GREGORY H. ADLER

Founder and CEO of The Tropical Rat Lab

In a Xinu village, northern Colombia, study site for a leishmaniasis project.  Photo by Dr. B. L. Travi.

Education and training:

• B. S. in Biology, 1979, Washington and Lee University
• Ph. D. in Biology, 1986, Boston University
• Postdoctoral Research Fellow and Associate, Harvard School of Public Health, 1987-1992
• Postdoctoral Specialist, University of California - Davis, 1988
• Visiting Scientist, Tunghai University, Taichung, Taiwan, 1990
• Postdoctoral Fellow, Smithsonian Tropical Research Institute, Panama, 1990-1993
• Visiting Scientist, International Center for Medical Training and Research, Cali, Colombia, 1993

Courses I teach:

• Ornithology
• Ecology and Evolution
• Population and Community Ecology

Research interests:

• My major research questions are 1) what factors limit densities of animal populations and are populations regulated by density-dependent mechanisms, 2) what are the roles of resource abundance and intraspecific interactions in shaping population trajectories, 3) how can ecological principles be applied to control disease transmission, 4) what are the roles of tropical forest animals in forest ecosystems, and 5) what are the population- and community-level consequences of tropical forest fragmentation?   To address these questions, I have used primarily rodents because they are often abundant, easily sampled, easily manipulated, and hence are excellent model organisms for hypothesis-testing.  Much of my work has been devoted to island populations and communities.  Because islands are isolated, they can function essentially as closed systems and hence are ideal for conducting manipulative experiments without problems of immigration and emigration.  Because islands are discrete, entire populations may be marked and studied.  Islands also occur widely around the globe and in a remarkable variety of sizes and types.  Thus, after certain patterns have been documented, it is necessary to adopt an experimental approach to identify the underlying processes.

• Early in my postdoctoral research, I became keenly interested in the tropics because of 1) the nearly complete lack of any long-term experimental work at the population or community levels, 2) the extraordinary diversity and complexity of tropical systems, and 3) the broad range of diseases with mammalian reservoirs that affect human populations.  The rapid disappearance of tropical systems provided further impetus for undertaking research in the tropics because of the especial urgency in understanding such systems.  Furthermore, previous studies were primarily descriptive and of short duration.  I needed first an appropriate system with which to work.  I conducted three months of field work in Panama in 1989 to census rodents on islands in Gatun Lake.  I found one species of rodent (Proechimys semispinosus, the spiny rat) to be widely distributed and abundant on small islands.  Other species of rodents, despite being present on the adjacent mainland (about 16 mouse- and rat-like species), were completely absent from the islands.  Based upon this census, I began a long-term experimental study (funded by the National Geographic Society, the Smithsonian Institution, and the National Science Foundation).  My immediate goal was to accumulate requisite natural history information on this species to better address the five primary questions.  My ultimate goal has been to extend the analysis to include other species of rodents by building model communities on the islands.

• Accordingly, I am now using these islands as experimental systems to examine 1) the influence of tropical tree diversity and forest structure on the demography of the spiny rat, 2) the effects of forest fragmentation on isolated populations of spiny rats, 3) the influence of resource density on the demography of spiny rats, 4) the role of spiny rats as seed predators and dispersers and as arbuscular mycorrhizae fungal spore dispersers, 5) density-dependent mechanisms of population regulation in spiny rats, and 5) population-level interactions between spiny rats and other frugivorous rodents.  As part of this integrated study, I have marked and censused monthly all the spiny rats on 12 2-ha islands for the past nine years (about 20,000 captures of four thousand individuals), and I have marked, measured, mapped, and identified every tree > 10 centimeters dbh on each island (over 20,000 trees of about 230 species).  I have also measured a series of variables related to forest structure on these islands.  From the first 12 months of unmanipulated census data, I examined the relationships between spiny rat demography, tree species composition, and forest structure.  I found that these isolated spiny rat populations do not have synchronous fluctuations, quite unlike temperate rodents.  In the second year, I manipulated resource density to test the hypothesis that spiny rats are not food-limited during the rainy season (the season of resource abundance).  In subsequent years, I manipulated age and sex ratios to determine the roles of adult males and females in regulating population densities via intraspecific interactions and density-dependent changes in reproductive effort.  I am now simultaneously manipulating age and sex ratios and resource abundance to examine the interplay between resource limitation and intrinsic regulating mechanisms.  Throughout the study, I have been conducting monthly phenological censuses of all trees on the 12 study islands to determine patterns of fruit availability, the impact of such availability on spiny rat populations, and reproductive phenologies of a large number of tropical tree species.

