Browsing by Author "NIGUSSU BEGASHAW ABATE"

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    GENETIC CONSIDERATIONS AND MOLECULAR TOOLS FOR FOREST CONSERVATION AND RESTORATION: EMPHASIZING Afrocarpus gracilior (Pilg.) C. N. Page IN SOUTHERN ETHIOPIA
    (Hawassa University College of Agriculture, 2025) NIGUSSU BEGASHAW ABATE
    Large-scale tree planting initiatives and ambitious global forest restoration commitments aim to mitigate the impacts of deforestation. Ensuring the long-term success of these efforts requires integrating genetic principles into restoration practices. This study aims to enhance forest conservation and restoration by generating molecular genetic insights and tools, using Afrocarpus gracilior, a native dioecious conifer, as a case study. Specifically, it evaluates the extent to which genetic principles are considered in species selection and seed procurement, investigates the genetic consequences of population fragmentation, assesses inbreeding depression, and develops molecular markers for early sex identification. To achieve these objectives, the study combined a survey of tree nurseries and seed vendors with genetic analyses using DArTseq-generated SNPs to assess genetic diversity and population differentiation. Additionally, in vitro germination and early progeny growth experiments were conducted to evaluate inbreeding depression, while RAPD markers and bulk-segregant analysis were used for sex identification. Assessment of genetic considerations in forest restoration revealed that crucial guidelines are frequently overlooked in species selection and seed procurement, with exotic species dominating while native species remain underrepresented. Seed collection practices often neglect essential measures for preserving genetic diversity, heightening the risk of inbreeding and reducing adaptive potential. Notably, 84% of seed collectors sourced seeds indiscriminately, 87% of nurseries received seeds without passport data, 97% of seed collectors failed to meet the minimum required number of mother trees per collection event, and 88% ignored recommended spacing between selected mother trees. Genetic diversity analysis of A. gracilior populations showed overall low genetic diversity (Hₑ < 0.1), with progeny cohorts exhibiting even lower diversity than adults. Progeny from isolated or few mother trees had the lowest genetic diversity, indicating heightened genetic drift and inbreeding. In contrast, sacred forests and larger remnant patches harbored relatively higher genetic diversity, indicating their importance for in situ conservation. Further assessment of inbreeding depression in fragmented populations revealed significant reductions in progeny fitness, including 53% lower germination rates, 33% reduced acclimatization, 30% and 41% slower growth in diameter and height, respectively, and a 62% increase in leaf scorch. Screening for sex-linked markers identified OPD-18 (5’-GAGAGCCAAC-3’) as a 600 bp male-specific RAPD marker, providing a foundation for early sex determination in A. gracilior. xix The results highlight the critical role of genetic considerations in successful forest restoration, yet current practices often overlook these principles, increasing the risk of inbreeding and loss of adaptive potential. Very low genetic diversity was recorded across all fragmented populations of A. gracilior, with progeny from isolated or few mother trees exhibiting the lowest genetic diversity and significantly reduced fitness. These findings indicate increased genetic erosion, drift, and inbreeding depression, jeopardizing the species’ long-term survival. Recommendations include establishing and enforcing policies that promote the use of native species and genetic standards in seed procurement; sourcing seeds from diverse, larger populations; prioritizing in situ conservation of sacred sites; and further developing robust molecular markers to improve the reliability of early-stage sex identification in the dioecious A. gracilior. Implementing these measures would enhance the long-term success of restoration initiatives, fostering resilient forest ecosystems that support biodiversity conservation and sustainable land management.