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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Predator personality and prey behavioural predictability jointly determine foraging performance (Chang et al., 2017)

Chang, C. C., H. Y. Teo, Y. Norma-Rashid & D. Li, 2017. Predator personality and prey behavioural predictability jointly determine foraging performance. Scientific Reports, 7: 40734 [pdf].

Predator-prey interactions play important roles in ecological communities. Personality, consistent inter-individual differences in behaviour, of predators, prey or both are known to influence inter-specific interactions. An individual may also behave differently under the same situation and the level of such variability may differ between individuals. Such intra-individual variability (IIV) or predictability may be a trait on which selection can also act. A few studies have revealed the joint effect of personality types of both predators and prey on predator foraging performance. However, how personality type and IIV of both predators and prey jointly influence predator foraging performance remains untested empirically.

Here, we addressed this using a specialized spider-eating jumping spider, Portia labiata (Salticidae), as the predator, and a jumping spider, Cosmophasis umbratica, as the prey. We examined personality types and IIVs of both P. labiata and C. umbratica and used their inter- and intra-individual behavioural variation as predictors of foraging performance (i.e., number of attempts to capture prey).

Personality type and predictability had a joint effect on predator foraging performance. Aggressive predators performed better in capturing unpredictable (high IIV) prey than predictable (low IIV) prey, while docile predators demonstrated better performance when encountering predictable prey. This study highlights the importance of the joint effect of both predator and prey personality types and IIVs on predator-prey interactions.

Extinction debt: Singapore forest fragments are arks of ginger diversity but they are all small, threatened populations (Niissalo et al., 2017)

From Ted Webb, “PhD student Matti Niissalo suggests that many of the gingers of Singapore are under immediate threat of extinction or have an unpaid extinction debt; but that the prolonged period before extinction provides a window of opportunity for conservation action.”

Niissalo, M. A., J. Leong-Škorničková, G. S. Khew & E. L. Webb, 2017. Very small relict populations suggest high extinction debt of gingers in primary forest fragments of a tropical city. American Journal of Botany, 104(1): 182-189 [journal link]

Tropical plant communities in fragmented forests are likely to experience an extinction debt, i.e., the habitat cannot support as many species as are present due to reduced habitat size and connectivity. There are few estimates of the number of species that represent extinction debt, and the number of extinctions over time has rarely been recorded. We recorded population sizes to assess threats and extinctions in gingers (sensu Zingiberales) in fragmented rainforest in Singapore, ca. 200 yr after fragmentation began.

We surveyed extant diversity and population sizes of gingers and used the results to estimate species survival. We critically assessed historic specimens to estimate initial extinctions and extinctions realized in present habitats.

We recorded 23 species, including five species previously presumed nationally extinct and four species omitted from the national checklist. The revised extinction rate is much lower than previously reported (12 vs. 37%). Most gingers have very small populations or miniscule ranges, implying that extinction debt has not been paid off.

Ginger diversity remains high, but the number of species at immediate risk of extinction outnumber recorded extinctions. Although tropical forest fragments remain arks of plant diversity for a long time, extinction debt may be prevalent in all plant groups in Singapore. Slow relaxation of extinction debt should be explicitly identified as a conservation challenge and opportunity. For conserving plant diversity in tropical fragments, relaxation must be reversed through restoration of degraded landscapes and, where feasible, targeted ex situ conservation and planting.

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The classification of secondary forests of Singapore: native-dominated secondary forests, abandoned land forests and waste-woodlands (Yee et al 2016)

Yee, A. T. K., K. Y. Chong, L. Neo & H. T. W. Tan, 2016). Updating the classification system for the secondary forests of Singapore. Raffles Bulletin of Zoology Supplement No. 32: 11-21 [pdf].

In this paper, the authors examine dryland secondary forests of Singapore with a defied tree canopy layer (i. e. not scrubland). They classify these secondary forests based on their land-use histories into three forest types:

  1. Native-dominated secondary forests – forests regrown on land cleared before the 1950s, and dominated by native tree species.
  2. Abandoned-land forests – forests regrown over abandoned plantations or kampungs, with mature trees largely intact.
  3. Waste-woodlands – forests regrown over land cleared usually after the 1960s, and dominated by exotic tree species. Species composition derived from seed source of the surroundings at the time of clearance, and succession. Reclaimed land forest (technically primary succession) is structurally similar to waste-woodlands with a species composition likely derived from the fill material.”

The authors remind us that land-use history of a single patch of secondary forest can be heterogeneous, and would require a mixed classification to best describe it.

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See also, Yee, A. T. K., R. T. Corlett, S. C. Liew & H. T. W. Tan, 2011. The vegetation of Singapore—an updated map. Gardens’ Bulletin Singapore, 63(1&2), 205-212 [pdf].

“Vegetation covers 56% of Singapore’s total land area: 27% is actively managed (parks, gardens, lawns, etc.) and 29% is spontaneous vegetation. Primary lowland dipterocarp forest and freshwater swamp forest cover only 0.28% and is confined to the Bukit Timah and Central Catchment Nature Reserves. The majority of the non-managed vegetation is secondary forest of various kinds, dominated by native or alien trees.”

Painted Jezebels and relatives have deterred predators first with yellow, then red – Jocelyn Wee’s honours project with Antónia Monteiro published in PLoS

The Painted Jezebel is common sight around Singapore in both nature reserves and urbanised areas, including the NUS campus (see this post at Butterfly Circle). They are well recognised by the colours on their hindwings, the undersides of which bear bright yellow and red colours.

Sensing danger, most butterflies will fold and hold their wings over their body, exposing their undersides, i.e. ventral wing surfaces, during an attack. It is presumed that these colours advertise a butterfly’s unpleasant taste to predators, deterring attack. However, this has not actually been empirically demonstrated, even though the asgenus is a diverse one, ranging over South Asia and Australia.


Last year undergraduate Jocelyn Wee set out on her honours project with Antónia Monteiro to experimentally test is the colours of Delias hyparete function as aposematic signals.

To do this, Jocelyn constructed artificial paper models with a faithful colour representation of D. hyparete and a grey scale model. She also produced models with single colours intact, grey-scale models or models with no colours. All models were placed simultaneously in the field, with a live mealworm attached. The relative attack rates were measured on 100 models each at three separate field sites – Kent Ridge Road, Tampines Eco-Green and Jurong Eco Garden.

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Faithful models of D. hyparete suffered the least amount of attacks, followed by grey-scale models with unaltered red patches, and then by grey-scale models with unaltered yellow patches. They concluded that red and yellow colours function as warning signals.

Next, they mapped dorsal and ventral colouration onto the phylogeny of Delias. This revealed that yellow and red colours appear almost exclusively on the ventral wing surfaces. Basal lineages have mostly yellow, white, and black wings, whereas derived lineages contain red colour in addition to the other colours. Red appears to be, thus, a novel adaptive trait in this lineage of butterflies.

This work was published last week at PLoS as Wee, J. L. Q. & Monteiro, A., 2017. Yellow and the novel aposematic signal, red, protect Delias butterflies from predators. PloS one, 12(1), e0168243.

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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.