Singaporeans may be willing to pay $643.5 million/year for haze mitigation – 0.97% of annual income: Lin, Wijedasa & Chisholm (2017)

Lin Y., L.S. Wijedasa & R.A. Chisholm, 2017. Singapore’s willingness to pay for mitigation of transboundary forest-fire haze from Indonesia. Environmental Research Letters [free online version].

“Southeast Asian haze pollution caused by forest and peatland fires in Indonesia has caused adverse health effects, impacted regional economies and let to tensions between ASEAN nations. One of the solutions proposed is payments for ecosystem services. This could take the form of richer nations aiding better land management and restoration by making regular payments.

In this study, we assessed the willingness of Singaporeans to pay for haze mitigation in Indonesia. We surveyed a diverse set of individuals from different income groups, genders and locations throughout the country to quantify the willingness to pay (WTP) for haze mitigation.

Our estimate of mean individual WTP was 0.97% of annual income (n=390). This amounted to a total WTP estimate of US$643.5 million per year (95% CI [US$527.7 million, US$765.0 million]). This estimate is comparable in magnitude to previously estimated impacts of Indonesia’s fires and also to the estimated costs of peatland protection and restoration. We recommend that our results be incorporated into future cost–benefit analyses of the fires and mitigation strategies.”

Euphlyctis karaavali, a new species of frog from Karnataka, which calls like the white- throated kingfisher

Grad student K S Seshadri is working on threatened amphibians in the Western Ghats for his PhD dissertation, focusing on the ecology and behaviour of bamboo nesting frogs. His research is supported by the Mohamed bin Zayed Species Conservation Fund and Chicago Zoological Fund. He updates us about news of a discovery of another new species of frog from the area:

“I’m happy to share with you the news of a new species of frog that we discovered from the West Coast of India. We described it as Euphlyctis karaavali, named after the local name of the west coast in Kannada language.

We chanced upon this frog entirely by serendipity. The frog call is very similar to that of the white throated kingfisher, commonly found in India. Mr. C. R. Naik, a forester with the state forest department brought this frog to our attention during his surveys along the coastal plains. We got him on board and wrote this paper along with him. This discovery is significant considering a forest department official with no formal training in research made the discovery and is an author of this contribution to science.

The frog is already threatened and we suggest that it be listed as Endangered under the IUCN redlist. The paper was published in Asian Herpetological Research, and is openly accessible.

Kingfisher-like call of Euphlyctis karaavali

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Thu 19 Jan 2017: 10.00am @ DBS CR1– Nesibe Özsu on “The genetic basis of eyespot color pattern development in Bicyclus anynana butterflies”

Image004PhD Defense Seminar cum Oral Examination

The genetic basis of eyespot color pattern development in Bicyclus anynana butterflies

Speaker: Nesibe Özsu (Graduate Student Dept.of Biological Sciences, NUS)
Date: 19 January 2017, Thursday
Time: 10 am
Venue DBS Conference Room (S3 Level 5)
Supervisor: Assoc Prof Antonia Monteiro

All are welcome

Abstract – The origin of novel traits remains an outstanding question in evolutionary biology. In particular, it is largely unknown how these novel traits originate via modifications in development. Butterfly eyespots are complex novel traits that originated once, from simpler coloured spots, within the family Nymphalidae. Although several genes associated with eyespot development have been identified, the underlying gene regulatory network and function of eyespot genes still remains largely unknown.

Using a transcriptome analysis, I first identified 186 genes that were differentially expressed in wing tissues that develop eyespots in Bicyclus anynana compared to wing tissues that don’t. Many of these genes were involved in wound healing, suggesting that butterfly eyespots may have originated with the co-option of the wound healing gene regulatory network. Second, I investigated the genetic basis of eyespot number variation using an eyespot number mutant, Spotty, with two additional eyespots. Only a handful of the 461 genes that were differentially expressed between Spotty and wild-type butterflies overlapped with genes from the eyespot gene regulatory network, indicating possible targets for Spotty. Finally, I tested the function of wingless, a gene previously implicated in eyespot development, by down-regulating it in transgenic B. anynana butterflies via RNAi. Transgenic butterflies showed significant reductions in the size of eyespots and wings, compared to wild-type controls, indicating that wingless is a positive regulator of eyespot and wing development in B. anynana butterflies.

