Wed 02 May 2018: 4.00pm [QE] – Darren Sim on “Phytoplankton-Regulation by Macrophytes in Tropical Lakes”

Department of Biological Sciences, NUS
Qualifying Examination

Phytoplankton-Regulation by Macrophytes in Tropical Lakes

Speaker:             Sim Zong Han Darren (Graduate Student, Dept. of Biological Sciences, NUS)
Date:                   2 May 2018, Wednesday
Time:                   4pm
Venue:                DBS Conference Room (S3 Level 5)
Supervisor:        Asst Prof Darren Yeo Chong Jinn
 

Abstract: – Ecological restoration can be a sustainable strategy to manage nuisance phytoplankton in Singapore reservoirs. Macrophytes are vital for restoring degraded lakes due to their involvement in ecological processes, especially their role in maintaining the clear water stable state in lakes. This is attributed to their ability to regulate phytoplankton communities through a combination of physical and biological mechanisms such as attenuation of wave energy, resource competition, and allelopathy. Allelopathy is suspected to be a major mechanism by which macrophytes inhibit phytoplankton, but current evidence supporting this is inconclusive. Present understanding of lake restoration is largely based on temperate studies, which may have limited transferability to the tropics due to trophic and climatic differences.

This study uses various approaches to investigate the ability of macrophytes to improve the ecological state of turbid tropical lakes. Field mesocosm experiments will be used to evaluate (i) the effects of macrophytes on phytoplankton communities and (ii) the potential restorative capability of macrophytes in a turbid reservoir. Lab experiments will be conducted to evaluate the importance of allelopathy as a mechanism to control phytoplankton and the role of light in influencing its effectiveness. Findings will not only improve our understanding of macrophyte-phytoplankton interactions, but also inform lake management decisions using macrophyte restoration as a sustainable tool to control phytoplankton blooms.

All are welcome

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Thu 26 Apr 2018: 3.00pm [QE] – Pratibha Baveja on “Implication of differential gene flow on species and subspecies integrity of SEA birds”

Department of Biological Sciences, NUS
Qualifying Examination

Implication of Differential Gene Flow on Species and Subspecies Integrity of Birds in South-east Asia

Speaker:             Pratibha Baveja (Graduate Student, Dept. of Biological Sciences, NUS)
Date:                   26 April 2018, Thursday
Time:                   3pm
Venue:                DBS Conference room II (S1, Level 3, mezzanine)
Supervisor:        Asst Prof Rheindt, Frank Erwin
 

Abstract: – Strength of gene flow determines the evolutionary trajectory of a species. Inter-specific gene flow or genetic leakage could threaten the genetic integrity of the species or could sometimes lead to hybrid speciation. Birds of Southeast Asia experience such unusual gene flow dynamics because of the unique evolutionary and human cultural history of the region.

In my thesis, I study: 1) Supertramp gene flow dynamics:  Supertramps are highly dispersive forms found on small islands that are closely related to distinct species on mainland with little overwater gene flow capability. It is suggested that small islands in Southeast Asian archipelago might be inhabited by forms that follow very different gene flow patterns than expected. 2) Introgression in captivity of terminally endangered species with potential for reintroduction into the wild. As human-mediated habitat changes may lead to increased instances of secondary contact between previously isolated taxa, such a study becomes relevant in better understanding of gene flow dynamics in birds of Southeast Asia.

All are welcome

Wed 25 April 2018: 3.00pm [QE] – Louise Neo on “Centers of plant generic endemism in Borneo and their significance for biogeography and conservation”

Department of Biological Sciences, NUS
Qualifying Examination

Centers of plant generic endemism in Borneo and their significance for biogeography and conservation

Speaker:              Louise Neo (Graduate Student, Dept. of Biological Sciences, NUS)
Date:                   25 April 2018, Wednesday
Time:                   3.00pm
Venue:                Seminar Room 2 (S2 Level 4, #04-15)
Supervisor:         Assoc Prof Hugh Tan T W
Co-Supervisor:  Dr Wong Khoon Meng (Principal Researcher, Singapore Botanic Gardens)

 Abstract: – The narrow geographical ranges of endemic plants that make them regionally or globally rare, render them of special interest for biogeographic research and conservation. Endemic genera can be unique evolutionary lineages. Centers of generic endemism, where these are concentrated, can indicate special environments, or could be areas of active speciation or refugia. The highly biodiverse rainforests of Borneo have been a major source of speciation and dispersal for plant lineages in Southeast Asia since the pre-Miocene, but they are hypothesized to be in a refugial state at present and, therefore, highly threatened. Centers of plant generic endemism have never been examined, although they can highlight priority areas for biogeographic research and conservation.

