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Mark Torchin

English
Marine Ecology Invasion Biology Disease Ecology

The tropics are believed to be more resistant to invasive species compared to temperate regions. More native biodiversity results in increased competition, predation and parasitism, which leave fewer opportunities to invade. Is that really the case?

Mark Torchin
STRI Coral Reef

Protistan Biogeography: A Snapshot Across a Major Shipping Corridor Spanning Two Oceans, 2017

Tropical fish community does not recover 45 years after predator introduction, 2017

Pan-NEMO Database

My lab’s research focuses on coastal marine ecology with an emphasis on host-parasite and consumer interactions, infectious diseases and biological invasions. I focus on how trophic interactions such as parasitism and predation alter populations, community structure and ecosystems. Parasites are common in many systems, yet their interactions with free-living communities are often poorly understood. This is particularly true in marine and estuarine environments. The land-sea interface is a region of high productivity and biological diversity, but it is changing at an accelerated pace due to increasing human pressures including biological invasions. This provides both research opportunities as well as urgency for understanding how to manage these ecosystems. My lab is working on biological invasions across tropical and temperate systems developing a global perspective on factors driving invasions. With collaborators around the world, we are developing a latitudinal framework approach to examine factors (a) influencing patterns of marine diversity, (b) driving invasions and (c) facilitating parasite/ disease transmission in coastal regions. My research is at the intersection of biological invasions and parasite/ disease ecology.

What would the world look like without parasites?

Parasites are often considered 'bad' but actually they are a natural part of ecosystems and biological diversity. Parasites control host populations, which prevents hosts from becoming excessively abundant. Parasitism is the most common lifestyle on Earth and it may even promote species coexistence and stabilize ecosystems.

Are the tropics more resistant to marine invaders than the temperate zones?

The idea is that tropical regions and their native biodiversity are better at resisting invasive species than temperate regions due to high biodiversity and strong biotic interactions like predation, parasitism and competition. We are testing this hypothesis by using the same experiments across a latitudinal framework that has not been applied in marine systems. The fundamental goal is to learn how biotic interactions shape invasions and shape the biodiversity of marine communities in general.

What happens when you remove parasites from an ecosystem?

Most people think of parasites and diseases as being detrimental to the overall health of an ecosystem. But researchers are now realizing that parasites and pathogens are consumers that have important roles in ecosystems. When we discuss disease ecology, people tend to focus on emerging diseases or outbreaks in a particular place, not necessarily the underlying infectious processes that connect communities and that might be keeping ecosystems healthy. Parasites and pathogens are normal components of ecosystems and contribute to biodiversity. We are now beginning to ask if it is possible to use parasites to understand fundamental principles in patterns of biodiversity.

Some other research questions

Do native predators and parasites control marine invaders? How do consumer interactions, shape the diversity you see on the rocks in the intertidal zone or on tropical or temperate reefs? Are predators and parasites more important in limiting invasions in the tropics compared to higher latitudes? In other words, are you more likely to get eaten in the tropics than in the temperate zone — whether it’s a by parasite, a predator or something that is taking a little bite like a mosquito or a browser like a deer?

Ph.D., University of California, Santa Barbara, 2002

M.S., University of Oregon, 1994

B.A., University of California, Santa Barbara, 1991

Miura, O., M.E. Torchin, E. Bermingham, D.K. Jacobs, R.F. Hechinger (2012). Flying shells: historical dispersal of marine snails across Central America. Proceedings of the Royal Society of London 279:1061-1067. doi: 10.1098/rspb.2011.1599

Freestone, A.L, R.W. Osman, G.M. Ruiz, M.E. Torchin (2011). Stronger predation in tropics shapes species richness patterns in marine communities. Ecology 92: 983-993.

Roche, D.G., B. Leung, E.F. Mendoza Franco, M.E. Torchin (2010). Higher parasite richness, abundance, and impact in native versus introduced cichlid fishes. International Journal of Parasitology 40:1525–1530

Torchin, M.E. and C.E. Mitchell (2004). Parasites, pathogens and invasions by plants and animals. Frontiers in Ecology and the Environment 2: 183-190.

Torchin, M.E., K.D. Lafferty, A.P. Dobson, V.J. McKenzie, A.M. Kuris (2003). Introduced species and their missing parasites. Nature 421: 628-630. 

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Mark E. Torchin

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Mark

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Torchin

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Staff Scientist
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Global Change
Invasion Biology
Long-term monitoring
Marine Biology
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Ira Rubinoff

English
Marine Biology

Understanding the biodiversity of Planet Earth is the most interesting of human endeavors. Where better to pursue this interest than in the tropics?

Ira Rubinoff
STRI Coral Reef

A century of the Smithsonian Institution on the Isthmus of Panama, 2013

Smithsonian Institution Global Earth Observatories, 2007

As STRI director for 34 years, a lot of innovative things were enabled under my watch. One of the most important was the addition of the five peninsulas to the Barro Colorado Nature Monument, which created a buffer zone around Barro Colorado Island and added research areas that allow for manipulative experiments. Some of the big research accomplishments included the establishment of the 50-hectare forest dynamics plot on Barro Colorado, which led to the Center for Tropical Forest Science and today’s ForestGEO network that has more than 60 plots around the globe. We innovated the use of construction cranes to gain access to the forest canopy for the study of canopy biodiversity and gas exchange between the biosphere and the atmosphere. We also probably opened one of the first, if not the first, molecular lab in the tropics, established a telemetry system to monitor moving organisms in the forest around the clock, and we developed two ocean marine laboratories.

Please note: I no longer advise students. Prospective interns, fellows and postdoctoral researchers should contact STRI’s academic programs office.

Have marine fishes separated by the Isthmus of Panama formed new species?

To answer the question, we examine four species of the fish genus Bathygobius, two species of which are found on the Atlantic coast and two on the Pacific. The differences allopatric species had presumably arisen due to separation of the original common gene pool by the closure of the Isthmus of Panama. By using artificial hybridization experiments and laboratory breeding tests we were able to show that the species on the same side of the Isthmus are completely reproductively separated by pre-mating behavioral isolating mechanisms. The allopatric (transisthmian) species, although now morphologically different, have still not, after 3 million years, evolved complete reproductive isolation, and hybridization in aquaria occurs regularly when presented with no choice of mates or with unbalanced sex ratios of allopatric species.

Could we establish a graduate university at STRI?

I’m currently exploring the possibility of establishing a graduate-level university at STRI that would train students from around the world and allow them to spend their full graduate careers doing research in the tropics. Hundreds of students have completed Ph.D. research at STRI but they are generally required to return to their home institutions for at least a year to complete their doctoral degrees. Establishing a graduate-level university based in the tropics would, in a significant way, help address the global imbalance between the world’s best universities, 94 percent of which are in the temperate zone, and Earth’s biodiversity, 80 percent of which is found in the tropics.

1963 Ph.D., Harvard University, Cambridge, Massachusetts

1961 M.A., Harvard University, Cambridge, Massachusetts

1959 B.S., Queens College, Queens, New York

Rubinoff, Ira. 2013. A Century of the Smithsonian Institution on the Isthmus of Panama. ReVista: Harvard Review of Latin America, 12(3): 62-66.

Rubinoff, Ira; Bermingham, Eldredge; Lydeard, Charles; Davies, Stuart James. 2007. Smithsonian Institution Global Earth Observatories. In: The Full Picture. Geneva: Tudor Rose on Behalf of Group on Earth Observations, pp.82-84.

Rubinoff, Ira; Leigh, Egbert Giles, Jr. 1990. Dealing with Diversity: The Smithsonian Tropical Research Institute and Tropical Biology. Trends in Ecology and Evolution, 5(4): 115-118.

Rubinoff, Ira; Graham, Jeffrey B.; Motta, Jorge. 1986. Diving of the Sea Snake Pelamis platurus in the Gulf of Panamá. I. Dive Depth and Duration. Marine Biology, 91(2): 181-191.

Rubinoff, Ira. 1983. A strategy for preserving tropical forests. In: Sutton, S. L., Tropical Rain Forest: Ecology and Management. Oxford: The British Ecological Society, pp.465-476.

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Ira Rubinoff
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Ira Rubinoff

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David Roubik

English
Evolutionary Ecology Behavioral Ecology Animal Behavior

Each natural community, or assemblage of organisms, has its own analog to an immune system. When humans take charge, they’d better either let nature have its way, or go in with a plan to use the right organisms, in the right way, and at the right time, before the resident community, and all its associated physical entities, terminate it. We, as scientists, are now in the spotlight to show what is ‘right’.

