1.1 leucaena salvadorensis_teachers_presentation
DESCRIPTION
Forest Genetic Resources is a new training guide from Bioversity International. This presentation is from Module One - Species Genetic Conservation and relates to Case study 1.1, Leucaena salvadorensis: genetic variation and conservation. To read more about the training guide and download materials, visit: http://old.bioversityinternational.org/fgr_training_guide/homepage.htmlTRANSCRIPT
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Species conservation strategies
Leucaena salvadorensis: genetic variation and conservationDavid Boshier
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No Population, Country# trees in population
1 Nueva Esparta, El Salvador 16
2 San Antonio, Honduras 224
3 Rio Nacaome, Honduras 120
4 La Garita, Honduras 500
5 La Galera, Honduras 181
6 Calaire, Honduras 700
7 Charco Verde, Honduras 79
8 San Juan Limay, Nicaragua >1000
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© CE Hughes
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Nueva Esparta El Salvador
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© DH Boshier
© DH Boshier
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Calaire Honduras
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© DH Boshier © DH Boshier
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San AntonioHonduras
Rio NacaomeHonduras
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© DH Boshier
© DH Boshier
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© CE Hughes
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L. leucocephala self compatible
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© CE Hughes© CE Hughes
L. salvadorensisself incompatible
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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 refers to effective population size (Ne) rather than survey numbers (N) – so may need many more! in trees Ne 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 sufficient13
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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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© RBG Kew © 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
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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
© DH Boshier
These are the living deadJanzen 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
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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
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Conservation of alleles
common - rare what proportion?
widespread - localised what scale?
widespread localised
common easy key
rare (<0.05) sample size luck
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Widespread vs locally common alleles
frequency Pop 1 2 3 4
Allele a 0.500 0.320 0.450 0.550
b 0.250 0.030 0.050 0.050
c 0.230 0.400 0.450 0.350
d 0.020 0.250 0.050 0.050
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Figure 2. Genetic similarities (Nei unbiased genetic distance) between L. salvadorensispopulations
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Table 4. Gene flow (Nm - number of migrants per generation) below black diagonal and geographic distance (in km) above black diagonal 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
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Leucaena salvadorensis
Conservation strategies – four groupsEl Salvador (country specific strategy)
Honduras (country specific strategy)
Nicaragua (country specific strategy)
FAO (international perspective)23
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Leucaena salvadorensiseach group summarise on wall chart paper
Remember need a conservation objectiveprioritise 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?
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