•  My graduate students and I have been examining interactions between P. semispinosus and the closely-related Hoplomys gymnurus (the armored rat).  The major thrust of this project is to determine why P. semispinosus is so abundant and widely distributed and H. gymnurus is so much more restricted in abundance and distribution despite their morphological, phylogenetic, and ecological similarities.  We also are examining the effects of tropical forest fragmentation on rodent community diversity and structure in both Panamá and Venezuela.

• I have been working for the past several years on the dynamics of visceral leishmaniasis (Leishmania chagasi) infection in the common opossum (Didelphis marsupialis) and a spiny rat (Proechimys canicollis) in northeastern Colombia (funded by the World Health Organization and the government of Colombia).  The area is originally tropical dry forest but has been heavily disturbed.  Densities of opossums in this area are extremely high and are apparently the result of this disturbance.  High densities of opossums may in turn promote the maintenance of L. chagasi as an endemic focus of infection.  We have expanded this project to include nearby undisturbed tropical dry forest to examine differences in density and diversity of potential reservoirs and the incidence and dynamics of L. chagasi infection in such reservoirs.  In an earlier study in the western Andes of Colombia, we used molecular techniques to discover infection by Leishmania braziliensis (the agent of cutaneous leishmaniasis) in several species of mammals that previously were not known to be infected by this parasite.  We have been using this technique to screen for L. chagasi infection in mammals in our current study and have found interesting seasonal patterns of infection that can be explained partly by seasonal activity of vectors.

• My students and I have been conducting biodiversity inventories in so-called biodiversity "hotspots".  One such survey has involved a collaboration with Russian and Vietnamese scientists to survey rodents and other mammals in a remote forested region in the Central Highlands of southern Viet Nam.  Other inventoried areas include the remote Darien region of eastern Panama, the lowlands of central Panama, and the Chiriqui Highlands of western Panama.

• Tropical forest fragmentation and disturbance pose serious conservation threats and may actually promote transmission of diseases to humans by promoting the abundance of a few species that are able to efficiently exploit disturbed areas. My work therefore relates directly to the ecological consequences of fragmentation and disturbance, including demographic effects of insularity, declining biotic diversity, and disease transmission.

Publications:

• McKee, R. C., and G. H. ADLER.  2002.  Tail autotomy in the Central American spiny rat, Proechimys semispinosus.  Studies on Neotropical Fauna and Environment, in press.

 
• Suntsov, V. V., T. V. H. Ly, and G. H. ADLER.  2002.  Distribution of rodents along a gradient of disturbance on the Tay Nguyen Plateau of southern Viet Nam.  Mammalia, in press.

 
• Travi, B. L., L. T. arteaga, A. P. Leon, and G. H. ADLER.  2002.  Susceptibility of spiny rats (Proechimys semispinosus) to Leishmania (Viannia) panamensis and Leishmania (Leishmania) chagasi. Memorias Oswaldo Cruz, in press.

 
• Travi, B. L., C. Ferro, G. H. ADLER, and J. Montoya-Lerma.  2002.  Canine visceral leishmaniasis: dog infectivity to sand flies from non-endemic areas.  Research in Veterinary Science, in press.