David Roubik
STRI Coral Reef

Orchid bees (Hymenoptera: Apidae: Euglossini) of Cusuco National Park, State of Cortés, Honduras, 2016

An embellishment that became a mutualism: Inquiries on male bee tibial bouquets and fragrance-producing orchids in Panama and oceanic islands (Apidae: Apinae, Euglossini; Orchidaceae: Epidendroideae), 2016.

I’ve gotten used to performing long-term studies, and shorter-term field experiments, but most of all try to mix and match what is both interesting and useful. Many studies have come to fruition, and those I continue to expand consider 1) ecology and taxonomy of stingless bees and orchid bees, 2) island biogeography of bees, and 3) reproduction by dioecious tree species. I joined the Smithsonian in Panama to address an urgent need to predict the impact of Africanized honeybees as they spread north from Brazil. I came from an ecology and taxonomy background. My collaborators and I currently explore how the natural role of bees as pollinators, or as producers of human food and benefits, function and are maintained, even as agro-ecosystems push them around. I edit, write and review many publications, because we are advancing rapidly. There are bright spots — because novel communities are often sustainable — at least from a scientific perspective. I see competition among pollinators as a different kind of paradigm in ecology, because losers win and winners may lose. That is because they are within networks and actually feed one another, and change over time. I try to balance my research with field biology, academic depth, museum research, and applied goals, and have a splendid base for that at STRI.

How are tropical bees agents of connectivity?

Bees, like microbes, live everywhere and interact as parasites, commensals and mutualists. They are not boxes of insects — they are 30,000 species living primarily in the temperate zone, without honey, queen, or castes, solitarily, and do amazing things, including making possible the reproduction of roughly half of all plants. Bees have deep relations with bacteria, fungi and archaea. They are much more likely to be social or make honey, or be present at flowers, in the tropics, where their total species richness is nonetheless much lower than in many warm temperate areas.

How is it that at the peak of social evolution in insects, there are honey and social bee colonies, with a queen, workers and drones, and why is this fact such an important feature among tropical, human societies?

Insect colonies — big ones — need to store fuel, materials, and protein to continue. Their dispersion matters. Their defenses from enemies must be well coordinated. Their need for making the most of stored protein, carbohydrates, etc. involves managing their microbial communities and propagating them through generations. People believe that bee food, including larvae, honey and pollen or ‘bee bread’ and propolis (a resinous mixture of building material) have medicinal value. The chemical, microbiological and botanical components are ripe for further investigation, especially in the tropics. Honey from native vegetation is usually from about 50 plant species, making honey the most biodiverse natural product.

How can we adequately measure the abundance of natural pollinators and decide what to do to better conserve them?

Animal populations never are stable. Surveys of living organisms, like bees or other pollinators, are few and far between, and often do not consider biologically important ‘recent’ events — e.g. periodic El Niño-Southern Oscillation droughts which are highly positively correlated with flowering peaks and bee populations, or heavy rainfall, or human impact. Bee nests are in the soil, in dead branches, in living trees, in tilled land, in urban areas, or in forest. Not all bees are the same, their parasite and predator pressures differ, their reproductive seasons are diverse, in the case of bee colonies, whole-colony reproduction does not occur with a high predictably. We need to make more efforts to fill our knowledge gaps, by making comparative studies.

How can we predict or understand the competition in complex networks like those involving pollinators and plants — which I have termed “silent competition” where there are no clear winners or losers — at least in the short term?

Competition theory never explained much about pollinators. Their interactions are properly defined in networks, in which they are facilitators, competitors or flat-out mutualists, simultaneously. It is a question for integral calculus, not short- or medium-term field experiments (which is the best that I or others can do, for a number of reasons), or based on a simple matrix or network. The Africanized honeybee studied for 17 years pre- and post-invasion in Yucatán gave us a reference point. They caused resource partitioning, and then evidently an expanded resource base, which their competitors benefit from. This is not Lotka-Volterra anymore.

University High School, Minneapolis, Minnesota 1965-69

University of Minnesota, Minneapolis; advanced Spanish 1968-69

Macalester College, Saint Paul, Minnesota; Humanities 1969-71

University of Washington, Seattle; Liberal Arts 1972

BS (entomology) Oregon State University 1975

Ph.D. (entomology) University of Kansas 1979. "Competition Studies of Colonizing Africanized Honey Bees and Native Bees in South America"

Pot-Pollen: Stingless bees in Melittology. (2017). (Editor, with P. Vit and S. R. M. Pedro). Springer, New York.

The Pollination of Cultivated Plants. A Compendium for Practitioners (2017). Editor. FAO, Rome.

Orchid Bees of Tropical America: Biology and Field Guide (with Paul Hanson, 2004). InBio Press, Costa Rica.

Pollen and Spores of Barro Colorado Island. (with Enrique Moreno, 1991). Missouri Botanical Garden, St. Louis.

Ecology and Natural History of Tropical Bees. (1989). Cambridge University Press, New York.

roubikd [at] si.edu
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David W. Roubik
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David Ward Roubik

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David W.

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Roubik
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Global Change
Invasion Biology
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Dolores Piperno

English
Anthropology Archaeobotany Paleoecology

The data win in the end. A multidisciplinary approach to scientific questions and close collaboration with geneticists, plant physiologists and other scholars will piece together a reliable picture of the past.

Dolores Piperno
STRI Coral Reef

Lorant et al The Potential Role of Genetic Assimilation during Maize Domestication PLoS One 12 (9): e0184202.

Piperno, Dolores R. 2017. Assessing elements of an extended evolutionary synthesis for plant domestication and agricultural origin research. Proceedings of the National Academy of Sciences, 114 (25): 6429-6437.

Niche construction and optimal foraging theory in Neotropical agricultural origins: A re-evaluation in consideration of the empirical evidence, 2017

My research interests have mainly involved the archaeology and human ecology of the lowland American tropics together with the biogeographical and climatological history of the tropical biome. They have included study of phytoliths, starch grains and pollen at archeological sites in Panama, Mexico, Ecuador, Peru, and Israel. A primary interest is the origins of agriculture worldwide and an associated current project involves the investigation of teosinte (wild maize) and maize growth and phenotypic (developmental) plasticity in the atmospheric CO2 and temperature conditions in which they were first collected by human populations and cultivated. Phenotypic plasticity, which may be directly induced by developmentally-mediated environmental cues and result in rapid phenotypic divergences in part through changes in gene expression, is a neglected concept in domestication research despite its increasing importance in evolutionary biology. This project will soon incorporate study of wild and domesticated beans (Phaseolus spp.) and squashes (Cucurbita spp.).

Another main focus of current investigation is the impact and legacies of prehistoric human modification on Amazonian forests through phytolith and charcoal studies of terrestrial soils from underneath standing interfluvial and riverine forests in remote areas of the Amazon Basin. This project will also involve large expansions of the Amazonian modern phytolith reference collection so that the numerous currently unknown phytoliths being retrieved from the ancient soils can be identified and employed to reconstruct prehistoric forest management of various types.

When and how did humans domesticate plants, and why did agriculture originate?

The development of agricultural societies made possible by plant and animal domestication was one of the most transformative events in human and ecological history. Independent beginnings of agriculture occurred between 12,000 and 10,000 years ago in a number of world regions, including the American tropics, southwest Asia, and China. Plant domestication was at its core an evolutionary process involving both natural and human selection for traits favorable for harvesting and consumption. Ever-improving analytic methods for retrieving empirical data from archaeological sites, together with advances in genetic, genomic, and experimental research on living crops and their wild ancestors are providing new understandings of, and mechanisms for domestication and early agriculture (see discussion under Research Focus). Scholars have long debated why hunters and gatherers became farmers, a question that will also see increasing understanding.

When, where, and how was the tropical forest exploited and modified by prehistoric cultures?

Prominent scholars once believed that the Neotropical forest vegetation and landscape were little altered by pre-Columbian cultures. It is now known that significant, sometimes profound, human environmental modification of many types (fire, vegetation clearing; depression of preferred prey through over-exploitation; construction of earthworks and roads) has a deep history in the American tropics. However, some regions remain understudied. Still not understood, for example, is when and how a human presence may have modified landscapes across the vast terra firme (interfluvial) forest zone of the Amazon Basin. Multi-proxy analyses of lake sediments and terrestrial soils (e.g., pollen, phytoliths, charcoal) are at once improving our resolution of both natural- and human-cased environmental change in Amazonia and elsewhere, and expanding the types of locations such evidence can be found in.