Fri 13 Jan 2017: 10.00am @ DBS CR1 – Mindy Tuan on “Comparative and experimental approaches to understanding sexual selection in Sepsidae (Diptera)”

Image004PhD Defense Seminar cum Oral Examination

“Comparative and experimental approaches to understanding sexual selection in Sepsidae (Diptera)”

Speaker: Tuan Jia Min Mindy
(Graduate Student, Dept. of Biological Sciences ,NUS)
Date: 13 January 2017, Friday
Time: 10 am
Venue: DBS Conference Room (S3 Level 5)
Supervisor: Professor Meier, Rudolf

All are welcome

Abstract – Natural history and discovery science has taken a back-seat as hypothesis-testing using model species has become a standard approach in biology. This is one reason why the vast majority of described species are severely data-deficient and very little is known is known about their behaviour, interactions with other species, and ecosystem functions. In my thesis, I explore the behavioural diversity within black scavenger flies (Diptera: Sepsidae) which have ca. 350 described species. Sepsidae include a few “model species” (e.g., Sepsis cynipsea, Sepsis punctum, and a few species of Themira, Archisepsis and Microsepsis), but little is known about the remaining taxa. In my thesis, I use a comparative approach to explore the behavioural diversity space of Sepsidae by studying the mating behaviour of 49 species and use comparative and experimental approaches to document and understand the behaviour.

I find that sepsids are one of the few insects that perform “sensory kissing”, which is significantly different from the nuptial kissing observed in other dipterans or the kissing performed by drosophilids to assess females’ receptivity before mating. Sepsids also evolved a variety of ways to terminate copulations. For example, some species use a novel “twisting” motion that allows the male to “pivot” clock- or anti-clockwise in order to separate from the female. Data analysis suggests that this new behaviour is adaptive because it allows for faster and more predictable separation times. Similarly variable is copulation time. The copulation time of sepsids varies 5 minutes to 5 hours and I show through ancestral state reconstruction and sensitivity analyses that copulation time undergoes considerable amounts of evolution. Furthermore, I used experimental reciprocal crosses between separated conspecific populations to determine which sex controls copulation duration. Experimental perfuming of females using osmeterium secretions from males were also performed to test whether the secretion possessed an anti-aphrodisiac function. Finally, I detailed the repertoire, action patterns and phases for 24 species of sepsids.

This work revealed interesting and rare behaviours, as well as widespread polymorphism within species, which would have remained hidden if only model species had been studied. This illustrates the importance of comparative research on the natural history of many species. It both broadens and deepens our knowledge of animal diversity.

Fri 13 Jan 2017: 2.00pm @ DBS CFR2 – Pang Sook Cheng on Distribution and bionomics of Anopheles sinensis, and its role of the malaria transmission in Singapore

Image003PhD Defense Seminar cum Oral Examination

Distribution and bionomics of Anopheles sinensis, and its role of the malaria transmission in Singapore

Speaker: Pang Sook Cheng
(Graduate Student Dept. of Biological Sciences, NUS)
Date: 13 January 2017, Friday
Time: 2pm
Venue: DBS Conference Room II (S1 Level 3, mezzanine)
Supervisor: Assoc Prof Li Daiqin

All are welcome

Abstract – Research on Anopheles mosquitoes has always been of low priority due to the malaria free status of Singapore since 1982. However, Anopheles sinensis were persistently found in localized malaria outbreaks in 2009 and kick started the investigation on the distribution, bionomics and the role of malaria transmission of this species. In this study, we confirmed the presence of A.sinensis Form A and the possible absence of Form B in Singapore.

Anopheles sinensis Form A was experimentally incriminated as a Plasmodium vivax vector and were found to be anthropophilic. Being the most widespread anopheline, they were present in a third of the total investigated sites and were actively seeking host throughout the night, especially before 1.00am. In the wild, their abundance positively correlative with the average and minimum temperature, but not rainfall.

Basic biological characteristics of A. sinensis were also pursue to further understand the fundamental knowledge to epidemiology of malaria. This study has revealed that A. sinensis could pose a malaria threat in urban Singapore, if the risks are not managed.

From Ng Ting Hui’s PhD thesis, paper in PLoS One – “Molluscs for Sale: Assessment of Freshwater Gastropods and Bivalves in the Ornamental Pet Trade”

On Monday 21 Nov 2016, Ting Hui will present her work during her oral exam, and all are invited! The work was featured in the The Straits Times today.

NG, Ting Hui, Siong Kiat Tan, Wing Hing Wong, Rudolf Meier, Sow-Yan Chan, Heok Hui Tan, Darren C. J. Yeo, 2016. Molluscs for Sale: Assessment of Freshwater Gastropods and Bivalves in the Ornamental Pet Trade. PloS one, 11(8), e0161130 (free download).

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The ornamental pet trade is often considered a key culprit for conservation problems such as the introduction of invasive species (including infectious diseases) and overharvesting of rare species. Here, we present the first assessment of the biodiversity of freshwater molluscs in the ornamental pet trade in Singapore, one of the most important global hubs of the ornamental aquarium trade, and discuss associated conservation concerns. We recorded freshwater molluscs from ornamental pet shops and major exporters including non-ornamental species (e.g., hitchhikers, molluscs sold as fish feed).

