Browsing by Author "Mihretie, Ziyin"

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    Chromosome Study of the Common Mole Rat (Tachyoryctes splendens) from Different Localities in Ethiopia
    (Addis Ababa University, 2005-06) Mihretie, Ziyin; Dagne, Kifle (PhD)
    The common mole rat, Tachyoryctes splendens, belongs to family Rhizomyidae or Muridae (Mammalia; Rodentia). Somatic chromosomes of the species were studied from 9 localities in Ethiopia (Mugo, Masha, Bure, Ziway, Asebe Teferi, Alemaya, Entoto, Sebeta and Debre Sina) using the standard Giemsa staining and C-banding techniques. Six different karyotypic forms were found. These variations were revealed as differences in chromosome morphology, autosomal fundamental number, amount and distribution of heterochromatin. However, there was no variation in diploid chromosome number and specimens from all the localities had 2n=48. The six karyotypic forms had the following karyotypic formulae: Mugo, Masha and Bure (12m + 10st + 26a), Debre Sina (10m + 8st + 30a), Ziway (8m + 12st + 28a), Asebe Teferi (8m + 4st + 36a), Alemaya (8m + 6st + 34a), and Entoto and Sebeta (7m + 1 sm + 2st + 38a). C-banding revealed that, in addition to the Y-chromosome (except in Entoto), 12, 12, 36, 4, 6, 4, 4 autosomes in Mugo, Masha, Ziway, Asebe Teferi, Alemaya, Entoto and Sebeta were C-positives, respectively. The telomeric region of the long arm of the X-chromosome was also C-positive in animals from Entoto and Sebeta. The present study did not confirm the earlier suggestions that the number of biarmed chromosomes of T. splendens decreases with the increase in aridity and the number of heterochromatic arms may exhibit an altitude gradient. We recommend further studies like Gbanding, zoogeographical, physiological and hybridization studies on T. splendens from different parts of the distribution range of the species so that the results could supply information to reveal factors associated with the existing variations, and to draw a valid conclusion that could be used in clearing the taxonomic uncertainties in this animal. Key words/ Phrases: Tachyoryctes splendens, chromosome, karyotype, C-banding, Ethiopia
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    Morphological and Molecular Diversity, Phylogeography and Ethnobotany of Pnmus Il/ricana (Hook. f.) Kalkman in Ethiopia
    (Addis Ababa Universty, 2014-06) Mihretie, Ziyin
    This dissertation reports diversity, phylogeography and ethnobotany of Prunus africana (Hook. f.) Kalkman in Ethiopia. P. africana is an economically important, but endangered tree species of Africa. Five quantitative morphological traits were studied in situ on 21 natural populations of P. aji'icana over its distribution range in Ethiopia, and the following mean values were found: total height (l9.3m), bole height (7.4m), diameter at breast height (70.2cm), bark thickness (20.3ulIn), and fresh bark mass (I 59.6kg). Al"lOYA based ou the five traits revealed that there was significant variation among populations (P < 0.001), which could be due to environmental andlor genetic or age structure differences. Pearson's correlation analysis revealed significant positive correlations among all traits (except bole height vs. bark thickness) (P < 0.0 I). Furthermore, all traits (except bark thickness) showed significant negative correlations with altitude (P < 0.05). Six nSSRs and five cpSSRs were used to study molecular genetic diversity and structure of the 21 P. aji'icana populations. A total of 89 nSSR and 14 cpSSR alleles, and 16 chloroplast haplotypes were found. The study showed that P. [!!i'icana in Ethiopia maintains high levels of diversity in both nSSR (Hr = 0.725) and cpSSRs (hI' = 0.703). AMOYA revealed that most (88.05%) of the nuclear genetic variation occurs within populations; whereas nearly half (47.8%) of chloroplast genetic variation occurs among populations. There was moderate nuclear (FsT = 0.122) and high chloroplast (OST = 0.478) genetic differentiation among populations (P < 0.00 I). Distance-based clustering (peoA and UPGMA) and individual-based population assignment methods as well as comparison of observed and permuted differentiation indices revealed geographic pattern for nSSR diversity, but no geographic pattern for cpSSR diversity, which could be due to differences in the effect of genetic drift and/or the mechanism of gcne flow between cpDNA and nDNA. However, Mantel test indicated signiticant positive correlation between geographic and genetic distances for both nSSR (Rxy = 0.126) and cpSSR (Ib,:y = 0.107) (P = 0.00 I). The ethnobotanic study confirmed the multipurpose character of P. {{fi'icana, and six major use categories (medicinal, construction and carpentry, fuel/firewood, beverage preparation, apiculture, and traditional rituals) were determined for the species. Significant genetic differentiation in more than 95% of the population pairs suggests that almost all the populations deserve conservation, but as there are often limitations of resources to conserve such a large number of populations, prioritization may be needed. Thus, based on a weighted-score population prioritization matrix that integrates genetic, morphological, conservation status, and ethnobotanic criteria; Kuni, Jimma, and Assela are the top three priority populations for conservation of the species.