How can plant microfossils be improved as a discovery tool for paleobotanical history?

Plant microfossils such as phytoliths, starch grains, and pollen can be used to effectively study prehistoric plant exploitation and agriculture. In the Neotropics, many important crops such as maize, squashes, manioc, and yams can be identified. Archaeological materials offering robust contexts for microfossil study now include stone tools, ceramics, sediments, and human teeth. Future research should expand the number of identifiable taxa and refine current identifications, discover more about the types of plant preparation and consumption the microfossils can reveal (e.g., chicha-making?), and add to understanding of their roles in documenting prehistoric plant usage in the Neotropics and elsewhere.

B.S. in Medical Technology, Rutgers University, 1971.

M.A. in Anthropology, Temple University, 1979.

Ph.D.in Anthropology, Temple University, 1983.

(Major advisor: Dr. Anthony Ranere.)

Lorant A, Pederson, S., Holst, I., Hufford, M.B., Winter, K., Piperno, D.R., Ross-Ibarra, J. The potential role of genetic assimilation during maize domestication. PLoS One https://doi.org/10.1371/journal.pone.0184202. 

Piperno, D.R., Ranere, A.J., Dickau, R., Aceituno, F. (2017) Niche construction and optimal foraging theory in Neotropical agricultural origins: A re-evaluation in consideration of the empirical Evidence. Journal of Archaeological Science 78:214-220.

Piperno, D.R., Holst, I., Winter, K., McMillan, O. 2014. Teosinte before domestication: Experimental study of growth and phenotypic variability in Late Pleistocene and early Holocene environments. Quaternary International, doi:10.1016/j.quaint.2013.12.049

Piperno, D.R. 2011. The Origins of Plant Cultivation and Domestication in the New World Tropics: Patterns, Process, and New Developments. In The Beginnings of Agriculture: New Data, New Ideas, edited by D. Price and O. Bar-Yosef. Special Issue of Current Anthropology. Vol 52, No. S4, 453-470.

Piperno, D.R., Ranere, A.J., Holst, I., Iriarte, J., & Dickau, R. 2009. Starch grain and phytolith evidence for early ninth millennium B.P. maize from the Central Balsas River Valley, Mexico. Proceedings of the National Academy of Sciences USA, 106:5019-5024.

Piperno, D.R. Phytoliths: A Comprehensive Guide for Archaeologists and Paleoecologists. 2006. AltaMira Press, Lanham MD.

Piperno, D.R., Ranere, A.J., Holst, I., & Hansell, P. 2000. Starch Grains Reveal Early Root Crop Horticulture in the Panamanian Tropical Forest. Nature, 407:894-897.

Piperno, D.R., & Pearsall, D.M. 1998. The Origins of Agriculture in the Lowland Neotropics. Academic Press, San Diego.

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Dolores R. Piperno

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Global Change
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Robert Stallard

English
Ecology Hydrology

Water passes through vegetation and flows through and over soil, bathing the living Earth. Monitoring water flux and composition of rivers and streams is a powerful tool for understanding natural and anthropogenic change at both local and landscape levels.

Robert Stallard
STRI Coral Reef

Formation of the Isthmus of Panama, 2016 

Que tan Viejo es el Istmo de Panama, 2015

My research focuses on how land-cover and climate change affect water movement through soils, weathering, and erosion, and how these, in turn, affect the composition and dispersal of dissolved and solid phases in rivers and trace gases in the atmosphere. Some of my areas of expertise include surface-water hydrology, major element and nutrient biogeochemistry, soil formation and sediment genesis, vegetation-landscape interaction, carbon-cycle characterization on land and in the ocean, and assessment of land-use and climate change. My work has included the study of natural and human-altered landscapes, in the Americas, Southeast Asia, and Africa, including large parts of the Amazon, Orinoco, Mississippi, and Panama Canal Basins and eastern Puerto Rico. One of my major research projects in Panama is at STRI’s Agua Salud Project in the Central Panama Canal Basin, where we examine the manifold effects of different styles of reforestation as compared to mature forested and deforested catchments. I am working on the foundations of a 20-to-40-year study that will be used to assess hydrologic and biogeochemical processes both at a fine scale and at the scale of the Panama Canal Basin.

What does water reveal about tropical landscapes?

By studying hydrology and biogeochemistry of natural and human-altered landscapes in the Americas, Southeast Asia and Africa, I contribute to new concepts integrating atmospheric and terrestrial processes and the role of people as ecosystem shapers.

How do exceptional phenomena—giant storms to wildfires to volcanic eruptions—affect river composition and flow?

Any process that alters most of a landscape, from construction, to agriculture, to fire alter the way that landscape processes water from rain or snowmelt. These processes usually increase vulnerability to erosion, and a giant storm is able to generate more runoff and mobilize massive amounts of sediment, more than would have been mobilized under its former land cover. The very largest storms, however, can even break through the natural protections afforded by intact land cover, and great erosion can result. Volcanoes are another story. They make their own landscapes, by providing vast quantities of new, abiologic, loose material, by melting summit snow and glaciers to make raging torrents, and by creating their own weather. Rivers become debris flows and lahars; valleys and towns are buried. With the larger eruptions, former landscapes are gone and new cycles of land-cover development, weathering, and erosion must begin again; Krakatao is a famous example.

Are there rules of thumb to reliably assess watershed processes?

An experienced hydrologist or biogeochemist thinks with rules of thumb. How does a new watershed resemble ones that have been previously witnessed and measured in detail? Is this a flatland or a steepland? Is the water turbid? What do quick measurements such as pH and conductivity reveal about the weathering? Today, remote sensing is a fantastic tool, enabling the hydrologist or biogeochemist to develop a three dimensional view of the landscape and upstream land cover to better put a watershed into context. Complicated chemical measurement and hydrologic modeling can then be invoked to refine an analysis, but these are time consuming and expensive. The best field hydrologists and biogeochemists are often those who have studied the most landscapes in the field.

Can we provide inexpensive data for evaluating landscape conservation and mitigation of human impact?

In today’s world, the least expensive data to access and use is often remote sensing – satellite images and digital elevation models. These can be used to put a landscape in context. Basic hydrologic monitoring (rainfall, stream discharge, and basic meteorological data) is essential, and water-quality monitoring (temperature, conductivity, pH, and suspended sediment) incrementally adds to an understanding of human impacts and mitigation work. An in-depth understanding (what, where, when, why, and who?), gained through chemical analyses of sediment, major constituents, nutrients, trace elements, and pesticides can range from relatively inexpensive – a few strategic samples, with sample collection guided by experience elsewhere – to expensive – comprehensive forensic studies.

Can understanding erosion and its coupling to the water cycle inform us about the history of the planet?

Yes, and this has been a life’s interest for me. The Earth’s history is recorded in sedimentary rocks, rocks that have been deposited in the Earth’s surface environment, either under liquid water, air, or ice. There are three major flavors: clastic (deposited as particles), chemical (chemically or biologically precipitated out of material that was in solution), and organic (the accumulated soft parts of plants). Each of these classes of sediments records information about its history of erosion, transport (dispersal), and deposition. Fossils contained within these sediments provides considerable additional information. I am particularly interested in clastic sediments because the first step in their formation is erosion, and this is in turn controlled largely by bedrock composition, topographic relief (flat versus steep), temperature (cold, warm), moisture supply (limited, rain, snow, ice), and land cover. Sorting these controls is one of the enduring themes of my research.

1970-1974, Massachusetts Institute of Technology, B.S. Earth and Planetary Sciences, emphasis in Planetary Physics and Chemistry.

1975-1980, Massachusetts Institute of Technology - Woods Hole Oceanographic Institution Joint Program in Oceanography, Ph.D., emphasis in Chemical Oceanography, with a thesis entitled "Major Element Geochemistry of the Amazon River System."

1980-1981, USGS-GD-Office of Marine Geology, Woods Hole, MA, National Research Council Post Doctoral Fellowship, research project on clay mineralogy.

Stallard, R.F., and Murphy, S.F., 2013, A unified assessment of hydrological and biogeochemical responses in research watersheds in eastern Puerto Rico using runoff-concentration relations: Aquatic Chemistry, in press. 

