Paraphyly of organelle DNAs in Cycas Sect. Asiorientales due to ancient ancestral polymorphisms

<p>Abstract</p> <p>Background</p> <p>This study addresses the apportionment of genetic diversity between <it>Cycas revoluta </it>and <it>C. taitungensis</it>, species that constitute the section <it>Asiorientales </it>and represent a unique, basal lineage of the Laurasian genus <it>Cycas</it>. Fossil evidence indicates divergence of the section from the rest of <it>Cycas </it>at least 30 million years ago. Geographically, <it>C. taitungensis </it>is limited to Taiwan whereas <it>C. revoluta </it>is found in the Ryukyu Archipelago and on mainland China.</p> <p>Results</p> <p>The phylogenies of ribosomal ITS region of mtDNA and the intergenic spacer between <it>atp</it>B and <it>rbc</it>L genes of cpDNA were reconstructed. Phylogenetic analyses revealed paraphyly of both loci in the two species and also in the section <it>Asiorientales</it>. The lack of reciprocal monophyly between these long isolated sections is likely due to persistent shared ancestral polymorphisms. Molecular dating estimated that mt- and cp DNA lineages coalesced to the most recent common ancestors (TMRCA) about 327 (mt) and 204 MYA (cp), corresponding with the divergence of cycad sections in the Mesozoic.</p> <p>Conclusion</p> <p>Fates of newly derived mutations of cycads follow Klopfstein et al.'s surfing model where the majority of new mutations do not spread geographically and remain at low frequencies or are eventually lost by genetic drift. Only successful 'surfing mutations' reach very high frequencies and occupy a large portion of a species range. These mutations exist as dominant cytotypes across populations and species. Geographical subdivision is lacking in both species, even though recurrent gene flow by both pollen and seed is severely limited. In total, the contrasting levels between historical and ongoing gene flow, large population sizes, a long lifespan, and slow mutation rates in both organelle DNAs have all likely contributed to the unusually long duration of paraphyly in cycads.</p

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千葉医学雑誌57-

Perceived conflict among Wisconsin superintendents and its relationship to selected factors

The pressures under which superintendents must administer and the national media attention given to conflicts within the school setting prompted this study of conflict in the superintendency. The purpose of the study was to examine the conflict reported by Wisconsin superintendents and to determine if it had any relationship to the superintendents\u27 leadership styles, conflict resolution styles, experience as district administrators, self-reported level of success, and enrollment of the district. Data for the study were obtained through a survey mailed to selected Wisconsin K-12 superintendents the summer of 1987. Results of the survey and subsequent data analyses indicated that Wisconsin superintendents predominantly believed themselves to be team administrators. Their usual method of dealing with conflict was to confront it to work for reasonable solutions, rather than using forcing or smoothing techniques. The areas of their positions which produced the most conflict for superintendents included administration of negotiated agreements, time requirements of the job, fulfilling state, federal, and court requirements, and special interest groups. These areas caused moderate to large amounts of conflict for the superintendents. Areas accounting for the smallest amount of conflict included relations with private or parochial schools, establishment or change of attendance boundaries, cultural diversity within the district, relations with the press/media, student discipline policy development, and transportation services. The study was unable to analyze the relationship between leadership style, conflict resolution style, and the conflict perceived because of skewed returns, and it found no significant relationship between the enrollment of the district, the experience of the superintendent, or the superintendent\u27s feeling of success with the conflict perceived. The researcher recommended that prospective superintendents develop a repertoire of conflict resolution skills, learn to foster change rather than fight it, and try to view conflict as a healthy opportunity for growth within the school setting

Ribosomal DNA Variation within and among Plant Populations

Volume: 75Start Page: 1207End Page: 121

Bayesian All Gaps Phylogeny

MrBayes phylogeny of plastome alignment trimmed with the 'All Gaps' option in Gblock

BEAST Input File

Input XML file for each of 5 BEAST runs 100 million generations each