Research in my laboratory focuses on the ecology, evolution, biogeography, and conservation of butterflies and other organisms in Southeast Asia.
In terms of number of species, number of individuals, or sheer biomass, insects are the dominant multicellular organisms inhabiting the planet's terrestrial biomes. Of the 30+ orders of insects, the taxonomy, distribution, and habits of the Lepidoptera (butterflies and moths) are perhaps best characterized, making this group well suited to comparative analyses.
Current research focuses on several inter-related themes: 1) the phylogeography of butterflies and other organisms across the Indo-Australian Archipelago; 2) the community ecology of lepidopteran herbivores in the Asian tropics; 3) the role of Buddhism and other religions in biodiversity conservation in Southeast Asia; 4) the evolution of mimicry in Elymnias butterflies (Nymphalidae: Satyrinae).
Phylogeography of Volant Animals in Southeast Asia
Studies of island biogeography and geographical vicariance have been instrumental in understanding the spatial distribution of biodiversity. The Indo-Australian Archipelago (IAA) in Southeast Asia comprises thousands of islands and is divided by one of the most abrupt biogeographical transitions in the world: Wallace's Line. It is perhaps for these reasons that Alfred R. Wallace's nineteenth century observations in the IAA stimulated the development of biogeography (or zoogeography) as a field of study. Until recently, pragmatic considerations hindered the application of methodological advances made in other regions to the study of biogeography in the IAA, despite its suitability as a natural laboratory. However, the past ten years have seen a flurry of renewed investigation, including a number of studies on the geology of the region and molecular phylogenetic investigations of the organisms that inhabit it.
I have investigated the phylogeography of several widespread butterfly and bird species found on many of the region's major land masses, and found that some populations of these "widespread" species are distinct enough to merit recognition as distinct species. In addition, I uncovered novel spatial patterns of genetic variation and Wolbachia infection across the IAA.
D.J. Lohman*, M. de Bruyn*, T. Page, K. von Rintelen, R. Hall, P. K. L. Ng, H.-T. Shih, G. C. Carvalho, & T. von Rintelen. 2011. Beyond Wallace's Line: genetics and geology inform biogeographical insights in the Indo-Australian Archipelago. Annual Review of Ecology, Evolution, and Systematics. In press. *joint first authors [TOC]
Lohman, D.J., K.K. Ingram, D.M. Prawiradilaga, K. Winker, F.H. Sheldon, R.G. Moyle, P.K.L. Ng, P.S. Ong, L.K. Wang, T.M. Braile, D. Astuti & R. Meier. 2010. Cryptic genetic diversity in "widespread" Southeast Asian bird species suggests that Philippine avian endemism is gravely underestimated. Biological Conservation 143: 1885-1890. [Abstract]
Sheldon, F.H., D.J. Lohman, H.C. Lim, F. Zou, S.M. Goodman, D.M. Prawiradilaga, K. Winker, T.M. Braile & R.G. Moyle. 2009. Phylogeography of the magpie-robin species comples (Aves: Turdidae: Copsychus) reveals a Philippine species and novel dispersal patterns in the Indian Ocean and S.E. Asia. Journal of Biogeography 36: 1070-1083. [Abstract]
Lohman, D.J., D. Peggie, N.E. Pierce & R. Meier. 2008. Phylogeography and genetic diversity of a widespread Old World butterfly, Lampides boeticus (Lepidoptera: Lycaenidae). BMC Evolutionary Biology 8: 301. [PDF] [Additional File]
Community Ecology of Tropical Lepidoptera
Systematic studies of the spatial distribution and turnover of tropical trees in large forest plots have been instrumental in understanding the ecology of tropical forests. Many of these large plots are part of the network established and maintained by the Center for Tropical Forest Science (CTFS). Plots in the CTFS network are typically 50 ha in size, and every tree is mapped, measured (DBH), and identified to species. Plots are re-censused every five years to obtain a dynamic picture of tropical forest diversity and composition.
CTFS and its in-country collaborators maintain a research staff and facilities at each cite, but, until recently, trees were the only group that were studied systematically. To build upon this foundation while taking advantage of the existing tree data, I began examining in 2005 the ecology of next trophic level--insect (lepidopteran) herbivores--at the Khao Chong plot in southern Thailand. With the help of CTFS, 2-4 field assistants, and several in-country collaborators, we have monitored seasonal changes in butterfly and moth diversity in the understory and in the canopy through weekly sampling of adults over 5 years. On a weekly basis, we also searched every leaf on every plant in two 10 x 40m subplots and on 80 focal trees of four species to examine host plant specialization and the spatial ecology of insect herbivory.
While currently analyzing data from the first 3+ years of this project, my collaborators and I are looking ahead to expanding the number of sampling sites to examine patterns along a latitudinal gradient. In addition, we are investigating ways of expediting specimen identification by using DNA sequences and exploring the utility of community phylogenies to understand the phylogenetic structure of herbivores in relation to that of their plants between wet/dry seasons and among sites.
Basset, Y., R. Eastwood, L. Sam, V. Novotny, T. Treuer, D.J. Lohman, V. Novotny, S.E. Miller, G.D. Weiblen, N.E. Pierce, S. Bunyavejchewin, W. Sakchoowong, P. Kongnoo & M.A. Osorio-Arenas. In press. Cross-continental comparisons of butterfly assemblages in rainforests: implications for biological monitoring. Insect Conservation and Diversity.