Ogden, F.L., and Stallard, R.F., 2013, Land use effects on ecosystem service provisioning in tropical watersheds, still an important unsolved problem. Proceedings of the National Academy of Sciences, Digital Comment, in press.

Ogden, F.L., Crouch, T.D., Stallard, R.F., and Hall, J.S., 2013, Effect of land cover and use on dry-season river runoff, runoff efficiency and peak storm runoff in the seasonal tropics of central Panama: Water Resources Research, in press.

Coates, A.G., and Stallard R.F., 2013, How old is the Isthmus of Panama? Bulletin of Marine Science, v. 89, n. 3 p.000-000. http://dx.doi.org/10.5343/bms.2012.1076.

Stallard, R.F., 2012, Geology, hydrology, and soils, in Pitman, N., Ruelas I., E., Alvira, D., Vriesendorp, C., Moskovits, D.K., del Campo, Á., Wachter, T., Stotz, D.F., Noningo S., S., Tuesta C., and Smith, R.C., Perú: Cerros de Kampankis: Chicago, Illinois, The Field Museum, Rapid Biological and Social Inventories Report 24, p. 233-242, 318-319, 452 p. [also in Spanish: Geología, hidrología y suelos, p. 76-86, 318-319].

Stallard, R.F., and Murphy, S.F., 2012, Water quality and mass transport in four watersheds in eastern Puerto Rico—Chapter E, in Murphy, S.F., and Stallard, R.F., Editors, Water quality and landscape processes of four watersheds in eastern Puerto Rico: Reston, VA, U. S. Geological Survey, USGS Professional Paper 1789–E, p. 113-152, 292 p. http://pubs.usgs.gov/pp/1789/pdfs/ChapterE.pdf.

Stallard, R.F., 2012, Weathering, landscape equilibrium, and carbon in four watersheds in eastern Puerto Rico—Chapter H, in Murphy, S.F., and Stallard, R.F. , Editors, Water quality and landscape processes of four watersheds in eastern Puerto Rico: Reston, VA, U. S. Geological Survey, USGS Professional Paper 1789–H, p. 199-248, 292 p. http://pubs.usgs.gov/pp/1789/pdfs/ChapterH.pdf.

Stallard, R.F., 2012, Atmospheric inputs to watersheds of the Luquillo Mountains in eastern Puerto Rico—Chapter D, in Murphy, S.F., and Stallard, R.F., Editors, Water quality and landscape processes of four watersheds in eastern Puerto Rico: Reston, VA, U. S. Geological Survey, USGS Professional Paper 1789–D, p. 85-112, 292 p. http://pubs.usgs.gov/pp/1789/pdfs/ChapterD.pdf.

Stallard, R.F., 2011, Landscape processes: geology, hydrology, and soils, in Pitman, N., Vriesendorp, C., Moskovits, D.K., von May, R., Alvira, D., Wachter, T., Stotz, D.F., and del Campo, Á., editors, Perú: Yaguas-Cotuhé: Chicago, Illinois, The Field Museum, Rapid Biological and Social Inventories Report 23, p. 199-210, 272-275, 376 pages. [also in Spanish: Procesos paisajísticos: geología, hidrología y suelos, p. 72-86, 272-275].

Stallard, R.F., Ogden, F.L., Elsenbeer, H., and Hall, J., 2010, Panama Canal Watershed Experiment: Agua Salud Project: Water Resources Impact, v. 12, no. 4, p. 17-20.

Ogden, F.L., Stallard, R.F., Elsenbeer, H., and Hall, J., 2010, Panama Canal Watershed Experiment - Agua Salud Project, in Tarté, A., Soto, E.R., and Messina, E.A., editors, Second International Symposium on Building Knowledge Bridges for a Sustainable Water Future: Panama, Republic of Panama, Panama Canal Authority and UNESCO, p. 168-172.

Stallard, R. F., 1998, Terrestrial sedimentation and the carbon cycle: Coupling weathering and erosion to carbon burial: Global Biogeochemical Cycles, v. 12, no. 2, p. 231-252. 

Stallard, R. F., 1995, Relating chemical and physical erosion: in White, A.F., and Brantley, S.L. eds., Chemical Weathering Rates of Silicate Minerals: Reviews in Mineralogy, v. 31, p.543-564.

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Robert Stallard
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Scientist Type: 
Affiliate Staff Scientists

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Robert

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Stallard
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Bioinformatics
Ecosystem Services
Global Change
Long-term monitoring
Physical Monitoring
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Staff scientists

Owen McMillan

English
Molecular Genetics and Genomics Evolutionary Biology Biodiversity

I am broadly interested in the origins and genetic basis of adaptive variation. This variation is often the product of natural selection. Identifying it and understanding how it works represent both the challenge and promise of modern biology.

Owen McMillan
STRI Coral Reef

Facultative pupal mating in Heliconius erato: implications for mate choice, female preference and speciation. Ecology and Evolution, 8(3):1882-1889.

Macro-evolutionary shifts of WntA function potentiate butterfly wing pattern diversity, Proceedings of the National Academy of Sciences USA, 114 (40):10701-10706.

Complex modular architecture around a simple toolkit of wing pattern genes. Nature Ecology and Evolution, 1:0052.

Gamboa Heliconius

I am broadly interested in the genetics of adaptation and speciation. How do new species form? How does adaptive variation arise and spread? How is morphological variation created through development and modified by natural selection? Is evolution predictable?

The focus of my lab’s research in recent years has been the convergent evolution of wing pattern development in Heliconius butterflies (for which my lab contributed to sequencing the entire genome) throughout the New World tropics. In addition to broad geographic sampling of butterflies, my research group also maintains populations of various species of Heliconius in insectaries in Gamboa, Panama, that can be used for experimental crosses.

As Dean of Academic programs, I oversee STRI’s large group of visiting scholars who number 800 every year, hail from dozens of countries and research institutions, and range in expertise from interns to postdoctoral fellows.

How do differences between organisms arise and spread?

My research leverages genomic technologies to identify functionally important regions of the genome. Recent research has focused on the evolution of wing patterns in Heliconius butterflies. The enormous wing pattern variation in the group offers exceptional opportunities for genomic level studies designed to reveal how morphological variation is created through development and modified by natural selection within the context of an extraordinary adaptive radiation. I maintain an active molecular genetic lab, as well as experimental facilities for Heliconius culture and study.

Duke University, Zoology, B.Sc., 1985

University of Hawaii, Zoology, M.Sc., 1991

University of Hawaii, Zoology, Ph.D., 1994

University College London, Genetics, Postdoctoral, 1994-1997

Hench, K., M. Helmkampf, W. O. McMillan, and O. Puebla.  (2022) Rapid radiation in a highly diverse marine environment. Proceedings of the National Academy of Sciences 119 (4): e2020457119.

Livraghi, L., J. J. Hanly, S. M. Van Bellghem, G. Montejo-Kovacevich, E. van Der Heijden, L. S. Loh, A. Ren, I. A. Warren, J. J. Lewis, C. Concha, L. Hebberecht, C. J. Wright, J. M. Walker, J. Foley, Z. H. Goldberg, H. Arenas-Castro, C. Salazar, M. Perry, R. Papa, A.  Martin, W. O. McMillan*, and C. D. Jiggins*.  (2021)  Cortex cis-regulatory switches establish scale colour identity and pattern diversity in Heliconius. Elife, 10: https://doi.org/10.7554/eLife.68549.

Rossi, M., T. J. Thurman, A. E. Hausmann, S. H. Montgomery, R. Papa, C. D. Jiggins, W. O McMillan, and R. M. Merrill.  (2021)  Visual mate preference evolution during butterfly speciation is linked to neural processing genes.  Nature Communications, 11(1).1-10.

Thurman, T.*, E. Brodie*, E. Evans and W. O. McMillan. (2018) Facultative pupal mating in Heliconius erato: implications for mate choice, female preference and speciation. Ecology and Evolution, 8(3):1882-1889.

Mazo-Vargas, A., C. Concha, L. Livraghi, D. Massardo, W. R. Wallbank, L. Zhang, J. Papador, D. Martinez-Najera, C. D. Jiggins, M. R. Kronforst, C. J. Breuker, R. D. Reed, N. H Patel, W. O. McMillan and A. Martin. (2017) Macro-evolutionary shifts of WntA function potentiate butterfly wing pattern diversity, Proceedings of the National Academy of Sciences USA, 114 (40):10701-10706.

