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C K Yoon

Publications and source records attributed to C K Yoon.

5 recordsLinked to original sources
PubMed1994

Molecular evolution of the period gene in Drosophila athabasca.

We measured nucleotide variability within and between the three semispecies of the Drosophila athabasca complex, at the period (per) gene by using a polymerase chain reaction-based four-cutter restriction-enzyme analysis. The levels of polymorphism varied considerably between the three semispecies. Our results for per, combined with previous data for X-linked allozymes, suggest that the X chromosome in the western-northern semispecies is less variable than expected under an equilibrium-neutral model. Both the pattern of divergence between the semispecies and a cladistic clustering of per haplotypes support the previously hypothesized grouping of eastern A and eastern B as the two most recently diverged semispecies. A 21-bp in-frame segment in the region of per which shares sequence similarity with the neuronal development gene single minded is deleted in all eastern A and eastern B flies examined but is present in all of the western-northern flies and all other published per sequences. Despite these hints that there may be significant differences at the per gene between the semispecies, especially the western-northern group versus the two eastern groups, there is no compelling evidence that per is involved in the mating song differences between the semispecies.

Animals↗
PubMed1987

Mandibular border positions and their relationships with peripheral joint mobility.

Peripheral joint mobility was assessed in a group of fifty-one dental students using a modification of the Carter and Wilkinson Index. Mandibular border positions were measured both actively and passively with the aid of a millimetre ruler. The purpose of the investigation was to study possible relationships between generalized joint (hyper-)mobility and (hyper-)mobility of the temporomandibular joints. Only a few weak correlations were found between the mandibular border position measurements (active and passive mouth opening, active and passive, left and right, laterotrusions and active protrusion) and the peripheral joint mobility measurements. Differences between the sexes were illustrated in peripheral joint mobility with females showing a greater joint mobility than males, especially when only the passively measured joints were considered. The mandibular border positions were significantly correlated with each other (P less than 0.05-P less than 0.001) for the males, but few and then only weak relationships between these measurements could be found for the females in this group. The concept of temporomandibular joint 'end-feel' in relation to joint mobility is discussed.

Adult↗
PubMedDate not supplied

Mitochondrial DNA variation among the Drosophila athabasca semispecies and Drosophila affinis.

Morphology, allozymes, and levels of postreproductive isolation indicate that the semispecies of Drosophila athabasca are as recently diverged as typical populations within a Drosophila species. However, levels of behavioral isolation, divergence in male mating song, and divergence in X-chromosome inversions suggest a much more ancient divergence. In this article, we have examined mitochondrial DNA restriction site variation within and among the three semispecies. These data support the hypothesis that the three semispecies of Drosophila athabasca are at least as recently diverged as are typical populations within other species of Drosophila. Male mating song, behavioral isolation, and X-chromosome differences thus appear to have evolved very rapidly. In addition, hypothesized phylogenetic relationships of these three semispecies, based on our mtDNA data, are identical to those based on allozymes and chromosomal inversions. According to this phylogeny, recency of ancestry is not well correlated with levels of behavioral isolation, whereas patterns of sympatry and allopatry are. These patterns strongly implicate the action of selection in the rapid evolution of behavioral isolation and X-chromosome gene arrangement.

Animals↗