 
• Travi, B. L., G. H. ADLER, M. Lozano, H. Cadena, and J. Montoya-Lerma.  2002.  Impact of habitat degradation on Phlebotominae (Diptera: Psychodidae) of tropical dry forests in northern Colombia, an endemic area of visceral and cutaneous leishmaniasis.  Journal of Medical Entomology, in press.

 
• Mangan, S. A., and G. H. ADLER.  2002.  Seasonal dispersal of arbuscular mycorrhizal fungi by spiny rats in a Neotropical forest. Oecologia, in press.

 
• Terborgh, J. L. Lopez, P. Numez V., M. Rao, G. Shahabuddin, G. Orihuela, M. Riveros, R. Ascanio, G. H. ADLER, T. D. Lambert, and L. Balbas.  2001.  Ecological meltdown in predator-free forest fragments. Science, 294:1923-1926

 
• ADLER, G. H., N. Suntsova, V. V. Suntsov, and S. A. Mangan.  2001.  Fleas (Siphonaptera) collected from small mammals in southern Viet Nam in 1997-1998.  Journal of Medical Entomology, 38: 210-213.

 
• ADLER, G. H.  2001.  La regulacion de las poblaciones de mamiferos. Pages 329-344 in M. R. Guariguata and G. H. Kattan (editors).  Ecologia y conservacion de bosques neotropicales.   Editorial Libro Universitario Regional, San Jose, Costa Rica.

 
• ADLER, G. H.  2001.  Rainforest ecosystems, animal diversity.  Pages 1-11 in S. A. Levin (editor).  Encyclopedia of biodiversity, Volume 5.  Academic Press, San Diego, CA.

 
• ADLER, G. H., and K. Kielpinski.  2000.  Reproductive phenology of a tropical canopy tree, Spondias mombin.  Biotropica, 32: 686-692.

 
• Boyett, W. D., M. J. Endries, and G. H. ADLER.  2000.  Colonization-extinction dynamics of opossums on small islands in Panama.  Canadian Journal of Zoology, 78: 1972-1979.

• ADLER, G. H., M. T. Becerra, F. Prado, and B. L. Travi.  2000.  Ecology of spiny rats, Proechimys canicollis, in northern Colombia. Mammalia, 64: 145-153.

 
• Mangan, S. A., and G. H. ADLER.  2000.  Consumption of arbuscular mycorrhizal fungi by terrestrial and arboreal small mammals in a Panamanian cloud forest.  Journal of Mammalogy, 81: 563-570.

• Lambert, T. D., and G. H. ADLER.  2000.  Microhabitat use by a tropical forest rodent, Proechimys semispinosus, in central Panama. Journal of Mammalogy, 81: 70-76.

• ADLER, G. H.  2000.  Tropical tree diversity, forest structure and the demography of a frugivorous rodent.  Journal of Zoology, 250: 57-74.

 
• Mangan, S. A., and G. H. ADLER.  1999.  Consumption of arbuscular mycorrhizal fungi by spiny rats (Proechimys semispinosus) in eight isolated populations.  Journal of Tropical Ecology, 15: 779-790.

• ADLER, G. H., S. A. Mangan, and V. Suntsov.  1999.  Richness, abundance, and habitat relations of rodents in the Lang Bian Mountains of southern Viet Nam.  Journal of Mammalogy, 80: 891-898.

• Seamon, J. O., and G. H. ADLER.  1999.  Short-term patterns of space use by a Neotropical forest rodent, Proechimys semispinosus. Journal of Mammalogy, 80: 899-904.

• ADLER, G. H., S. A. Mangan, and T. D. Lambert.  1998.  Reproductive phenology of Cryosophila warscewiczii in central Panamá. Principes, 42: 185-189.

• ADLER, G. H., D. C. Tomblin, and T. D. Lambert.  1998.  Ecology of two species of echimyid rodents (Hoplomys gymnurus and Proechimys semispinosus) in central Panama.  Journal of Tropical Ecology, 14: 705-711.