Van Belleghem, S. M., P. Rastas, A. Papanicolaou, S. H. Martin, J. J. Hanly, J. Mallet, J. J. Lewis, H. M. Hines, M. Ruiz, G. R. P. Moreira, C. D. Jiggins, B. A. Counterman*, W. O. McMillan* and R. Papa*. (2017) Complex modular architecture around a simple toolkit of wing pattern genes. Nature Ecology and Evolution, 1:0052.

Nadeau, N. J., C. Pardo-Diaz, A. Wibley, M. Supple, R. Wallbank, G. Wu, L. Maroja, L. Ferguson, H. Hines, C. Salazar, R. J. Tetley, S. Carl, R. ffrench-Constant, M. Joron, W. O. McMillan and C. D. Jiggins. (2016) The origins of a novel butterfly wing patterning gene from within a family of conserved cell cycle regulators. Nature 534(7605): 106–110. doi:10.1038/nature17961.

Supple, M. A., R. Papa, B. A. Counterman and W. Owen McMillan (2013) The genomics of an adaptive radiation– insights across the Heliconius speciation continuum. In Ecological Genomics, 249-271. Landry, C.R. and Aubin-Horth, N. (Eds). Springer.

Supple, M. A., H. M. Hines, K. K. Dasmahapatra, D. M. Nielsen, C. Lavoie, D. A. Ray, C. Salazar, W. O. McMillan*, and B. A. Counterman* (2013) Genomic architecture of adaptive color pattern divergence and convergence in Heliconius butterflies. Genome Research, 23:1248-1257.

Martin, A., R. Papa, N. J. Nadeau, R. I. Hill, B. A.Counterman, G. Halder, C. D. Jiggins, M. R. Kronforst, A Long, W. O. McMillan*, and R. D. Reed* (2012) Diversification of complex butterfly wing patterns by repeated regulator evolution of WntA. Proceedings of the National Academy of Sciences USA, 109(31):12632-12637.

Puebla, O., Bermingham, E., and W. O. McMillan (2012) On the spatial scale of dispersal in coral reef fishes. Molecular Ecology, 21:5675-5688

The Heliconius Genome Consortium (2012) Heliconius butterfly genome reveals promiscuous exchange of adaptive genetic variation among species. Nature, 487(7405): 94-98.

Hines, H. M., B. A. Counterman, R. Papa, P. Albuquerque de Moura, M. Z. Cardoso, M. Linares, J. Mallet, R. D. Reed, C. D. Jiggins, M. R. Kronforst, and W. O. McMillan (2011) Wing patterning gene redefines the mimetic history of Heliconius butterflies. Proceedings of the National Academy of Sciences USA, 118(49): 19666-19671.

Reed, R. D.*, R. Papa*, A. Martin, H. M. Hines, B. A. Counterman, C. Pardo-Diaz, C. D. Jiggins, N. L. Chamberlain, M. R. Kronforst, R. Chen, G. Halder, H. F. Nijhout, and W. O. McMillan (2011) optixs drives repeated convergent evolution in butterfly color pattern mimicry. Science, 333: 1137-1141

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Owen McMillan
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Owen

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McMillan

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Evolutionary Ecology
Developmental Biology
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Staff scientists

Sean McMahon

English
Ecology

The most exciting component of the temperate program in ForestGEO is the extended network of scientists who bring expertise in numerous fields to bear on the important challenges facing Earth’s forest systems.

Sean McMahon
STRI Coral Reef

Tree circumference dynamics in four forests characterized using automated dendrometer bands

CTFS-ForestGEO: a worldwide network monitoring forests in an era of global change, 2015

ForestGeo Vertebrates Program

My primary research focuses on the ecological mechanisms that structure forest communities and determine their fine- and large-scale spatial and temporal dynamics. This research spans topics as diverse as forest demography, functional traits, canopy structure and change over succession, spatial patterns and shifts of temperate and tropical forest tree species, and how climate change influences biomass shifts over stand development. The work combines field research, advanced statistical analyses, computer simulations, and enjoys the collaboration of a global network of scientists in forest ecology, statistics, computer science, and climate science.

The ForestGEO network of forest plots has long offered forest scientists an important way to test whether local observed patterns reflect global processes. The temperate forest plots extend this program to critical biomes that show high-biomass and high growth, and many of the spatial and temporal patterns observed in tropical forests, all with many fewer species. Further, most temperate forests have a long history of human influence, both directly and indirectly, and their study offers critical information about how natural systems can be affected by and respond to human influence.

University of Tennessee, Knoxville. Ph.D. Ecology and Evolutionary Biology. 2007.

University of Tennessee, Knoxville. M.S. Statistics 2006

University College Dublin M.A. in English Literature. 1993

University of Texas, Austin. B.A. in Honors Liberal Arts. 1992

Chang-Yang, Chia-Hao, Needham, Jessica, Lu, Chia-Ling, Hsieh, Chang-Fu, Sun, I-Fang and McMahon, Sean M. (2021). Closing the life cycle of forest trees: The difficult dynamics of seedling-to-sapling transitions in a subtropical rainforest. Journal of Ecology, https://doi.org/10.1111/1365-2745.13677

Chitra-Tarak, Rutuja, Xu, Chonggang, Aguilar, Salomon, Anderson-Teixeira, Kristina J., Chambers, Jeff, Detto, Matteo, Faybishenko, Boris, Fisher, Rosie A., Knox, Ryan G., Koven, Charles D., Kueppers, Lara M., Kunert, Nobert, Kupers, Stefan J., McDowell, Nate G., Newman, Brent D., Paton, Steven R., Perez, Rolando, Ruiz, Laurent, Sack, Lawren, Warren, Jeffrey M., Wolfe, Brett T., Wright, Cynthia, Wright, S. Joseph, Zailaa, Joseph and McMahon, Sean M. (2021). Hydraulically-vulnerable trees survive on deep-water access during droughts in a tropical forest. New Phytologist, https://doi.org/10.1111/nph.17464

Davies, Stuart J., Abiem, Iveren, Abu Salim, Kamariah, Aguilar, Salomon, Allen, David, Alonso, Alfonso, Anderson-Teixeira, Kristina J., Andrade, Ana, Arellano, Gabriel, Ashton, Peter S., Baker, Patrick J., Baker, Matthew E., Baltzer, Jennifer L., Basset, Yves, Bissiengou, Pulcherie, Bohlman, Stephanie, Bourg, Norman A., Brockelman, Warren Y., Bunyavejchewin, Sarayudh, Burslem, David F. R. P., Cao, Min, Cardenas, Dairon, Chang, Li-Wan, Chang-Yang, Chia-Hao, Chao, Kuo-Jung, et al. (2021). ForestGEO: Understanding forest diversity and dynamics through a global observatory network. Biological Conservation, 253 , 108907-108907. https://doi.org/10.1016/j.biocon.2020.108907

Poyatos, Rafael, Granda, Victor, Flo, Victor, Adams, Mark A., Adorjan, Balazs, Aguade, David, Aidar, Marcos P. M., Allen, Scott, Susana Alvarado-Barrientos, M., Anderson-Teixeira, Kristina J., Aparecido, Luiza Maria, Arain, M. Altaf, Aranda, Ismael, Asbjornsen, Heidi, Baxter, Robert, Beamesderfer, Eric, Berry, Z. Carter, Berveiller, Daniel, Blakely, Bethany, Boggs, Johnny, Bohrer, Gil, Bolstad, Paul, V., Bonal, Damien, Bracho, Rosvel, Brito, Patricia, et al. (2021). Global transpiration data from sap flow measurements: the SAPFLUXNET database. Earth System Science Data, 13 (6) , 2607-2649. https://doi.org/10.5194/essd-13-2607-2021

Sedio, Brian E., Spasojevic, Marko J., Myers, Jonathan A., Wright, S. Joseph, Person, Maria D., Chandrasekaran, Hamssika, Dwenger, Jack H., Prechi, Maria Laura, Lopez, Christian A., Allen, David N., Anderson-Teixeira, Kristina J., Baltzer, Jennifer L., Bourg, Norman A., Castillo, Buck T., Day, Nicola J., Dewald-Wang, Emily, Dick, Christopher W., James, Timothy Y., Kueneman, Jordan G., LaManna, Joseph, Lutz, James A., McGregor, Ian R., McMahon, Sean M., Parker, Geoffrey G., Parker, John D., et al. (2021). Chemical Similarity of Co-occurring Trees Decreases With Precipitation and Temperature in North American Forests. Frontiers in Ecology and Evolution, 9 https://doi.org/10.3389/fevo.2021.679638

