subfamily, tribe, subtribe, genus, subgenus, species), and 5 have keys for the identification. Currently the diagnoses of 110 genera registered in the Sea of Japan are in a database. The following names of fields are presented: "A species Code", "A name of species for searching", "Species", "Description of species", "Ecological data", "Geographical distribution", "Literary data", "Male", "Female", "Types", "Material", "Figure", "Legend of figure". The name of a field "A species Code" is a counter, in case of adding a new species to the database it is automatically appropriated a numeral code. The Fields "A name of species for searching" and "Species" are text. It is possible to include to a text field the information no more than 255 symbols length. The field of "Figure" contains subjects such as OLE (drawings, EXCEL table, WORD documents etc.), in remaining fields data are situated such as MEMO. 4 elements were used for control such as: a legend, a button, a drawing and a rupture of page in the database. The database is initial stage of registration of nematofauna and bionomics of the Sea of Japan. It will be completed periodically due to new data. The database will facilitate an identification quality control to the specialists.

Phylogeny of Bursaphelenchus conicaudatus, and its vector, Psacothea hilaris

Natsumi KANZAKI*, Kazuyoshi FUTAI**

Laboratory of Environmental Mycoscience, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan, *kanzaki@kais.kyoto-u.ac.jp, **futai@kais.kyoto-u.ac.jp

In order to examine whether or not the co-speciation occurs in a phoretic relationship, molecular phyogenetic analysis on Bursphelenchus conicaudatus, and its phoretic host, Psacothea hilaris was conducted. The beetle is widespread in Japan, Taiwan, and the continental China, and is divided into 13 geographical subspecies. First of all, ten subspecies of the beetle were collected in various districts of Japan, and the molecular phylogenetic analysis based on the cytochrome oxidase subunit I in the mitochondrial DNA was conducted both for the nematode isolates and for its vector beetle subspecies. The analysis divided 30 isolates of nematodes obtained from 10 subspecies of beetles into five isolate groups and 10 subspecies of beetles (totally 40 individuals) into four subspecies groups, respectively. The nematode isolate groups and the beetle subspecies groups were corresponding to each other, and the mechanism of the co-speciation could be related to the paleogeography of Japan, though there were several discrepancies. Intraspecific vector replacements were supposed to occur in the isolates of B. conicaudatus on two islands. These discrepancies were found between nematode isolates and their corresponding beetle subspecies and were assumed as concomitant to the migration process of the beetle and/or the nematode populations, i.e., a beetle population and its associate nematode population on an island might have migrated from different provinces. These results suggest that 1) the co-speciation can occur in a phoretic association between the nematodes and the beetles, and 2) the co-speciation could be disturbed by extinction and re-migration of populations.

New ideas on the animal phylogeny and the position of nematodes in the system of animal kingdom

Vladimir V. MALAKHOV

Faculty of Biology, Moscow State University, Moscow, 119992, Russia, vmalakhov@mtu-net.ru

Molecular biology introduced new ideas into phylogenetic investigations. As a result of DNA sequence study, the new taxa were created and the animal classification changed drastically. Nematodes fell within the new superphylum taxon Ecdysozoa. In modern classification, nematodes are coupled with Arthropoda, Onychophora, Tardigrada, and Cephalorhyncha instead of previously accepted conceptions on the relation of nematodes to turbellarians, gastrotrichs, rotifers etc. The total lack of ciliary epithelia, strong cuticularization, absence of intracuticular microvilli and molting, disappearance of trochopore larvae, non-spiral type of cleavage, lack of true coelom, the absence of free nerve endings and setae-like sensilla, and other features of nematode morphology and development could be explained on the basis of the derivation from ecdysozoan ancestor. The adoption of the ecdysozoan conception makes us to assume the evolutionary reduction of limbs and segmentation in nematode ancestor as a result of burrowing habits. The evolutionary model of nematode origin could be roughly pictured as a row Onychophora-Tardigrada-Nematodes.

