Development of caryological and molecular-genetic investigations of wetland and dryland populations of conifers

Aim. On the basis of studies which carried out by various authors, regularities of karyotypic and genetic divergence of populations of conifers growing in wetlands and dry lands are analyzed. Methods. The karyological and molecular-genetic methods of analysis are used. Results. Data are obtained on possible ways of evolution of karyotypes, consisting in changes in the number of chromosomes, the size and morphology of chromosomes, the number of secondary constrictions in chromosomes, the spectrum of chromosome rearrangements, and the frequency of their occurrence, distinguishing wetland populations of conifers species from dry land ones. With the help of isozyme markers and markers of nuclear and cytoplasmic genomes differences in the genetic structure of conifers populations from wetlands and dry lands are revealed. Conclusions. The genotypic structure of conifers species in wetlands and dry lands, caused by different vector of natural selection in contrasting ecological conditions of growth, differs significantly, and their karyotypic and genetic differentiation corresponds to the level of populations and groups of populations. Keywords: populations of conifers, wetlands, dry lands, karyological and molecular-genetic markers.

Chromosome morphology in Gilbert's potoroo, Potorous gilbertii (Marsupialia : Potoroidae)

Chromosome morphology was examined for male and female Gilbert’s potoroo, Potorous gilbertii, to infer taxonomic and evolutionary relationships among the extant taxa within the genus Potorous. P. gilbertii has the same number of chromosomes as P. tridactylus, 2n = 12,13. Giemsa-banding patterns were very similar in P. gilbertii and P. tridactylus; however, differences were noted between the sex chromosomes. Given that the relationships among extant Potorous are unresolved, we mapped karyotypes onto two alternative phylogenies to suggest methods of karyotype evolution within this group. Karyotypes and molecular-based information from the now ‘presumed extinct’ P. platyops or sequencing of multiple gene regions for phylogenetic analysis within the Potoroidae would provide valuable information for resolving the issue of rooting, and hence drawing conclusions on the evolution of karyotypes within this group.

On the cytology of two species of Necrobia (Oliv.) (Coleoptera: Cleridae)

The karyology of Necrobia ruficollis F. and Necrobia rufipes De Geer was investigated. The male karyotype of the species is 18♀:8+Xyp. Details of structure and behaviour of chromosomes during cell division are presented. Variations in the morphology of chromosomes in Necrobia species and trends in the evolution of karyotypes in the Cleridae are discussed.Key words: Cleridae, karyotype, sex chromosome mechanism, polyphaga, pericentric inversion.

The karyotes of some Australian Rodents (Rodentia : Muridae)

The number and morphology of the chromosomes of 11 species of Australian rodents have been described. It is suggested that Rattus lutreolus (2n = 42) is derived from an ancestor closely related to R. norvegicus (2n = 42) and that the former gave rise, in Australia, to R. fuscipes (2n = 38). R. fuscipes then gave rise to R. greyi (2n = 38) and R. assimilis (2n = 38) with both of which it is conspecific. Pseudomys minnie (2n = 48) and two species of Leggadina (2n = 48) have very similar karyotypes which differ from the karyotypes of two species of Notomys (2n = 48). The latter have apparently identical chromosomes. Within the Pseudomys group, marked changes in the heteromorphic pair of chromosomes have been involved in the evolution of karyotypes.