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The Proceedings are composed of nine parts (See Contents). The introductory paper by Funch et al. (Part I) offers a detailed discussion of the phylogenetic position of rotifers vis-a-vis gnathi-feran groups. Originally, Gnathifera only com-prised the hermaphroditic Gnathostomulida and the Syndermata. On the basis of the ultrastructure of the trophy, the rotifers belong to the Gnathifera; moreover, molecular evidence strongly sug-gests that they are closely related to the parasitic acanthocephalans and the two together form the clade Syndermata. In his paper Mark Welch pro-vides evidence for a monophyletic Eurotatoria based on maximum likelihood and Bayesian analysis of the protein-coding gene hsp82 and for the placement of Acanthocephala within the Phy-lum Rotifera as a sister clade to either Eurotatoria or Seisonidea.
Substantial differences in both life-table char-acteristics and reproductive patterns distinguish bdelloid rotifers from monogonont rotifers. King et al. explore some of the adaptive conse-quences of these life-history differences using a Computer model to simulate the evolutionary acąuisition of new beneficial mutations. Birky et al., isolated morę than 100 females of the obli-gately asexual bdelloid rotifers from naturę and sequenced their mitochondrial cox 1 genes and conclude that in the absence of sexual reproduction the bdelloids have undergone substantial clado-genesis; bdelloid clades are adapted to different ni-ches and have undergone substantial speciation. The authors failed to detect a decrease in the eflec-tiveness of natural selection on bdelloid genes.
The development of cost-effective molecular tools that allow the amplification of minutę amounts of DNA, effectively opened the field of molecular ecology of rotifers. In Part II (Genelics and Molecular Ecology), Gómez critically reviews:
(1) methodological advances that have facilitated the application of molecular techniques to rotifers,
(2) recent advances in the field of rotifer molecular ecology, and (3) futurę developments and areas which are likely to benefit further from the molecular ecological approach. It is now feasible to obtain representative DNA sequences from identified rotifer species for use in genomic-based surveys for determining rotifers in new sample collections, circumventing the difficulties that go with traditional surveys. D.B. Mark Welch and
J.L. Mark Welch discuss in their paper the application of two genomic-based tools used in surveys of microbial communities to rotifer taxonomy: serial analysis of gene tags (SAGT) and micro-array hybridization. They also report the con-struction and hybridization of a smali microarray of rotifer sequences, thereby demonstrating that these techniques are most powerful if combined with traditional rotifer systematics.
Bdelloids show a rather uniform morphology of jaws (trophi), most recognizably feature is the presence of a series of teeth forming unci plates, each with one to ten major median teeth. Using SEM photomicrographs of trophi and literaturę data, Melone and Fontaneto deduce that few major teeth are common in species living in water bodies, where these species possibly eat unicellular algae, while morę major teeth are morę common in species inhabiting mosses and lichens, where they possibly consume bacteria.
Modern techniques can contribute significantly to our understanding of the rotifers anatomy, especially relating to the musculature and the nervous system. Very recently, immunostaining has been applied in combination with confocal laser scanning microscopy (CLSM). Santo et al., applied CLSM to describe the muscle arrangement of Brachionus urceolaris, Floscularia ringens, Hexarthra mira and Notommala glyphura. Soren-sen describes the musculature of Testudinella patina. Kotikova et al. presents data on the immuno-reactivity patterns in the nervous system of Platyas patulus, Euchlanis dilatata and Asplanchna herricki using CLSM. That species considered to be cosmopolitan can be complexes of sibling species has been recently clearly dem-onstrated for the rotifer Brachionus plicatilis: within the Iberian Peninsula three species have been described and another three have been identified (see Gómez, Part II). Gilbert and Walsh who observed mating behaviour and genetic differenti-ation among four geographically isolated strains of Brachionus calyciflorus conclude that it is a species complex in which some geographically and genetically distinct strains are reproductively isolated from one another.
Bdelloid rotifers can withstand desiccation by entering a State of suspended animation: anhy-drobiosis. Ricci and Covino describe and discuss costs and benefits of anhydrobiosis of a new
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