I use a taxonomy-informed approach to gather the known occurrences of the endemic and near-endemic plant genera of Borneo from critically identified herbarium specimens, with the aims of (1) mapping distribution patterns of the genera, (2) identifying centers of generic endemism and their environmental correlates, (3) understanding distribution patterns and centers of generic endemism within the historical biogeography context of Borneo, and (4) assessing conservation exigencies for these genera.

All are welcome

Thu 26 April 2018: 10.00am [QE] – Kenny Chua on “Freshwater fish diversity and ecosystem functioning in Southeast Asia”

Department of Biological Sciences, NUS
Qualifying Examination

Freshwater fish diversity and ecosystem functioning in Southeast Asia

Speaker:    Kenny Chua Wei Jie (Graduate Student, Dept. of Biological Sciences, NUS)
Date:            26 April 2018, Thursday
Time:              10am
Venue:             DBS Conference Room  (S3 Level 5, #05-01)
Supervisor:     Asst Prof Darren Yeo Chong Jinn

Abstract: – The highly diverse ichthyofaunas of Southeast Asian fresh waters are threatened by land-use change, resulting in declines in species richness. Given the ecological importance of freshwater fishes, the loss of their diversity is expected to alter ecosystem functioning—i.e., pools and fluxes of biogeochemical resources—but these potential impacts remain poorly understood in Southeast Asia. To address this knowledge gap, I aim to elucidate the relationship between freshwater fish diversity, ecosystem functioning and land-use change in Southeast Asia.

By characterising and analysing the variation in functional traits of freshwater fishes, my work will investigate mechanistic links between freshwater fish diversity and the ecosystem functions mediated by them. I will also conduct both cross-sectional and longitudinal field studies across Southeast Asia to quantify the impacts of land-use driven fish diversity losses on the functioning of flowing fresh waters in the region. Since ecosystem functions ultimately underpin ecosystem services that are essential for human well-being, knowledge gained from this study will help illuminate the potentially far-reaching and reflexive consequences of anthropogenic biodiversity loss.

All are welcome

Fri 13 Apr 2018: 10.00am [PhD defense] – Muhammad Izuddin Bin Mohamad Rafee on “Conservation of epiphytic orchids in urbanised tropical environments”

PhD Defense Seminar cum Oral Examination

ConservIzuddin.jpgation of epiphytic orchids in urbanised tropical environments

Speaker:       Muhammad Izuddin Bin Mohamad Rafee (Graduate Student Dept. of Biological Sciences, NUS)
Date:             13 April 2018, Friday
Time:             10am
Venue:          DBS Conference  Room (S3 LEVEL 5, #05-01)
Supervisor:   Assoc Prof Edward L. Webb

Abstract – 

“As urban expansion persists, preserving biodiversity becomes progressively difficult. Yet, ex situ methods can facilitate biodiversity conservation in urban spaces. However, species-specific niche requirements—particularly in urbanised environments—remain largely unknown, making ex situ conservation programmes ineffectual. Using native epiphytic orchids as a study system, I assessed two primary ecological barriers to orchid regeneration in urban habitats, namely availability of orchid mycorrhizal fungus / fungi (OMF) as well as the niche requirements of OMF and native orchids.

First, I assessed the availability of OMF on urban trees and the orchid-site suitability of various orchid species by conducting metabarcoding and next-generation sequencing on tree bark and orchid samples. I also identified biophysical factors that influenced OMF presence and richness on urban sites.