• Travi, B. L., Y. Osorio, M. T. Becerra, and G. H. ADLER.  1998.  Dynamics of Leishmania chagasi infection in small mammals of the undisturbed and degraded tropical dry forests of northern Colombia. Transactions of the Royal Society of Tropical Medicine and Hygiene, in press.

• Tomblin, D. C., and G. H. ADLER.  1998.  Habitat differences between two morphologically similar tropical forest rodents.  Journal of Mammalogy, 79: 953-961.

• Alexander, B, C. Lozano, D. G. Barker, S. H. E. McCann, and G. H. ADLER.  1998.  Detection of Leishmania (Viannia) braziliensis complex in wild mammals from Colombian coffee plantations by PCR and DNA hybridization.  Acta Tropica, 69: 41-50.

• ADLER, G. H., and D. W. Kestell.  1998.  Seed predation and scatterhoarding by spiny rats (Proechimys semispinosus). Biotropica, 30: 677-681.

• ADLER, G. H.  1998.  Impacts of resource abundance on populations of a tropical forest rodent.  Ecology, 79: 242-254.

• ADLER, G. H., J. J. Arboleda, and B. L. Travi.  1997.  Diversity and abundance of small mammals in degraded tropical dry forest of northern Colombia.  Mammalia, 61: 361-370.

• Seamon, J. O., and G. H. ADLER.  1997.  Factors affecting immigration of adults: experimental and theoretical observations with rodents. Acta Oecologica, 18: 637-655.

• ADLER, G. H., J. J. Arboleda, and B. L. Travi.  1997.  Dynamics of a population of Didelphis marsupialis in northern Colombia. Studies on Neotropical Fauna and Environment, 32: 7-11.

• ADLER, G. H., and R. P. Beatty.  1997.  Changing reproductive rates in a Neotropical forest rodent, Proechimys semispinosus. Journal of Animal Ecology, 66: 472-480.

• Hoch, G. A., and G. H. ADLER.  1997.  Removal of black palm (Astrocaryum standleyanum) seeds by spiny rats (Proechimys semispinosus). Journal of Tropical Ecology, 13: 51-58.

• ADLER, G. H., and T. D. Lambert.  1997.  Ecological correlates of trap response of a Neotropical forest rodent, Proechimys semispinosus. Journal of Tropical Ecology, 13: 59-68.

• ADLER, G. H., M. Endries, and S. Piotter.  1997.  Spacing patterns within populations of a tropical forest rodent, Proechimys semispinosus, on five Panamanian islands.  Journal of Zoology (London), 241: 43-53.

• ADLER, G. H.  1996.  The island syndrome in isolated populations of a tropical forest rodent.  Oecologia, 108: 694-700.

• ADLER. G. H., and J. O. Seamon.  1996.  Distribution of four-eyed opossums (Philander opossum) on small islands in Panama. Mammalia, 60: 91-99.

• Seamon, J. O., and G. H. ADLER.  1996.  Population performance of generalist and specialist rodents along habitat gradients. Canadian Journal of Zoology, 74: 1130-1139.

• ADLER, G. H.  1996.  Habitat relations of two endemic highland forest rodents in Taiwan.  Zoological Studies, 35: 105-110.

• Dudley, R., and G. H. ADLER.  1996.  Biogeography of milkweed butterflies (Nymphalidae: Danainae) and mimetic patterns on tropical Pacific archipelagos.  Biological Journal of the Linnean Society, 57: 317-326.

• ADLER, G. H.  1995.  Fruit and seed exploitation by Central American spiny rats, Proechimys semispinosus.  Studies on Neotropical Fauna and Environment, 30: 237-244.

• ADLER, G. H., C. C. Austin, and R. Dudley.  1995.  Dispersal and speciation of skinks among archipelagos in the tropical Pacific Ocean. Evolutionary Ecology, 9: 529-541.

