Morphological and genetic variation of Eusideroxylon zwageri Teijsm. & Binn. (Borneo ironwood) in Sarawak, Malaysia
Previously, two species were recognized as Borneo Ironwood, Eusideroxylon zwageri and E. melagangai. However, study revealed that E. melagangai is belonging to a new genus called Potoxylon. This confusion is due to the close morphological resemblance between both species. Borneo Ironwood has hig...
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| Format: | Thesis |
| Language: | English |
| Published: |
2020
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/90719/1/FS%202020%2030%20IR.pdf |
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| Summary: | Previously, two species were recognized as Borneo Ironwood,
Eusideroxylon zwageri and E. melagangai. However, study revealed that E.
melagangai is belonging to a new genus called Potoxylon. This confusion is
due to the close morphological resemblance between both species. Borneo
Ironwood has high demand and high market value because of its valuable
and durable timber, which has put its number at risk of illegal logging. In
addition to threats from illegal logging, the slow seed germination process
delays their natural regeneration in the forest. It may take up to six months
in their natural environment to germinate. Other than that, poor genetic
matching of planting material to the planting site or using seed from small,
inbred populations can result, for instance, in reducing growth, reproductive
output, the ability to resist pests and capacity to adapt to environmental
variation. In this project, two sampling areas were chosen (i) Nirwana
Rehabilitation Forest (NRF), UPM Bintulu Campus, and (ii) fragmented
area in Tatau, Bintulu, Sarawak. The aims for this study were to document
morphological features of E. zwageri and to recognize their varieties by
using conventional method based on the macro-morphology characters
and to support the outcome with cladistics analysis. Subsequently, four
microsatellite markers were used to analyse E. zwageri genetic variation
and their clustering to the varieties based on allelic data. In addition, the
identification of fungi isolated from the fruits of E. zwageri was also
conducted. Three varieties of E. zwageri were identified namely; zwageri,
grandis, and exilis. These varieties were recognized based on the seed,
bark and leaves traits and supported with cladistics analysis and allelic data.
Meanwhile, genetic study shown that 20.1% of total genetic variation
corresponded to differences between populations while 79.9% was
attributed by differences between individuals. The Tatau (Ho = 0.399; He = 0.563) population was observed to have relatively lower genetic diversity
compared to NRF (Ho = 0.659; He = 0.739) area based on the observed
(Ho) and expected (He) heterozygosity value; and both areas shown a
deficiency of heterozygosity indicated by positive FIS value (Tatau = 0.054;
NRF = 0.165) that suggested the population undergoing inbreeding event.
Furthermore, study on fungi diversity isolated from E. zwageri fruits
identified fungi from nine taxa from Ascomycota phylum namely;
Annulohypoxylon nites, A. viridistratum, Daldinia eschscholtzii, Hypoxylon
investiens, Lasiodiplodia theobromae, Trichoderma asperellum, T. crassum,
T. spirale, and T. virens. This data will be useful for future understanding in
fungi involvement in rooted seed in E. zwageri species. It is hope that the
results from this study will be used as baseline data in an effort to protect
this vulnerable species. |
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