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Species conservation strategies Leucaena salvadorensis: genetic variation and conservation David Boshier
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NoPopulation, Country # trees in population 1Nueva Esparta, El Salvador 16 2San Antonio, Honduras 224 3Rio Nacaome, Honduras 120 4La Garita, Honduras 500 5La Galera, Honduras 181 6Calaire, Honduras 700 7Charco Verde, Honduras 79 8San Juan Limay, Nicaragua>1000 2 © CE Hughes
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Nueva Esparta El Salvador 3 © DH Boshier
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Calaire Honduras 4 © DH Boshier
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San Antonio Honduras Rio Nacaome Honduras 5 © DH Boshier
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6 © CE Hughes
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L. leucocephala self compatible 7 © CE Hughes L. salvadorensis self incompatible
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Conservation alternatives preservation of actual diversity conservation of evolutionary potential mantain options for future generations, while satisfying present needs 9
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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 refers to effective population size (N e ) rather than survey numbers (N) – so may need many more! in trees N e smaller than N due to: overlapping generations, dioecy, asynchronous flowering, fecundity differences between individuals 11
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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 12
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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 13
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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 14 © RBG Kew
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useful, but resources limit application to few species (usually commercial) last gasp holding for highly endangered species complimentary to other approaches Conservation of biodiversity ex situ: methods and limitations 15
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a large number of individuals of many species have long ago ceased being ecologically (and evolutionarily) reproductive; they flower but set no seed, or if they set seed, the seedlings never lead to recruitment of adults. 16 © DH Boshier These are the living dead Janzen 1986
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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) Circa situm - conservation within altered agricultural landscapes, within natural distribution 17
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Conservation of biodiversity in practice: circa situm as a necessity? Majority of conservation in situ outside of reserves emphasises: –trees outside of forests –role of indigenous/local communities –role of forest and land administrators –compatibility between resource management systems and conservation objectives 18
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Conservation of alleles common - rare what proportion? widespread - localisedwhat scale? widespread localised commoneasykey rare (<0.05)sample sizeluck 19
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Widespread vs locally common alleles frequency Pop 1234 Allelea0.5000.3200.4500.550 b 0.250 0.0300.0500.050 c0.2300.4000.4500.350 d0.020 0.250 0.0500.050 20
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Figure 2. Genetic similarities (Nei unbiased genetic distance) between L. salvadorensis populations 21
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Table 4. Gene flow (Nm - number of migrants per generation) below shaded boxes and geographic distance (in km) above shaded boxes between L. salvadorensis populations (details in Table 1). Correlation between gene flow and geographic distance: r = - 0.17 Figure 3. Relationship between gene flow between populations (Nm – number of migrants per generation) and geographic distance (km); based on data from Table 4 22
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Leucaena salvadorensis Conservation strategies – four groups El Salvador (country specific strategy) Honduras (country specific strategy) Nicaragua (country specific strategy) FAO (international perspective) 23
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Leucaena salvadorensis each group summarize on wall chart paper or PowerPoint Remember need a conservation objective prioritise actions – resources are limited list the localised but common alleles? 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? 24
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