• ADLER, G. H. 1995.  Habitat relations within lowland grassland rodent communities in Taiwan.  Journal of Zoology (London), 237: 563-576.

• ADLER, G. H., and R. Levins.  1994.  The island syndrome in rodent populations.  Quarterly Review of Biology, 69: 473-490.

• ADLER, G. H.  1994. Tropical forest fragmentation and isolation promote asynchrony among populations of a frugivorous rodent. Journal of Animal Ecology, 63: 903-911.

• ADLER, G. H. 1994. Avifaunal diversity and endemism on tropical Indian Ocean islands. Journal of Biogeography, 21: 85-95.

• ADLER, G. H., and R. Dudley. 1994. Butterfly biogeography and endemism on tropical Pacific islands. Biological Journal of the Linnean Society, 51: 151-162.

• Levins, R., and G. H. ADLER. 1993. Differential diagnostics of island rodent populations. Coenoses, 8: 131-139.

• ADLER, G. H., S. R. Telford III, M. L. Wilson, and A. Spielman. 1992. Vegetation structure influences the burden of immature Ixodes dammini on its main host, Peromyscus leucopus. Parasitology 105: 105-110.

• ADLER, G. H. 1992. Endemism in birds of tropical Pacific islands. Evolutionary Ecology 6: 296-306.

• Mather, T. N., S. R. Telford III, and G. H. ADLER. 1991. Lack of transplacental transmission of Lyme disease spirochetes from reservoir mice (Peromyscus leucopus) to their offspring.  Journal of Infectious Diseases 164: 564-567.

• ADLER, G. H., and J. O. Seamon. 1991. Distribution and abundance of a tropical rodent, the spiny rat, on islands in Panama. Journal of Tropical Ecology 7: 349-360.

• Schoener, T. W., and G. H. ADLER. 1991. Greater resolution of distributional complementarities by controlling for habitat affinities: a study with Bahamian lizards and birds. American Naturalist 137: 669-692.  *** Featured in "News and Views" by Jared Diamond, Nature 355: 501-502, 6 February 1992***.

• Telford, S. R. III, T. N. Mather, G. H. ADLER, and A. Spielman. 1990. Short-tailed shrews as reservoirs of the agents of Lyme disease and human babesiosis. Journal of Parasitology 76: 681-683.

• Schlinger, B. A., and G. H. ADLER. 1990. A nonparametric aid in identifying sex of cryptically dimorphic birds. Wilson Bulletin 102: 545-550.

• ADLER, G. H., and M. L. Wilson. 1989. Insular distributions of voles and shrews: the rescue effect and implications for species co-occurrence patterns. Coenoses 4:69-72.

• ADLER, G. H., and M. L. Wilson. 1989. Demography of the meadow vole (Microtus pennsylvanicus) along a simple habitat gradient. Canadian Journal of Zoology 67:772-774.

• ADLER, G. H. 1988. The role of habitat structure in organizing small mammal populations and communities. Pages 289-299 in R. C. Szaro, K. E. Severson, and D. R. Patton (editors). Management of amphibians, reptiles, and small mammals in North America.  United States Department of Agriculture Forest Service General Technical Report RM-166.

• Moyer, C. A., G. H. ADLER, and R. H. Tamarin. 1988. Systematics of New England Microtus, with emphasis on Microtus breweri. Journal of Mammalogy 69:782-794.

• ADLER, G. H., M. L. Wilson, and M. J. DeRosa. 1987. Effects of adults on survival and recruitment of Peromyscus leucopus. Canadian Journal of Zoology 65:2519-2523.

• Tamarin, R. H., G. H. ADLER, M. Sheridan, and K. Zwicker. 1987. Similarity of spring population densities of the island beach vole, Microtus breweri, 1972-1986. Canadian Journal of Zoology 65:2039-2041.

• ADLER, G. H., and M. L. Wilson. 1987. Demography of a habitat generalist, the white-footed mouse, in a heterogeneous environment. Ecology 68:1785-1796.