Second, I investigated the germination niches—i.e. compatible OMF and suitable biophysical conditions—of four orchid species by conducting orchid mycorrhizal fungal baiting and seed sowing experiments. I then assessed the potential for aboveground orchid seed banks (seed longevity) using seed viability tests on post-experimental, non-germinated seeds.

Third, I evaluated the effectiveness of managed relocation of multiple native orchid species in various urban habitats via long-term planting experiments, as well as identified species post-germination niche requirements that influenced the long-term survival and growth of translocated orchids.

My results indicated that OMF are present on urban trees. However, presence, diversity, and distribution of OMF were primarily constrained by biophysical factors. Urban trees can support germination niches for native epiphytic orchids as well. I also found evidence of seed bank formation on epiphytic microsites. Based on the long-term study, majority of the species showed survival and positive growth. Overall, this thesis demonstrates how species-specific niche requirements can be evaluated / quantified and how the information gained can benefit ex situ, as well as in situ, orchid conservation.”

All are welcome

 

Mon 23 April 2018: 11.00am [QE] – Lionel Ng on “Functional characterisation of coral species for enhancing reef restoration”

Department of Biological Sciences, NUS
Qualifying Examination

Functional characterisation of coral species for enhancing reef restoration

Speaker:              Ng Chin Soon Lionel (Graduate Student, Dept. of Biological Sciences, NUS)
Date:                   23 April 2018, Monday
Time:                   11am
Venue:                DBS Conference room  (S3 Level 5)
Supervisor:        Asst Prof Huang Danwei
Co-Supervisor:  Prof Chou Loke Ming

Abstract: – The global decline of coral reefs has necessitated active management strategies in the form of restoration and rehabilitation. Despite the emphasis on reinstating taxonomic diversity on degraded reefs, there is limited understanding on how such actions and the species used collectively contribute to reef ecosystem functioning. This could be addressed by adopting a trait-based approach to reef restoration, but this is hampered by a general paucity of available information on coral traits.

My thesis focuses on characterising the functional traits of reef stony corals to prioritise species for the rehabilitation of Singapore’s degraded reefs. Broadly, I aim to: 1) establish species distributions across Singapore’s coral habitats, 2) investigate species responses to bleaching, 3) quantify coral growth rate and skeletal density, and 4) examine stakeholder inputs towards reef restoration. The data obtained will be incorporated into a decision-making framework so that relevant and effective restoration strategies can be formulated.

The research is expected to enhance coral reef management in Singapore, and is applicable to other coastal cities seeking to optimise their habitat rehabilitation strategies.

All are welcome

Fri 20 Apr 2018: 2.00pm [QE] – Jenny on “Competitive interactions between scleractinian corals and macroalgae on heavily impacted reefs”

Department of Biological Sciences, NUS
Qualifying Examination

Competitive interactions between scleractinian corals and macroalgae on heavily impacted reefs

Speaker:              Jenny (Graduate Student, Dept. of Biological Sciences, NUS)
Date:                    20 April 2018, Friday
Time:                    2pm
Venue:                 DBS Conference Room II (S1, Level 3, mezzanine
Supervisor:          Assoc Prof  Peter A. Todd
Co-Supervisor:   A/P Suresh Valiyaveettil

Abstract: – Coral reef ecosystems are in global decline with macroalgae commonly replacing many scleractinian corals. On heavily impacted coral reefs where nutrients are elevated and herbivory is low, high levels of competitive interactions between corals and macroalgae are predicted. Macroalgae are able to suppress coral survival, growth, and reproduction, which can potentially lead to phase-shifts from coral- to algae-dominated reefs. The dynamics of coral–macroalgal interactions and the mechanisms involved, however, remain poorly understood.

My PhD thesis aims to (1) assess the spatial–temporal patterns of coral–macroalgal interactions on Singapore’s reefs, (2) examine the effects of macroalgal competition on coral physiology and microbiomes across various coral–macroalgal pairings, and (3) investigate the allelopathic effects of macroalgae as the potential mechanism mediating coral–macroalgal competition. My research will help improve our understanding on processes regulating coral–macroalgal competition and hence the long-term benthic community structure on impacted coral reef ecosystems.

All are welcome