IMPACTS OF LOGGING ON GENETIC DIVERSITY OF TWO DIPTEROCARPS WITH CONTRASTING BREEDING SYSTEMS

1. Case study 2 IMPACTS OF LOGGING ON GENETIC DIVERSITY OF TWO DIPTEROCARPS WITH CONTRASTING BREEDING SYSTEMS

2. Introduction • Levels of genetic diversity can be quantified using various parameters: • Allelic richness (mean number of alleles per locus or effective number of alleles per locus) • Gene diversity (heterozygosity) • Etc

3. Therefore Logging activities should maintain genetic diversity because it is required for a species for long-term evolutionary adaptation and short-term fitness In theory Reduced heterozygosity can result in decrease of population growth due to inbreeding depression (Charlesworth and Charlesworth, 1987). Allelic richness could contribute to population growth through its effect on evolutionary potential, or the ability of a species to respond to changes in its selective environment (Koehn and Hilbish, 1987).

4. Species selection • Two dipterocarp species with contrasting breeding systems • Shorea leprosula (predominantly outcrossed) • Shorea ovalis (apomictic; tetraploid)

5. S. leprosula

6. S. leprosula (domatia)

7. S. leprosula (flowers)

8. S. leprosula (seeds)

9. S. ovalis (fruiting tree)

10. S. ovalis (dry leaves)

11. S. ovalis (stipule)

12. S. ovalis (seeds)

13. Gene flow Demograhic structure logged Next mature crop logged In theory Demographic structure (levels of genetic diversity at various developmental stages) and gene flow from adjacent populations can compensate the possible genetic erosion due to logging Logging events involve extraction of mature trees Next crop

14. Pollen & seed Seed only Outcrossed species Apomictic species S. leprosula S. ovalis Seed dispersal is mainly by gravity – short distance

15. Question Does S. ovalis (apomictic) more susceptible to negative impacts of logging than S. leprosula (outcrossed)? Therefore Genetic erosion of S. ovalis (apomictic) after logging is unlikely to be compensated by gene flow from adjacent populations

16. Study sites NS = Natural site LS = Logged-over site Pasoh Forest Reserve LS = Logged-over stand (logged in 1955) Intensity of logging – 13.5% reduction of basal area (trees >10 cm dbh) with large-diameter trees showing the largest reduction (Lee et al. 2002: Biological Conservation 104: 107-118)

17. Sample collection

18. SSRs analysis (Shc01, Shc02, Shc03, Shc04, Shc07, Shc09 & Shc17; Ujino et al. 1998) Data analysis (Aa & He) DNA extraction

19. S. leprosula Inverse J distribution • Natural – Large tree > pole-sized tree ≈ seedling Predominantly outcrossing species • Logged - Reduction of genetic diversity at all the three stages • Elimination of alleles with low frequency (rare alleles)

20. S. ovalis Inverse J distribution • Natural – Large tree ≈ pole-sized tree ≈ seedling Apomictic species • Genetic diversity maintained after logging • No obvious reduction of Aa at all the three stages

21. For apomictic species (S. ovalis), maintaining of genetic diversity can be due to apomictic mechanisms and tetrasomic inheritance that maintained genetic diversity at pole-sized trees and seedlings For predominantly outcrossed species (S. leprosula), loss of genetic diversity in logged-over stand still prevailed even after 50 years of regeneration. This might indicate that the population dynamic processes (i.e., gene flow) were unable to restore the loss of genetic diversity Instead of relying on gene flow to restore the loss of genetic diversity, logging activities on S. leprosula should designed in a way that the current levels of genetic diversity can be maintained even after logging

22. Simulated-removal of individual based on cutting limit (dbh) to maintain maximum levels of genetic diversity • Using the 154 large S. leprosula from Natural Site • Simulated-removal of individuals based on dbh (cm): >100, >95, >90, >85, >80, >75,…..>35 • Also tested for the prescriptions of: • Malayan Uniform System (MUS) - removing of trees >45 cm dbh • Selective Management System (SMS) - removing of trees >50 cm dbh

23. 100% 95% SMS MUS

24. S. leprosula (large trees) 35 m BIG 0.15 0.1 0.05 I 0 Moran's -0.05 -0.1 Ng et al. 2004: Molecular Ecology 13: 657-669 -0.15 1 2 3 4 5 6 7 8 9 Distance class Simulated-removal of individual at random versus in clump It is postulated that loss of genetic diversity will be more rigorous if logging activities are anticipated to extracts trees in clump rather than random

25. Simulated-removal of individual at random • Using random number generator • Individuals were identified and removed randomly

26. Resampling 3 Resampling 2 Resampling 1 • Simulated-removal of individual in clump • Using random number generator • A focal individual was selected • Based on XY coordinates, other nearest individuals were selected and removed in clump

27. Random Clump Removal of <12% individuals at random will be able to maintain ≈100% alleles 14.6%

28. Conclusion: Does S. ovalis (apomictic) more susceptible to negative impacts of logging than S. leprosula (outcrossed)? No, apomictic mechanisms and tetrasomic inheritance of S. ovalis maintain genetic diversity at pole-sized tree and seedling Simulated-removal of individual based on cutting limit To conserve 100% of alleles, the tolerable cutting limits > 85 cm dbh (It is important, however, to keep in mind that this estimate might be species and even population specific) Simulated-removal of individual at random versus in clump Support the postulation that loss of genetic diversity will be more rigorous if logging activities are anticipated to extracts trees in clump rather than random

29. Thank You