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Title: Reproductive biology of some Malaysian dipterocarps
Author: Tuck, Chan Hung
ISNI:       0000 0001 3526 7109
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 1977
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This study of the reproductive biology of some emergent species - in the family Dipterocarpaceae forms part of the collaborative research programme between the University of Aberdeen and the University of Malaya on the reproductive biology of tropical rain forest tree species. It is intended that such a study will contribute to a better understanding of the mode of speciation prevalent among rain forest trees which has led to the diversity of species in our present day rain forest. General flowerings of dipterocarps are intense involving nearly all species. Blooming is copious and markedly synchronized for a given species. Among closely related species, flowering is staggered, though with some amount of overlapping. Within Shorea section Muticae, flowers are similar in morphology with low pollen production and sickly sweet scent. Their characteristic floral morphology was shown to be well adapted for thrip pollination. There is a high incidence of self-incompatibility among most species studied. Of all species studied, only Dipterocarpus oblongifolius is self-compatible. During a general flowering, mortality of buds and flowers is partially due to predation. The major cause of mortality during this stage is nevertheless caused by defective pollination. Despite disparity in flowering times among species in the section Muticae, mature fruit fall is concurrent. Fruit production in S. leprosula is variable among individuals comprising a clump but nevertheless is much greater than that produced by isolated .individuals. It is suggested that it is these clumps which maintain high 'reproductive pressures' and are the main breeding groups. Fruit dispersal in dipterocarps is inefficient and the demonstrated clumped distributional pattern seems therefore to be due to poor fruit dispersal. There is 110 consistent correlation of survival during seed germination, seedling establishment and after successful establishment with initial seed density or distance from the tree butt. Seedling and sapling mortality in S. leprosula is extremely high for about the first 20 years and the presence of gaps in the canopy largely determine their survival though other factors may play a role. For the following 30 years mortality rate appears to be insignificant but increases again thereafter. Leaf morphological studies on 55 adult individuals of S, leprosula showed significant heterogeneity that is independent of edaphic influences. Regression analysis of leaf morphological variation with between-tree distance showed, significant linear correlation, It is inferred that gene exchange is restricted, Phytogeographical evidence suggests -that speciation among dipterocarps occurs after initial isolation of breeding populations. Evidence presented here is largely compatible with this view and suggestion that this is enhanced by the ineffectual means of pollen and fruit dispersal.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available