We recorded an unexpectedly high diversity—59 species—of freshwater bivalves and gastropods, with the majority (38 species or 64%) being from the Oriental region. In addition to morphological examination, we sequenced the DNA barcode region of mitochondrial CO1 and 16S genes to provide molecular data for the confirmation of the identification and for future re-identification. DNA barcodes were obtained for 50 species, and all but four were separated by > 3% uncorrected pairwise distances.

The trade has been considered a main introduction pathway for non-native species to Singapore, and we found that out of 15 species in the trade as well as in the wild in Singapore, 12 are either introduced or of unknown origin, representing almost half of the known non-native freshwater molluscs in Singapore. Particularly prevalent are non-ornamental species: six hitchhikers on aquarium plants and six species sold as fish feed. We found that a quarter of the trade species have a history of introduction, which includes 11 known or potentially invasive species. We conclude that potential overharvesting is difficult to assess because only half of the trade species have been treated by IUCN. Of these, 21 species are of Least Concern and three are Data Deficient.

Our checklist, with accompanying DNA barcodes, images, and museum vouchers, provides an important reference library for future monitoring, and constitutes a step toward creating a more sustainable ornamental pet trade.

Mon 21 Nov 2016: 2.00pm @ SR1 – Ng Ting Hui on “Introduction and Impacts of Freshwater Gastropods In Singapore”

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

“Introduction and Impacts of Freshwater Gastropods In Singapore”

Ng Ting Hui (Graduate Student, NUS DBS)
Mon 21 Nov 2016: 2.00pm @ Seminar Room 1 (S2 Level 4)
Supervisor: Asst Prof Darren Yeo Chong Jinn; Co-supervisor Dr. Tan Heok Hui

Abstract – Freshwater snails (Gastropoda) in Southeast Asia are among the most diverse aquatic groups. Like freshwater molluscs globally, they are threatened by, among other things, aquatic invasive species. Fourteen gastropod species have been introduced in Southeast Asia, including globally-invasive and cryptogenic species (of unknown origin), with Singapore having the highest number (23 species). Freshwater gastropods in Singapore are almost exclusively found in urban habitats, including human commensal native species suspected to have been introduced. Clarifying the status of these and other poorly-known freshwater gastropods can help to prioritise conservation and management efforts of native and invasive species, respectively. My thesis therefore aims to examine the origins and potential impacts of introduced freshwater gastropods in Singapore.

I began with a morphological and molecular study of freshwater mollusc diversity in the ornamental pet trade, the key introduction pathway for aquatic organisms in Singapore. Fifty-nine species (most from the Oriental region) were recorded in the trade, accounting for almost half of known introduced freshwater molluscs in Singapore, including the globally-invasive New World apple snails, Pomacea spp. (Ampullariidae). This led me to investigate the Ampullariidae in Singapore, and I confirmed the establishment of two superficially similar South American species, Pomacea canaliculata and Pomacea maculata. Surprisingly, the purportedly native Pila scutata, was found to be a human commensal, and probably introduced to Singapore instead (further reinforced by demonstrated resistance to anthropogenic habitat disturbance in subsequent stable isotope studies).

To resolve this, I then surveyed Pila scutata in Peninsular Malaysia and Singapore to investigate its distribution and genetic diversity. I found that Pila had been displaced by Pomacea at most historical sites. Only one Pila scutata population in Malaysia and six in Singapore were found, with all individuals sharing a single haplotype—further strong evidence that these populations were introduced by humans.

Pila nevertheless remains a native Southeast Asian genus, so I investigated the potential impacts of South American Pomacea on Pila in terms of feeding ecology. Stable isotope analysis showed no resource overlap between these taxa in habitats where they co-occur, while ex-situ experiments comparing feeding rates indicated that Pomacea feeds more quickly than Pila. My results indicate that Pila may be able to persist at sites where it is syntopic with Pomacea, but further studies are required to understand the interactions between the taxa.

Though my study mostly focussed on apple snails, non-ampullariids, constituting > 80% of Singapore’s introduced gastropods, are also important components of the ecosystem that should not be overlooked. In the course of this study, I clarified the confused taxonomy of two long-established species, Sinotaia guangdungensis (Viviparidae) and Physa acuta (Physidae), and reported two new records of introduced species, Pyrgophorus platyrachis (Cochliopidae) and Anentome helena (Nassariidae). Based on my study, the number of freshwater mollusc species in Singapore is now updated to 4 native, 15 introduced, and 10 cryptogenic.

Overall, this thesis provides, for the first time, important baseline information and further research directions on various aspects of introduced freshwater molluscs in Southeast Asia, which are more widespread than previously thought.