Thu 30 Nov 2017: 10.00am [PhD Defense] – Cros Emilie Sidonie on “The emergence and loss of phenotypic and genomic diversity in Southeast Asian passerines”

PhD Defense Seminar cum Oral Examination
Department of Biological Sciences, NUS

“The emergence and loss of phenotypic and genomic diversity in Southeast Asian passerines”

Speaker:      Cros Emilie Sidonie (Graduate Student,Dept of Biological Sciences, NUS)         
Date:            30 Nov 2017, ThursdayEmilie.jpg
Time:            10am
Venue:         DBS Conference Room
Supervisor: Asst Prof Rheindt, Frank Erwin

Abstract –  “While half of the earth’s biodiversity resides in tropical regions, studies on the mechanisms and causes of recent biotic differentiation have mostly focused on the northern hemisphere. Understanding the biogeographical history of species in tropical regions is, however, important as it may help us predict their response to future changes and conserve tropical species diversity. Southeast Asia is a major biodiversity hotspots, and because of the periodical connectivity of its land masses due to sea level changes during Pleistocene glaciations, this region is particularly interesting for studying the evolutionary mechanisms governing differentiation. Southeast Asia’s biodiversity is particularly threatened by deforestation and habitat modifications associated with human growth, which makes this region also interesting for studying the mechanisms underlying the loss of diversity.

Using vocal and genomic data I studied the emergence and loss of phenotypic and genomic diversity in sylvioids of Southeast Asia. I found that Pleistocene glacial cycles have led to important vocal and genomic differentiation in populations found on different Sundaic landmasses. Additionally, genome-wide data suggest that those divergences happened after approximately 800 kya, a point marked by an increase in the intensity and length of Pleistocene glacial cycles. Finally, using comparative studies of species with a wide range of ecological characteristics, I found that characteristics that make some species genetically and phenotypically diverse also render them more prone to local extinction.”

All are welcome

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Jobs: Museum Officers (PhD required) @ LKCNHM (extended to 31 Jan 2017)

Details at the LKCNHM webpage.

The Lee Kong Chian Natural History Museum (LKCNHM) of the National University of Singapore invites applications to two Museum Officer positions. The successful candidates must be highly motivated and passionate about specimen-based research on Southeast Asian biodiversity as well as educating NUS students about Singapore and regional biodiversity.

As such, we are looking for candidates with a strong research CV, good communicators who can multi-task and are effective team players. Salary and benefits are commensurate with qualifications and experience.

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Fri 17 Nov 2017: 3.00pm [QE] – Zeng Yiwen on “Natural and human-mediated interactions between freshwater crabs and crayfish”

PhD Defense Seminar cum Oral Examination

“Natural and human-mediated interactions between freshwater crabs and crayfish”

Speaker:   Zeng Yiwen (Graduate Student Dept.of Biological Sciences, NUS)
Date:         17 Nov 2017, Friday
Time:         3pm
Venue:       Seminar Room 1 (S2 Level 4, #04-14)
Supervisor: Asst Prof Darren Yeo Chong Jinn

Abstract –  “Present day natural distributions of primary freshwater crabs and crayfish are largely allopatric, with crayfish being generally restricted to subtropical to temperate habitats globally, and crabs distributed around most tropical and sub-tropical regions. These non-overlapping distributions have been attributed to the two taxa being functionally similar, thereby having a high likelihood of interacting and competing with each other. Inter-taxa interactions can be an important biogeographical barrier to natural species dispersal. Such barriers, however, are breaking down as a result of the increased anthropogenic translocation and introduction of crayfish species beyond their native ranges into habitats containing native freshwater crabs. In spite of the implications associated with natural and human-mediated interactions between freshwater crabs and crayfish, few empirical studies have investigated such inter-taxa interactions to date, and the patterns and processes involved remain poorly understood.

I address this gap in knowledge and understanding via a series of studies at varying scales—ranging from global to regional to local. These studies involve the modeling of taxa richness and species distribution patterns (both spatially and temporally), in-situ field studies, and ex-situ behavioral experiments. Through such efforts, natural inter-taxa interaction is identified as a biotic factor that can influence biogeographical patterns of primary freshwater crabs and crayfish in some areas (e.g., the Mediterranean region), but not in others. The widespread introduction of non-indigenous crayfish species increases the chances for (human-mediated) inter-taxa interaction and competition to occur. The crayfish species Cherax quadricarinatus, for example, is predicted to co-occur and impact the greatest number of freshwater crab species in Southeast Asia regardless of future climate scenarios. This crayfish species already appears to have a negative impact on populations of the native freshwater crab, Parathelphusa maculata, within Singapore’s forest streams, with predation as well as competition for shelter being likely mechanisms for such impacts. These findings inform our understanding of the role that biotic factors can play in biogeographical processes, as well as the development and implementation of conservation strategies for native freshwater crabs.”

All are welcome

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Fri 17 Nov 2017: 10.00am [QE] – Nicholas Yap Wei Liang on “Sea anemone phylogeny, taxonomy and population genetics, with special reference to the frilly anemones, Phymanthidae”

Department of Biological Sciences, NUS
Qualifying Examination

“Sea anemone phylogeny, taxonomy and population genetics, with special reference to the frilly anemones, Phymanthidae”

Speaker:            Yap Wei Liang Nicholas (Graduate Student, Dept. of Biological Sciences, NUS)
Date:                  17 Nov 2017, Friday
Time:                  10am
Venue:                DBS Conference room  (S3 Level 5)
Supervisor:        Asst. Prof Huang Danwei
Co-supervisor:  Dr Tan Koh Siang

Abstract: – Sea anemones (Cnidaria: Actiniaria) are one of the most successful and cosmopolitan marine invertebrates on Earth. Found across a range of latitudes and depths, many are engaged in important ecological processes. Despite this, there are few studies on anemones in biodiversity hotspots such as the Coral Triangle and the Indo-Pacific region. Inventories of tropical sea anemones, as well as knowledge about their ecological roles and conservation status remain scarce due to the challenges of identifying and inferring phylogenetic relationships among them. Because anemones have great morphological diversity, traits used to identify them appear to contradict their phylogeny. To date, molecular phylogenetic relationships inferred among many lineages are inconsistent with taxonomy and are poorly supported, a problem exacerbated by the lack of sampling for tropical species.

My dissertation will re-evaluate conventional sea anemone taxonomic characters and their impact on systematics. I focus on a group of tropical, frilly anemones that are understudied and taxonomically unresolved—Phymanthidae.  I aim to: i) test the reliability of taxonomic characters associated with the anemone’s stingers [=cnidae], ii) revise the taxonomy of Phymanthidae, iii) reinterpret phylogenetic relationships with the inclusion of a larger sampling of tropical shallow-water species, iv) determine genetic connectivity of common tropical species around the Malay Peninsula and v) characterize the reproductive modes of Phymanthidae members. Also, I intend to deliver (vi) an updated checklist of anemones found in Singapore to facilitate further research here and in nearby regions.

All are welcome