Fung, Tak, Chisholm, Ryan A., Anderson-Teixeira, Kristina J., Bourg, Norm, Brockelman, Warren Y., Bunyavejchewin, Sarayudh, Chang‐Yang, Chia-Hao, Chitra‐Tarak, Rutuja, Chuyong, George, Condit, Richard, Dattaraja, Handanakere S., Davies, Stuart J., Ewango, Corneille E. N., Fewless, Gary, Fletcher, Christine, Gunatilleke, C. V. S., Gunatilleke, I. A. U. N., Hao, Zhanqing, Hogan, J. A., Howe, Robert, Hsieh, Chang-Fu, Kenfack, David, Lin, YiChing, Ma, Keping, Makana, Jean-Remy, et al. (2020). Temporal population variability in local forest communities has mixed effects on tree species richness across a latitudinal gradient . Ecology Letters, 23 (1) , 160-171. https://doi.org/10.1111/ele.13412

Russo, Sabrina E., McMahon, Sean M., Detto, Matteo, Ledder, Glenn, Wright, S. Joseph, Condit, Richard S., Davies, Stuart J., Ashton, Peter S., Bunyavejchewin, Sarayudh, Chang-Yang, Chia-Hao, Ediriweera, Sisira, Ewango, Corneille E. N., Fletcher, Christine, Foster, Robin B., Gunatilleke, C. V. Savi, Gunatilleke, I. A. U. Nimal, Hart, Terese, Hsieh, Chang-Fu, Hubbell, Stephen P., Itoh, Akira, Kassim, Abdul Rahman, Leong, Yao Tze, Lin, Yi Ching, Makana, Jean-Remy, Mohamad, Mohizah Bt, et al. (2020). The interspecific growth-mortality trade-off is not a general framework for tropical forest community structure. Nature Ecology & Evolution, https://doi.org/10.1038/s41559-020-01340-9

Walker, Anthony P., De Kauwe, Martin G., Bastos, Ana, Belmecheri, Soumaya, Georgiou, Katerina, Keeling, Ralph, McMahon, Sean M., Medlyn, Belinda E., Moore, David J. P., Norby, Richard J., Zaehle, Sönke, Anderson-Teixeira, Kristina J., Battipaglia, Giovanna, Brienen, Roel J. W., Cabugao, Kristine G., Cailleret, Maxime, Campbell, Elliott, Canadell, Josep, Ciais, Philippe, Craig, Matthew E., Ellsworth, David, Farquhar, Graham, Fatichi, Simone, Fisher, Joshua B., Frank, David, et al. (2020). Integrating the evidence for a terrestrial carbon sink caused by increasing atmospheric CO2 . The New Phytologist, https://doi.org/10.1111/nph.16866

Walker, Anthony P., De Kauwe, Martin G., Bastos, Ana, Belmecheri, Soumaya, Georgiou, Katerina, Keeling, Ralph, McMahon, Sean M., Medlyn, Belinda E., Moore, David J. P., Norby, Richard J., Zaehle, Sönke, Anderson‐Teixeira, Kristina J., Battipaglia, Giovanna, Brienen, Roel J. W., Cabugao, Kristine G., Cailleret, Maxime, Campbell, Elliott, Canadell, Josep, Ciais, Philippe, Craig, Matthew E., Ellsworth, David, Farquhar, Graham, Fatichi, Simone, Fisher, Joshua B., Frank, David, et al. (2020). Integrating the evidence for a terrestrial carbon sink caused by increasing atmospheric CO 2 . New Phytologist, https://doi.org/10.1111/nph.16866

Albert, Loren P., Restrepo-Coupe, Natalia, Smith, Marielle N., Wu, Jin, Chavana-Bryant, Cecilia, Prohaska, Neill, Taylor, Tyeen C., Martins, Giordane A., Ciais, Philippe, Mao, Jiafu, Arain, M. A., Li, Wei, Shi, Xiaoying, Ricciuto, Daniel M., Huxman, Travis E., McMahon, Sean M. and Saleska, Scott R. (2019). Cryptic phenology in plants: case studies, implications and recommendations . Global Change Biology, 25 (11) , 3591-3608. https://doi.org/10.1111/gcb.14759

Briscoe, Natalie J., Elith, Jane, Salguero-Gómez, Roberto, Lahoz-Monfort, Jos, Camac, James S., Giljohann, Katherine M., Holden, Matthew H., Hradsky, Bronwyn A., Kearney, Michael R., McMahon, Sean M., Phillips, Ben L., Regan, Tracey J., Rhodes, Jonathan R., Vesk, Peter A., Wintle, Brendan A., Yen, Jian D. L. and Guillera-Arroita, Gurutzeta. (2019). Forecasting species range dynamics with process-explicit models: matching methods to applications . Ecology Letters, 22 (11) , 1940-1956. https://doi.org/10.1111/ele.13348

Fung, Tak, Chisholm, Ryan A., Anderson-Teixeira, Kristina, Bourg, Norm, Brockelman, Warren Y., Bunyavejchewin, Sarayudh, Chang-Yang, Chia-Hao, Chitra-Tarak, Rutuja, Chuyong, George, Condit, Richard, Dattaraja, Handanakere S., Davies, Stuart J., Ewango, Corneille E. N., Fewless, Gary, Fletcher, Christine, Gunatilleke, C. V. Savitri, Gunatilleke, I. A. U. Nimal, Hao, Zhanqing, Hogan, J. Aaron, Howe, Robert, Hsieh, Chang-Fu, Kenfack, David, Lin, YiChing, Ma, Keping, Makana, Jean-Remy, et al. (2019). Temporal population variability in local forest communities has mixed effects on tree species richness across a latitudinal gradient . Ecology Letters, https://doi.org/10.1111/ele.13412

Hogan, J. Aaron, McMahon, Sean M., Buzzard, Vanessa, Michaletz, Sean T., Enquist, Brian J., Thompson, Jill, Swenson, Nathan G. and Zimmerman, Jess K. (2019). Drought and the interannual variability of stem growth in an aseasonal, everwet forest. Biotropica, 51 (2) , 139-154. https://doi.org/10.1111/btp.12624

McMahon, Sean M., Arellano, Gabriel and Davies, Stuart J. (2019). The importance and challenges of detecting changes in forest mortality rates . Ecosphere, 10 (2) , 1-10. https://doi.org/10.1002/ecs2.2615

Smith, Marielle N., Stark, Scott C., Taylor, Tyeen C., Ferreira, Mauricio L., Oliveira, Eronaldo de, Restrepo‐Coupe, Natalia, Chen, Shuli, Woodcock, Tara, dos Santos, Darlisson Bentes, Alves, Luciana F., Figueira, Michela, de Camargo, Plinio B., de Oliveira, Raimundo C., Aragão, Luiz E. O. C., Falk, Donald A., McMahon, Sean M., Huxman, Travis E. and Saleska, Scott R. (2019). Seasonal and drought related changes in leaf area profiles depend on height and light environment in an Amazon forest . New Phytologist, 222 (3) , 1284-1297. https://doi.org/10.1111/nph.15726

Needham, Jessica, Merow, Cory, Chang-Yang, Chia, Caswell, Hal and McMahon, Sean M. (2018). Inferring forest fate from demographic data: from vital rates to population dynamic models. Proceedings of the Royal Society B: Biological Sciences, 285 (1874) https://doi.org/10.1098/rspb.2017.2050

Sedio, Brian E., Parker, John D., McMahon, Sean M. and Wright, S. Joseph. (2018). Comparative foliar metabolomics of a tropical and a temperate forest community . Ecology, 99 (12) , 2647-2653. https://doi.org/10.1002/ecy.2533

Taylor, Tyeen C., McMahon, Sean M., Smith, Marielle N., Boyle, Brad, Violle, Cyrille, van Haren, Joost, Simova, Irena, Meir, Patrick, Ferreira, Leandro V., de Camargo, Plinio B., da Costa, Antonio C. L., Enquist, Brian J. and Saleska, Scott R. (2018). Isoprene emission structures tropical tree biogeography and community assembly responses to climate. New Phytologist, 220 (2) , 435-446. https://doi.org/10.1111/nph.15304