Parasitic Dwarf Males: Biology and Evolutionary Implications

Alexei V. RYBAKOV

Institute of Marine Biology FEB RAS, Vladivostok, 690041, Russia, avr@eastnet.febras.ru

Dwarfs represent an extreme case of sexual dimorphism, when highly reduced males inhabit the female providing immediate fertilization of deposited eggs. They are rather widespread, being particularly common, when contacts between specimens of different sex are difficult (due to low population densities, sessile or parasitic mode of life, "patchiness" of the habitats, etc.). In these cases we could observe development of some peculiar reproductive strategies, comprising hermaphroditism, self-fertilization, or asexual reproduction. However, presence of cross-fertilization in life cycle provides obvious selective advantages, therefore long-term (or even lifetime) associations between specimens of different sex sometimes appear the most favorable, often resulting in the development of dwarf males. Dwarfism provides some important advantages. There is no need of search for breeding partners. The development of such males is much faster and the need for metamorphosis with its inherent risks is often reduced, as many dwarfs exhibit neoteny. Dwarfism also minimizes negative effects on a host that otherwise would have at least two large parasites. The associated expenses are just those of spermatogenesis, with a little more to support certain somatic growth (as the males are usually extremely reduced). Sperm production is thought to be relatively cheap, so the cost to the female for hosting even several dwarfs would be not too high. Female organism provides a habitat for such an "integrated" male and performs most of its life activities (except spermatogenesis). To host the dwarfs, females acquire some particular organs (pockets, cavities, or male receptacles of different kinds), sometimes of a complicated structure. These adaptations benefit the parasitism of the dwarf males, favoring their fast and profound degeneration. The processes associated with the development of dwarfism are very similar to those observed during the course of evolution in parasites. The phenomenon of dwarf males might be considered as a peculiar pattern of intraspecific parasitism.

Master of Science in Nematology: a success story

Nic SMOL

PINC, Vakgroep Biologie, Universiteit Gent, Ledeganckstraat, 35; B-9000, Gent, Belgium, nic.smol@UGent.be

The Postgraduate International Nematology Course at Ghent University has been created in 1992 to meet the needs of educating of students and scientist in Nematology. Most of the students are coming from developing countries, all over the world. The course started with 7 students and gradually increased to the present batch of 18 students, chosen out of about 90 applications. Within the past 10 years 98 students have obtained the degree of "Master of Science in Nematology". The results of the past decade are discussed and future prospectives, such as the new programme, are explained. In view of the European unification of the diplomas and the consequent introduction of the Bachelor and Master degree, new ideas for switching from one year to two years programme are discussed. Details about the admission requirements, possible scholarships and miscellaneous will be given.

Caenorhabditis elegans - 2002 Nobel prize winner

Sergei E. SPIRIDONOV

Institute of Parasitology of RAS, Leninskii pr. 33, Moscow, 117071, Russia, spiridon@rjnem.msk.ru

"2002 Nobel Prize for worms", i.e. presentation of the highest scientific prize for three well known specialists (S. Brenner, H.P. Horvitz, J. Sulston) in Caenorhabditis elegans developmental biology and genetics was an outstanding event of last year. Surely it was accepted with satisfaction in numerous laboratories dealing with modern developmental biology, but such a decoration is simultaneously sending very clear and powerful message to nematological community as a whole. International scientific community is paying a tribute not only to terribly profound studies in biology of single animal species, but in fact single and simple decision made more than four decades ago is pinpointed - an idea to use nematodes as biological models for developmental biology. Immanent features of nematodes and participation of elite biological workforce were probably two main factors, which produced such revolutionary results. Classical nematology was crucial to choose C. elegans as model object, with researchers like Nigon witnessing the nematode virtues. On early stages of these investigations, nematodes as transparent creatures of few hundreds of cells were studied in very straightforward way - observing the cell divisions under microscope. It means that first steps in this huge progress were made with principally the same tools and methods as those still common for classical nematology. Even morphological facts about C. elegans considered alone - apart from developmental and genetical data - are making this nematode the best morphologically studied nematode object. (Let we mention here only "curcuit scheme" - fully mapped contacts between cells in nerve system.) Basic observation - the fact of programmed cell deaths in C. elegans development - was made by John Sulston after light microscopic examination of embryonic development. Discovered developmental and morphological facts about C. elegans can be directly applied to wider scope of nematological researches. But the clear message for all the community of classical nematologists is even more important - unbiased analysis of the data obtained with quite common methods of nematode examination (light microscope, TEM) could bring much more features of nematode organization than it is routinely used in nematology practice.

