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Species conservation strategies
Talbotiella gentii: genetic variation and conservation
David Boshier, Daniel Dompreh and Mike Swaine
100km
MSD
ME
WE
D SD
SM
Krobo
Worobong
Bandai Hills
Yongwa
Sapawsu
Forest Reserves in Ghana and distribution of Talbotiella gentii
Dompreh, 2008
Records of Talbotiella populations in GhanaRed dots = Extant populations, Yellow dots = Extinct populations.
Talbotiella gentii
15 of 28 populationsnow extinct
Most of those extinctare outside reserves
Threats inside and outside reserves from fires, firewood cutting
Populations range in size from 2-500 adult trees
1982
1990
2005
Damage of Talbotiella population at Krobo mountain from fire and fuelwood exploitation over 23 years
Conservation alternatives
• Preservation of actual diversity
• Conservation of evolutionary potential
• Mantain options for future generations, while satisfying present needs
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 (Ne) more critical than survey numbers (N) - may need 5,000!
• in trees Ne smaller than N due to: overlapping generations, dioecy, asynchronous flowering, fecundity differences between individuals
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
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
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
• 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
Table 3 Within population genetic variability in Talbotiella gentii, estimated by percentage of polymorphic loci for 83 RAPDs polymorphic bands (8 primers)Population Population size No. of samples % polymorphic loci
AbiriwapongBotriansaYongwaNayomDoorkperSapawsuHospitalChaletAjena KuwereKroboYogoga HotelBooboheneOseikromSenkyesoKwame Addo
>1002
>1003921
>502
>50>5016
>20112720623
162
1355828648552222
16.32.1
13.65.23.98.10.88.44.83.17.77.94.42.12.12.12.1
Talbotiella gentiieach 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?