LaManna, Joseph A., Mangan, Scott A., Alonso, Alfonso, Bourg, Norman A., Brockelman, Warren Y., Bunyavejchewin, Sarayudh, Chang, Li-Wan, Chiang, Jyh-Min, Chuyong, George B., Clay, Keith, Condit, Richard S., Cordell, Susan, Davies, Stuart J., Furniss, Tucker J., Giardina, Christian P., Gunatilleke, I. A. U. Nimal, Gunatilleke, C. V. Savitri, He, Fangliang, Howe, Robert W., Hubbell, Stephen P., Hsieh, Chang-Fu, Inman-Narahari, Faith M., Janik, David, Johnson, Daniel J., Kenfack, David, et al. (2017). Plant diversity increases with the strength of negative density dependence at the global scale . Science, 356 (6345) , 1389-1392. https://doi.org/10.1126/science.aam5678

Evans, Margaret, Merow, Cory, Record, Sydne, McMahon, Sean M. and Enquist, Brian J. (2016). Towards Process-based Range Modeling of Many Species. Trends in Ecology & Evolution, 31 (11) , 860-871. https://doi.org/10.1016/j.tree.2016.08.005

Griffith, Alden B., Salguero-Gómez, Roberto, Merow, Cory and McMahon, Sean. (2016). Demography beyond the population. Journal of Ecology, 104 (2) , 271-280. https://doi.org/10.1111/1365-2745.12547

Herrmann, Valentine, McMahon, Sean M., Detto, Matteo, Lutz, James A., Davies, Stuart James, Chang-Yang, Chia and Anderson-Teixeira, Kristina J. (2016). Tree Circumference Dynamics in Four Forests Characterized Using Automated Dendrometer Bands . Plos One, 11 (12) , 1-20. https://doi.org/10.1371/journal.pone.0169020

Janík, David, Král, Kamil, Adam, Dusan, Hort, Libor, Samonil, Pavel, Unar, Pavel, Vrska, Tomás and McMahon, Sean. (2016). Tree spatial patterns of Fagus sylvatica expansion over 37 years. Forest Ecology and Management, 375 , 134-145. https://doi.org/10.1016/j.foreco.2016.05.017

Král, Kamil, Shue, Jessica, Vrška, Tomáš, Gonzalez-Akre, Erika, Parker, Geoffrey G., McShea, William J. and McMahon, Sean M. (2016). Fine-scale patch mosaic of developmental stages in Northeast American secondary temperate forests: the European perspective . European Journal of Forest Research, 135 (5) , 981-996. https://doi.org/10.1007/s10342-016-0988-1

Needham, Jessica, Merow, Cory, Butt, Nathalie, Malhi, Yadvinder, Marthews, Toby R., Morecroft, Michael and McMahon, Sean M. (2016). Forest community response to invasive pathogens: the case of ash dieback in a British woodland. Journal of Ecology, 104 (2) , 315-330. https://doi.org/10.1111/1365-2745.12545

Anderson-Teixeira, Kristina J., Davies, Stuart James, Bennett, Amy C., Gonzalez-Akre, Erika, Muller-Landau, Helene C., Wright, S. Joseph, Abu Salim, Kamariah, Almeyda Zambrano, Angélica M., Alonso, Alfonso, Baltzer, Jennifer L., Basset, Yves, Bourg, Norman A., Broadbent, Eben N., Brockelman, Warren Y., Bunyavejchewin, Sarayudh, Burslem, David F. R. P., Butt, Nathalie, Cao, Min, Cardenas, Dairon, Chuyong, George B., Clay, Keith, Cordell, Susan, Dattaraja, Handanakere S., Deng, Xiaobao, Detto, Matteo, et al. (2015). CTFS-ForestGEO: a worldwide network monitoring forests in an era of global change . Global Change Biology, 21 (2) , 528-549. https://doi.org/10.1111/gcb.12712

mcmahons [at] si.edu
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Sean McMahon
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Scientist Type: 
Affiliate Staff Scientists

Name

Sean

Last name

McMahon
Discipline (Private): 
Long-term monitoring
Department: 
Staff scientists

Harilaos Lessios

English
Ecology Marine Biology

There are millions of species in the oceans. How did they come to be? Although we seek general rules, the answer may lie in the detailed biology of each group.

Harilaos Lessios
STRI Coral Reef

Hiller, A. and H. A. Lessios. 2017. Phylogeography of Petrolisthes armatus, an invasive species with low dispersal ability. Scientific Reports 7: 3359. 10.1038/s41598-017- 03410-8

Gene Flow in Coral Reef Organisms of the Tropical Eastern Pacific, 2016

The Great Diadema antillarum Die-Off: 30 Years Later, 2016

I am interested in the evolution and the ecology of marine organisms, particularly sea urchins, but also fishes, crustaceans, and corals. I focus on the processes that give rise to new species, and I use molecular tools to reconstruct the history of populations and of genes. Typically, this involves reconstructing the trajectories of population genetic and phylogenetic processes in relation to geographic distributions of populations, followed by the assessment of barriers (ecological or molecular) that maintain the genetic integrity of sympatric species. In this effort, I have been greatly aided by the history of the Isthmus of Panama, which separated inhabitants of two oceans at a known time.

How do new species arise and maintain their integrity?

Species generally arise when gene flow is disrupted by a geological or oceanographic barrier. When species come in contact again, they will not merge if they have evolved differences that prevent the transfer of genes. Examples in marine organisms might be specialization in different habitats, difference in spawning cycles, incompatibility of gametes, or developmental dysfunction of hybrids.

What molecules confer compatibility of gametes of the same species and incompatibility between gametes of different species?

We focus on sea urchins (model organisms for developmental biology), because their external fertilization greatly simplifies the number of factors that need to be taken into account. My colleagues and I are studying the evolution of bindin, a molecule on the sperm that is recognized by the egg, and EBR1 and the “350kD protein”, two molecules on the egg that interact with bindin to effect fertilization. To a lesser extent, we have also worked with speract, a molecule released by the egg to attract sperm, as well as its receptor on the sperm.

What are the evolutionary forces that result in barriers to genetic exchange between species?

Species are sets of populations reproductively isolated from other populations, so speciation is the evolution of barriers to genetic exchange. Such barriers need not be molecular interactions of gametes. A long-term study of two genera of sea urchins each with two sympatric sister species in the Caribbean is seeking to establish whether these species occupy different habitats, whether they reproduce at different times (and the factors that control their reproduction), whether their gametes are incompatible, or whether their hybrids are developmentally unstable (and the genes responsible for their lower fitness).

B.A., Harvard College, 1973

M.Phil., Yale University, 1976

Ph.D., Yale University, 1979

H.L. Lessios and G. Hendler. 2022. Mitochondrial phylogeny of the brittle star Genus Ophioderma. Nature Scientific Reports 2022. 12:5304. doi.org/10.1038/s41598-022-08944-0

S.E. Coppard, H. Jessop, H.A. Lessios.  2021. Phylogeography of the sea urchin genus Echinothrix: patterns of dispersal, connectivity, colouration and cryptic speciation across the Indo-Pacific. Nature Scientific Reports 22:26568. doi.org/10.1038/s41598-021-95872-0

T.J. Carrier, H.A. Lessios, A. M. Reitzel. 2020c. Eggs of echinoids separated by the Isthmus of Panama harbor divergent microbiota. Marine Ecology Progress Series. 648:169-177. doi.org/10.3354/meps13424

L. Geyer and H.A. Lessios. 2020b. Slow evolution under purifying selection in the gamete recognition protein bindin of the sea urchin Diadema.  Nature Scientific Reports. 10:9834 DOI:101038/s41598-020-66390-2

A. Hiller and H.A. Lessios. 2019d. Marine species formation along the rise of Central America: The anomuran crab Megalobrachium Molecular Ecology 29:413-428. DOI: 10.1111/mec.15323

N. Mongiardino Koch, S. Coppard, H.A. Lessios, D. Briggs, R. Mooi, G. Rouse.  2018b A phylogenomic resolution of the sea urchin tree of life.  BMC Evolutionary Biology (2018) 18:189 doi.org/10.1186/s12862-018-1300-4

H. A. Lessios and I. Baums.  2017a. Gene flow in coral reef organisms of the tropical eastern Pacific. In: P.W. Glynn, I.C. Enochs, and D. Manzello (eds.) pp. 477-499 In: Coral Reefs of the Eastern Pacific. Springer-Verlag. DOI: 10.1007/978-94-017-7499-4_16