Basset, Y., R. Eastwood, L. Sam, V. Novotny, T. Treuer, D.J. Lohman, V. Novotny, S.E. Miller, G.D. Weiblen, N.E. Pierce, S. Bunyavejchewin, W. Sakchoowong, P. Kongnoo & M.A. Osorio-Arenas. 2011. Rainforest butterfly assemblages compared across three biogeographical regions using standardized protocols. Journal of Research on the Lepidoptera 44: 17-28. [PDF]
Buddhism and biodiversity conservation in Southeast Asia
Curbing the loss of biodiversity and natural habitats is one of the planet's most pressing issues, and this problem is most acute in South and Southeast Asia. ropical rain forests are the most biologically diverse terrestrial ecosystems on Earth and are found almost exclusively in developing countries. Economic realities often force the destructive extraction of forest resources for short-term gain (e.g., timber and bush meat), thus destroying their long-term value.
Biologists have been sounding the alarm bells about the dangers of habitat loss and species extinction for many years, and it is now clear that the solutions to curbing the planet's current mass extinction event will be inherently non-biological. These remedies will require cross-disciplinary efforts, and E.O. Wilson has argued that public education campaigns work too slowly to curb the planet's biodiversity loss before it is too late. He argues that religion provides the most effective conduit to communicate conservation imperatives with a large audience in an expedient manner.
We are currently surveying the diveristy of several indicator taxa in Buddhist temples and surrounding areas in Thailand and in Sri Lanka to assess the role that these temples have played in biodiversity conservation. In tandem with these surveys, we are surveying monks and villagers who live in and around these temples to gauge their attitudes toward conservation and their role as environmental stewards.
Sodhi, N.S., T.M. Lee, C.H. Sekercioglu, E.L. Webb, D.M. Prawiradilaga, D.J. Lohman, N.E. Pierce, A.C. Diesmos, M. Rao & P.R. Ehrlich. 2010. Local people value environmental services provided by forested parks. Biodiversity and Conservation, 19: 1175-1188. [Abstract]
Evolution of Batesian mimicry in Elymnias butterflies (Nymphalidae: Satyrinae) (NSF DEB 1120380)
The butterfly genus Elymnias is a little-studied but species-rich group of Batesian mimics distributed primarily in Southeast Asia. Species vary in color, pattern, and size because different Elymnias species frequently mimic dramatically different models. Despite its potential as a system for studying mimicry, the evolution of wing patterns, and Southeast Asian biogeography, there has been virtually no biological research on this genus.
Using multiple, independent genetic loci, we and the laboratory of Shen-Horn Yen will generate a phylogenetic tree to address several key questions, including: 1) Have similar mimetic wing patterns evolved convergently? 2) Does the inferred timescale of diversification conform to hypotheses regarding the biogeographical history of Southeast Asia? 3) Have isolated islands been colonized more than once, or have their respective suites of endemic species diversified in situ? 4) Is divergence within a single landmass associated with shifts in mimetic color pattern?
Because of its species richness and extreme interspecific morphological diversity, Elymnias promises to be an unparalleled system for the study of wing pattern evolution and the evolution of morphological novelty.
Parasite control of host behavior in the slave-making ant Protomognathus americanus
Protomognathus americanus is a cavity dwelling, obligate brood parasite of several Temnothorax spp. ants. During slave raids, P. americanus captures brood of the host species and rears them as its own. The slaves carry out all foraging, brood care, and nest selection. Previous studies used free-living (unparasitized) Temnothorax ants as models for the study of collective decision making in nest cavity selection. Temnothorax ants typically prefer nests with larger volumes and ceiling heights but smaller entrances. Protomognathus americanus is larger than its host species and would presumably require larger entrances and greater nest volume than Temnothorax. If the slaves are an extension of the slave makers' phenotype, then enslaved Temnothorax may change their typical nest cavity selection criteria to accommodate the larger Protomognathus ants. We are current conducting choice tests in the lab to determine whether this parasite is capable of controlling the behavior of its host.
Diversity and dispersal potential of bat-borne zoonotic viruses in the Indo-Australian Archipelago (NIH 1R21AI105050)
In recent years, Asia has been the source of several emerging infectious diseases with high levels of mortality, including the SARS virus, H1N1 influenza virus, and Nipah virus. The severity of outbreaks can be mitigated when animal reservoirs are readily identified and their movements restricted, but when pathogens are vectored by flying organisms, containment can be difficult. The recent recognition of bats as putative sources of pathogens and the discovery of novel viruses has spurred research on their role as reservoir hosts. This is the case with large fruit bats known as flying foxes (Chiroptera: Pteropodidae: Pteropus), where there is evidence of infections from at least six virus families, including the highly pathogenic Paramyxoviridae. Colonial roosting, high vagility, and long lifespans provide the opportunity for viral persistence and intra- and inter-colony transmission. A single Pteropus bat can fly over 50 km in a single night, making these animals important long-range vectors for pathogens across. The large geographic range of Pteropus species further underlines the geographic extent and costs that bat-borne zoonoses might have on global health.
We are currently sampling Pteropus and their viruses throughout Indonesia and the Philippines to determine the presence and prevalence of zoonotic pathogens in relation to evolutionary history and ecological traits. Our collaborators in the Emerging Infectious Disease Program at Duke-NUS Medical School in Singapore, Vijaykrishna Dhanasekaran and Gavin Smith, will use RNA-based assays to detect the presence of any viruses, and subsequently clone and sequence them for comparison with other mammalian viruses. Nascent phylogeographic and network analyses will allow us to model the population structure of the host species and their dispersal routes, allowing containment efforts to focus on crucial dispersal corridors. We will then infer where viral hotspots may occur by using ecological niche modeling.