An Integrated Study of the Species Problem in the Euplotes crassus‐minuta‐vannus Group¹

Abstract

ABSTRACT. In an attempt to solve the ambiguity in the taxonomy of the Euplotes crassus, minuta, and vannus group, 19 strains were tested for mating interactions, electrophoresed for isozymic variations, and analyzed by multivariate morphometrics of the conventional diagnostic traits. The overall results supported the validity of the three named species. Inter‐specific mating occurred only in a few crassus x vannus strain combinations and was usually inviable. Isozymic variations, in particular of amylases, malic enzyme, and malic dehydrogenase, were very restricted within conspecific strains and were great between non‐conspecifics. The species ascertainment of the strains was possible on the basis of clustering and principal component analyses of morphological measures.

Isozyme characterization of three Antarctic species of the hypotrich ciliateEuplotes

“…The zymograms produced for ACP, AMY, MDH, ME and TO by the strains of the three Antarctic Euplotes species, as well as by strain LL, of E. crassus of origin from a temperate area (Valbonesi et al, 1988) and analyzed as a standard reference strain, are diagrammatically illustrated in Figure 1. Only bands which were markedly stained and regularly visualized have been reported, and their relative breadths accordingly indicated as boxes and lines.…”

“…Enzyme extraction, electrophoretic running conditions, and gel staining were as described in Valbonesi et al (1988).…”

“…All fall into the large group of Euplotes species characterized by both an argyrome (i.e., the mosaic-like complex of cortical alveoli underlying the plasma membrane) of «double» type and a set of nine fronto-ventral ciliary cirri. As some wild strains representative of each one of these species could be expanded into laboratory cultures with cell densities high enough to be used in the preparation of substantial amounts of biological macromolecules, we analyzed the electrophoretic patterns of five enzyme systems, namely acid phosphatases (ACP), amylases (AMY), malic dehydrogenases (MDH), malic enzyme (ME), and tetrazolium oxydases (TO), of proven diagnostic value in Euplotes systematics (Valbonesi et al, 1988). The results of these analyses are described here; they provide further evidence that E. focardii, E. euryhalinus, and E. nobilii are separate and identifiable evolutionary entities.…”

Polygenic control of an all-or-none morphological trait in Euplotes (Ciliata, Hypotrichea). Evolutionary significance of naturally occurring morphological variation in Ciliates

“…Within it, 3 entities can be separated on the basis of morphometric, biochemical and ecological criteria (Machelon et al, 1984;G6nermont et al, 1985;Valbonesi et al, 1988;Gianni and Piras, 1990). Since the 3 kinds of criteria provide arguments in very good agreement with each other, it may reasonably be assumed that these entities are monophyletic taxonomic units.…”

Single-cell PCR on protargol-impregnated euplotid ciliates: a combined approach of morphological and molecular taxonomy

“…Furthermore, euplotids have been more comprehensively investigated than other ciliates. Nevertheless, euplotid species cannot be easily distinguished on the basis of morphological differentiation due to dimorphism or sibling species, and consequently taxonomical debates continue to arise (Nobili 1966;Machelon et al 1984;Génermont et al 1985;Valbonesi et al 1988). Notably, because of the sensitive response of cell activities to xenobiotic compounds, euplotids can be used as pollution indicators in aquatic ecosystems.…”