Allopolyploid speciation in Siberian Dactylorhiza (Orchidaceae, Orchidoideae)

Morphological and allozyme analyses of Siberian dactylorchids have revealed the presence of a new, previously undescribed allopolyploid that is described here as species new to science. The genetic constitution as revealed by allozyme analysis of this species confirms that its parents are the diploid Siberian D. fuchsii and D. incarnata, and it is 2n=80, representing the first such count from the Asiatic Russia. In most literature surveys of Siberia, the new species has been identified as D. baltica, which is different in the allele composition of the pgi locus. Morphologically, both allotetraploids are similar; D. sibirica is distinguishable due to the absence of spots on the leaves and a narrower lip with narrower lateral lobes. A brief summary of Dactylorhiza allopolyploids from Siberia (Russia) is presented.

Morphological diversity and widespread hybridization in the genus Bythotrephes leydig, 1860 (Branchiopoda, Onychopoda, Cercopagidae)

Morphological variation in the genus Bythotrephes was studied. We analyzed samples from 29 locations through the generic range. Based on the core body length and the total length, as well as several other morphological characters, differences were found that are consistent across five groups of populations previously described as a separate species (B. cederstroemii, B. crassicaudus, B. transcaucasicus, B. brevimanus, and B. longimanus). Individuals with intermediate morphological characteristics were detected where B. cederstroemii, B. brevimanus and B. crassicaudus have geographic overlap. Based on allozyme analysis, hybrids of B. cederstroemii and B. brevimanus were revealed in the zone of contact of these two species in the Volga River drainage and northwestern Russia.

Allozyme analysis of Haemonchus contortus resistant and susceptible to anthelmintics, with an indication of dipeptidases associated with resistance

In an attempt to investigate the genetic and biochemical causes underlying resistance to anthelmintics, the trichostrongylid nematode Haemonchus contortus was examined by an allozymic analysis of nine candidate geneenzyme systems. Two strains resistant to benzimidazoles, two multidrug-resistant strains, and three strains susceptible to anthelmintics isolated from three continents were examined by isoelectric focusing. Two enzymes (mannose phosphate isomerase and peptidase-D) had polymorphic patterns. The peptidase-D zymograms indicated an association with the selection for resistance. Susceptible isolates gave more complex patterns due to the formation of a heterodimer controlled by the two active loci, whereas in resistant isolates, only a single locus with one electromorph was responsible for the profiles. A possible link between dipeptidases and the acquisition of resistance through the turnover of proteinrich collagen, and changes in membrane-associated genes that influence drug efflux, are discussed.

Evolutionary programmed development as the basis of Darwinian selection: A review

The sources of biological variation are numerous and versatile. The basic problem is to explain how this huge potential variation could be limited and reduced to adaptive combinations of allelogenes and characters. It has been estimated that, in a population of Drosophila melanogaster with a few thousands of individuals, the number of existing genotypes for a metabolic system controlled by 8-10 polymorphic loci, would not exceed more than 0.5% of possible combinations of genes. Based on individual allozyme analysis of such a system in 400 flies, less than 1 pro-mile of possible combinations of three largest chromosomes of this species could be present in spermatozoa of an adult male, before they enter a competition to produce viable zygotes. Such adaptive combinations are targets of natural selection, realized through a restricted number of developmental (metabolic) programmes, being also the units of inheritance. The basic role in evolutionary development of such systems have intrinsic factors, i.e., the rules of auto-synthesis of well established programmes, directing a restrictive variation of adaptive variants with which Darwinian selection can operate.