• ADLER, G. H. 1987. Influence of habitat structure on demography of two rodent species in eastern Massachusetts. Canadian Journal of Zoology 65:903-912.

• ADLER, G. H., M. L. Wilson, and M. J. DeRosa. 1986. Influence of island area and isolation on population characteristics of Peromyscus leucopus. Journal of Mammalogy 67:406-409.

• ADLER, G. H., and M. L. Wilson. 1985. Small mammals on Massachusetts islands: the use of probability functions in clarifying biogeographic relationships. Oecologia 66:178-186.

• ADLER, G. H. 1985. Habitat selection and species interactions: an experimental analysis with small mammal populations. Oikos 45:380-390.

• ADLER, G. H., and R. H. Tamarin. 1985. Dispersal in low-density island and mainland white-footed mice. Canadian Field-Naturalist 99:331-336.

• Wilson, M. L., G. H. ADLER, and A. Spielman. 1985. Correlation between abundance of deer and that of the deer tick, Ixodes dammini (Acari: Ixodidae). Annals of the Entomological Society of America 78:172-176.

• Moyer, C. A., G. H. ADLER, and R. H. Tamarin. 1985. Estimating body size of Microtus pennsylvanicus and Microtus breweri using skull and molar measurements. American Midland Naturalist 113:388-389.

• ADLER, G. H., L. M. Reich, and R. H. Tamarin. 1984 Demography of the meadow jumping mouse (Zapus hudsonius) in eastern Massachusetts. American Midland Naturalist 112:387-391.

• ADLER, G. H., L. M. Reich. and R. H. Tamarin. 1984. Characteristics of white-footed mice in woodland and grassland in eastern Massachusetts. Acta Theriologica 25:57-62.

• ADLER, G. H., and R. H. Tamarin. 1984. Demography and reproduction in island and mainland white-footed mice (Peromyscus leucopus) in southeastern Massachusetts. Canadian Journal of Zoology 62:58-64.

Graduate students in The Tropical Rat Lab:

• Donna M. Charley. 1996. Density dependence in the tropics: a statistical analysis of Proechimys semispinosus (spiny rat) populations.  Current position: Lecturer, University of Wisconsin - Oshkosh.

• Thomas D. Lambert.  1999 (with honors).  The effects of tropical forest fragmentation on rodent community structure.  Current position: Doctoral candidate, University of Toronto, Faculty of Forestry.

• Scott A. Mangan.  1999 (with honors).  The consumption of arbuscular mycorrhizal fungi by Neotropical rodents.  Current position: Doctoral candidate, Indiana University, Department of Biology.

• Kelley A. Hoey.  1999.  A systematic study of the genus Proechimys (the spiny rat) using the scanning electron microscope (SEM) to examine the external morphology of spines.  Current position: SEM Technician, Mayo Clinic.

 
• Mark Endries.  2000.  Modeling spacing patterns of a tropical forest rodent using radiotelemetry and geographic information systems (GIS).

• William D. Boyett.  2001.  Habitat use by the endangered Hualapai Mexican vole: implications for conservation.

• Shannon Davis.  2001.  Resource abundance and the demography of a tropical forest rodent.

 
• Michael J. Lohre.  In progress.

Undergraduates in The Tropical Rat Lab:

• Past:  Mark Endries, Shawn Piotter, Ron Beatty, Jennifer Freund, Christina Sample, Rebecca Eder, Rob McKee, Josh LaPointe, Jared Haas, Jake Demelle.

Visiting Scientists in The Tropical Rat Lab:

• Victor Suntsov.  1999.  Senior Scientist, Severtzov Institute of Ecology and Evolution, Russian Academy of Science, Moscow, Russia.

 
• Bruno L. Travi.  2001.  Sub-Director, International Center for Medical Training and Research, Cali, Colombia.

 
• Alejandra Carvajal.  2002.  Universidad del Valle, Cali, Colombia.

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Last updated 25 February 2002.