Genetic diversity and taxonomy in soil-dwelling insects: the genus Orchesella

Article Abstract:

Genetic characteristics of four species of Orchesella were evaluated to determine a genetic basis for taxonomy. The four species were found to be genetically distinct on the basis of allele frequency distribution and allozyme variability. Genetic divergence analysis showed very high values, suggesting that divergence took place in the distant past. O. villosa was studied more intensively to determine the rate of gene flow between geographically distinct populations. The two methods used gave conflicting results. O. villosa was thought to form two populations, inland and coastal, which might form the basis for subspecies differentiation.

Genetic aspects, Identification and classification, Insects, Taxonomy (Biology), Biology, Collembola, Springtails

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Spermatogenesis and synaptonemal complexes of hybrid Petrogale (marsupialia)

Article Abstract:

An analysis of fertility in four different rock wallaby hybrids reveals that the extent of chromosomal heterozygosity depends on the disruption of spermatogenesis and the extent of asynapsis and XY-autosome associations. The formation of synaptonemal complexes is comparable to that of G-banded karyotypes. The chromosomes, responsible for the centric shifts in one hybrid, form heteropycnotic masses instead of pairing. Linkage between the nonpairing X and Y chromosomes and an array of patterns of abnormalities at the ultrastructural level occurs in spermiogenesis of hybrid marsupials.

Analysis, Marsupialia, Marsupials, Heterozygosis, Heterozygote

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Aberrant spermatogenesis and the peculiar mechanism of sex determination in symphypleonan collembola

Article Abstract:

The peculiar spermatogenesis in the collembolan species Sminthurus viridus and Allacma fusca is described using light and electron microscopy.

Usage, Electron microscopy

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