A. O’Dea, H. A. Lessios, A.G. Coates, R.I. Eytan, L.S. Collins, A.L. Cione, A. de Queiroz, D.W. Farris, R.D. Norris, S.A. Restrepo-Moreno, R.F. Stallard, M.O. Woodburne, O.Aguilera, M.-P. Aubry, W.A. Berggren, A.F. Budd, M.A. Cozzuol, S.E. Coppard, H.Duque-Caro, S.Finnegan, G.M. Gasparini, E.L. Grossman, K.G. Johnson, L.D. Keigwin, N.Knowlton, E.G. Leigh, J.S. Leonard-Pingel, P.B. Marko, N.D. Pyenson, P.G. Rachello-Dolmen, E.Soibelzon, L. Soibelzon, J.A.Todd, G.J. Vermeij, J.B.C. Jackson. 2016c. Formation of the Isthmus of Panama. Science Advances, 2: 8, e1600883. DOI: 10.1126/sciadv.1600883

H. A. Lessios.  2016a. The great Diadema antillarum die-off: 30 years later.  Annual Review of Marine Science 8:267-283 doi:10.1146/annurev-marine-122414-033857

H. A. Lessios, S. Lockhart, R. Collin, G. Sotil, P. Sanchez-Jerez, K. S. Zigler, A. F. Perez, M. J. Garrido, L.B. Geyer, G. Bernardi, V. D. Vacquier, R. Haroun, B.D. Kessing.  2012a. Phylogeography and bindin evolution in Arbacia, a sea urchin genus with an unusual distribution. Molecular Ecology, 21:130-144 DOI:10.1111/j.1365-294X.2011.05303.x

H. A. Lessios. 2011. Speciation genes in free-spawning marine invertebrates. Integrative and Comparative Biology, 51: 456-465

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Harilaos Lessios
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Harilaos A. Lessios

Name

Harilaos

Last name

Lessios

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Staff Scientist
Discipline (Private): 
Developmental Biology
Marine Biology
Molecular Genetics and Genomics
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Staff scientists

Matthew Larsen

English
Hydrology Geology Geography and Biogeography

Inspired experiments and observation by STRI scientists and our many collaborators and students continue to improve our understanding of tropical ecosystems. This information continually changes the way we address environmental stewardship, resource management, and the many challenges ahead.

Matthew Larsen
STRI Coral Reef

Forested Watersheds, Water Resources, and Ecosystem Services, with Examples from the United States, Panama, and Puerto Rico, 2017

Contemporary human uses of tropical forested watersheds and riparian corridors: Ecosystem services and hazard mitigation, with examples from Panama, Puerto Rico, and Venezuela, 2016

As Director Emeritus of the Smithsonian Tropical Research Institute, a unit of the Smithsonian Institution headquartered in Panama City, Panama, I retired in June, 2020 from the job of managing more than 400 employees, an annual budget of $35 million, and the institute’s research facilities throughout Panama. In addition to our resident scientists, our facilities are used annually by more than 1,400 visiting scientists, fellows and interns who come from academic and research institutions in more than 50 nations. STRI furthers the understanding of tropical nature and its importance to human welfare, trains students to conduct research in the tropics, and promotes conservation by increasing public awareness of the beauty and importance of tropical ecosystems.

During my tenure at STRI I increased the diversity of the leadership team, hired 7 new staff scientists, inaugurated new research facilities and supported innovations in communication and public outreach. There is more information about my achievements as Director of STRI here.

Previously, from 2010 to 2014, I was the U.S. Geological Survey Associate Director for Climate and Land Use Change, where I led science programs focused on climate change, land use change, and a national ecological carbon sequestration assessment. Additionally, I managed the Landsat satellite program and the National Climate Change and Wildlife Science Center. Prior to 2010 I served in various scientific leadership roles at the U.S. Geological Survey, following an 18-year research career in that agency. My approximately 90 publications are in marine geology, natural hazards, water resources management, climate change, and ecosystem services.

How do we maximize our contributions as scientists and public servants?

STRI scientists offer unbiased information about tropical environments from rainforests to coral reefs — for the public good. Our science serves all sectors of society in the United States, in Panama where we are based, and throughout the tropics. As a premier tropical research platform, we host long-term, large-scale, studies and we convene scientists from around the world.

As a scientist who dedicated my career to public institutions, I believe that a strong civil service is the backbone of a democratic society. Civil servants are the stewards of information that serves the public good and we guarantee that institutional knowledge and capability are retained during political transition at the top level of national government.

1997 Ph.D., Geography, University of Colorado

1976 BSc., Geology, Antioch College, Yellow Springs, Ohio

Larsen, M.C., 2017, Forested watersheds, water resources, and ecosystem services, with examples from the United States, Panama, and Puerto Rico, In: Ahuja S. (ed.) Chemistry and water: the science behind sustaining the world's most crucial resource, p. 161-182, Elsevier, Amsterdam, ISBN: 978-0-12-809330-6.

Larsen, M.C., 2016, Contemporary human uses of tropical forested watersheds and riparian corridors: Ecosystem services and hazard mitigation, with examples from Panama, Puerto Rico, and Venezuela, Quaternary International, http://dx.doi.org/10.1016/j.quaint.2016.03.016.

Larsen M.C., 2014, Global change and water availability and quality: challenges ahead. In: Ahuja S. (ed.) Comprehensive Water Quality and Purification, vol. 1, p. 11-20. United States of America, Elsevier.

Larsen, M.C., 2012, Global change and water resources, where are we headed? Water Resources Impact, American Water Resources Association, vol. 14, no. 5, p. 3-7.

Larsen, M.C., 2012, Landslides and sediment budgets in four watersheds in eastern Puerto Rico, ch. F in Murphy, S.F., and Stallard, R.F., eds., Water quality and landscape processes of four watersheds in eastern Puerto Rico, U.S. Geological Survey Professional Paper 1789, p. 153-178.

Larsen, M.C., and Webb, R.M.T., 2009, Potential effects of runoff, fluvial sediment and nutrient discharges on the coral reefs of Puerto Rico, Journal of Coastal Research, v. 25, p. 189-208. ISSN 0749-0208.

Keefer, D.K., and Larsen, M.C., 2007, Assessing Landslide Hazards, Science, v. 316, p. 1136-1138.

Larsen, M.C., and Wieczorek, G.F., 2006, Geomorphic effects of large debris flows and flash floods, northern Venezuela, 1999, Tropical Geomorphology with Special Reference to South America, Latrubesse, Edgardo, ed., Zeitschrift für Geomorphologie Suppl. Vol. 145, p. 147-175.

Larsen, M.C. and Santiago-Román, Abigail, 2001, Mass wasting and sediment storage in a small montane watershed: an extreme case of anthropogenic disturbance in the humid tropics, in Dorava, J. M., Palcsak, B.B., Fitzpatrick, F. and Montgomery, D., eds., Geomorphic Processes and Riverine Habitat, American Geophysical Union, Water Science & Application Series Volume 4, p. 119-138.

Larsen, M.C., 2000, Analysis of 20th century rainfall and streamflow to characterize drought and water resources in Puerto Rico, Physical Geography, v. 21, p. 494-521.

Larsen, M.C., Torres-Sánchez, A.J., and Concepción, I.M., 1999, Slopewash, surface runoff, and fine-litter transport in forest and landslide scars in humid-tropical steeplands, Luquillo Experimental Forest, Puerto Rico, Earth Surface Processes and Landforms, v. 24, p. 481-502.

Brown, E. T., Stallard, R. F., Larsen, M. C., Bourlès, D. L., Raisbeck, G. M., and Yiou, F., 1998, Determination of predevelopment denudation rates of an agricultural watershed (Cayaguás River, Puerto Rico) using in situ-produced 10Be in river-borne quartz, Earth and Planetary Sciences Letterss, v. 160, p. 723-728.

Larsen, M.C., and Torres Sánchez, A.J., 1998, The frequency and distribution of recent landslides in three montane tropical regions of Puerto Rico, Geomorphology, v. 24, no. 4, p. 309-331.

Larsen, M.C. and Parks, J.E., 1997, How wide is a road? The association of roads and mass-wasting disturbance in a forested montane environment, Earth Surface Processes and Landforms, v. 22, p. 835-848.

mclarsen.33 [at] gmail.com
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Matthew Larsen
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Scientist Type: 
Emeritus

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Matthew C. Larsen

Name

Matthew

Last name

Larsen

Position

Director Emeritus
Discipline (Private): 
Ecosystem Services
Global Change
External CV: 
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Department: 
Staff scientists
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