Benthimermithidae: a review of an enigmatic marine nematode group

Alexey V. TCHESUNOV¹, Dmitrii M. MILJUTIN²

¹Department of Invertebrate Zoology, Faculty of Biology, Moscow State University, Moscow, 119899, Russia, tchesunov@mtu-net.ru

²Federal Research Institute of Fisheries & Oceanography, Moscow, Russia, dmilutin@mtu-net.ru

The family Benthimermithidae comprises marine and mainly deep-sea nematodes parasitizing at larval stages in internal organs of benthic invertebrates. Adult stages leave their hosts and dwell freely. Since benthimermithids have a modified alimentary tract devoid a mouth and normal pharynx, they obviously feed through body wall during larval parasitism and do not feed at adult stage. Larval stages possess a stylet-like structure and glandular pharynx. Adults provide some characters (cephalic and somatic setae, lateral amphids and serial supplementary organs) indicating their relationships to free-living nematodes. The family consists of three genera, two of them (Trophomera and Adenodelphis) are monotypic, whilst the third genus Benthimermis includes over 30 species. Future synonymization of Trophomera Rubzov & Platonova 1974 and Benthimermis Petter 1980 is possible. Benthimermis is a highly diversified genus, which species vary in length from 1 mm to 17 cm. Benthimermis species demonstrate different stages of fusion of male gonads from two distinct parallel testes to one united gonad and a variety of ovary types (reflexed and outstretched, telogonic and hologonic). The majority of species is described on the base of either males or females while both sexes are known for a few species only. This circumstance poses difficult taxonomic problems within the family. (RFFI grant No. 03-04-49152).

Oogenesis in free-living aquatic nematodes: ultrastructural aspects

Vladimir V. YUSHIN¹, Vladimir V. MALAKHOV²

¹Institute of Marine Biology FEB RAS, Vladivostok, 690041, Russia, yushin@fromru.com

²Department of Biology, Moscow State University, Moscow, 119899, Russia, vmalakhov@mtu-net.ru

Original data on the oogenesis in 11 species of free-living aquatic (marine and fresh water) nematodes belonging to the orders Enoplida, Mononchida, Chromadorida, Desmodorida, Monhysterida and Plectida are reviewed. Free-living aquatic nematodes have the basic pattern of oogenesis (solitary oogenesis) and vitellogenesis (authosynthesis) described in a variety of parasitic species. The vitellogenic oocytes show great synthetic activity. Voluminous nuclei have nuclear envelope with numerous nuclear pores; the nucleoplasm contains from one to several large nucleoli. Cytoplasm is filled with ribosomes, cysternae of rough endoplasmic reticulum (RER), Golgi bodies, and mitochondria. The RER is organized into stacks and whorls. The surface area of the vitellogenic oocytes is highly increased by development of numerous microvilli or another surface modifications (infoldings, outfoldings, large processes). Phagocytosis and pinocytosis, which are indicators of heterosynthetic vitellogenesis, have not been detected. The vitellogenesis results in formation of two basic types of yolk: (i) proteinaceous membrane-bound granules and (ii) lipid droplets. The special type of granules, which are enveloped by membrane but have characteristic heterogeneous matrix, was found in estuarine (Enoplida-Tripyloidina) and fresh-water (Enoplida-Tobrilina, Mononchida, Plectida) species. Analogous granules are well known in a variety of terrestrial and parasitic nematodes as the heterogeneous or shell granules. These granules are utilized during rapid egg-shell formation after fertilization. Synthesis of the shell granules correlates well with adaptation of nematodes to such an unfavourable habitat as fresh water, soil, terrestrial plants, and digestive system. (Support for Science Schools grant No. 1219.2003.4).

© Russian Society of Nematologists, Institute of Marine Biology FEB RAS, 2002