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Species conservation strategies Talbotiella gentii: genetic variation and conservation David Boshier, Daniel Dompreh and Mike Swaine
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100km MSD ME WE D SD SM Krobo Worobong Bandai Hills Yongwa Sapawsu Forest Reserves in Ghana and distribution of Talbotiella gentii Dompreh, 2008
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Records of Talbotiella populations in Ghana Red dots = Extant populations, Yellow dots = Extinct populations.
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Sapawsu
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Yogaga Bandai
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Yongwa
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Talbotiella gentii 15 of 28 populations now extinct Most of those extinct are outside reserves Threats inside and outside reserves from fires, firewood cutting Populations range in size from 2-500 adult trees
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1982 1990 2005 Damage of Talbotiella population at Krobo mountain from fire and fuelwood exploitation over 23 years
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Aburi Botanical Gardens
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Conservation alternatives Preservation of actual diversity Conservation of evolutionary potential Mantain options for future generations, while satisfying present needs
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How big is “big enough”? 50/500 rule (Franklin 1980) 50 - inbreeding depression to acceptable level 500 - sufficient for new variation from mutation to replace that lost by genetic drift effective population size (N e ) more critical than survey numbers (N) - may need 5,000! in trees N e smaller than N due to: overlapping generations, dioecy, asynchronous flowering, fecundity differences between individuals
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Where should we conserve? In situ - reserve system of undisturbed, protected areas within natural distribution (ecosystem based) Ex situ - artificial maintenance of populations outside natural distribution (species based) In situ Ex situ
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Conservation of biodiversity in situ : trees as a paradigm Ideal reserve model Emphasis: large, continuous, protected areas Limitations: location, size, security, biology: –movement of animals –extensive distribution of many species –gene flow between populations –upland, non agricultural areas essential but not sufficient
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Conservation of biodiversity ex situ : methods and limitations Seed banks - problems of regeneration Plantations - changes in gene frequencies, few populations Botanical gardens - deficiencies for gene pool conservation
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Useful, but resources limit application to few species (usually commercial) Last possibility holding for highly endangered species Complementary to other approaches Conservation of biodiversity ex situ : methods and limitations
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Bottleneck genetic drift
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Table 3 Within population genetic variability in Talbotiella gentii, estimated by percentage of polymorphic loci for 83 RAPDs polymorphic bands (8 primers) PopulationPopulation sizeNo. of samples% polymorphic loci Abiriwapong Botriansa Yongwa Nayom Doorkper Sapawsu Hospital Chalet Ajena Kuwere Krobo Yogoga Hotel Boobohene Oseikrom Senkyeso Kwame Addo >100 2 >100 39 21 >50 2 >50 16 >20 11 27 20 6 2 3 16 2 13 5 8 2 8 6 4 8 5 2 16.3 2.1 13.6 5.2 3.9 8.1 0.8 8.4 4.8 3.1 7.7 7.9 4.4 2.1
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Figure 3. Effect of geographic distance of pollen source on initial fruit set in Talbotiella gentii
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Talbotiella gentii each group summarize on wall chart paper or PowerPoint Remember - need a conservation objective - prioritize actions – resources are limited list problems by type - genetic, which pops. too small? which are different? - other types of problems which conservation methods - in situ, ex situ, circa situm? who? will do, what? where? how will you pay for it?
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