Temperature effects on reproduction of tropical trees: pollen, pollen tubes, and seed production
Tropical forests host incredible biodiversity, and by taking up and storing large quantities of carbon from the atmosphere they play an important role in mitigating anthropogenic climate change. As temperatures are predicted to increase significantly during the current century, it will be important to understand how elevated temperatures will affect basic functions of tropical trees that enable the forests to perform the important biodiversity and carbon cycle services. In the Forest Biology lab we study temperature effects on photosynthesis, respiration, leaf survival, and plant reproduction. In this project, the goal is to establish how temperature affects carbon uptake in photosynthesis.
Linking behavior, genetics, and physiology to discover the basis of sexual diversity in hummingbirds
A species' ability to adapt to a changing environment relies on the diversity within its members. What is the basis of diversity across genetic, phenotypic, and behavioral levels? How is this diversity maintained in populations despite selection? We study the sexual phenotypes of hummingbirds as a pathway to researching these questions.
Comparison of the growth and development of juveniles of the hammerhead shark Sphyrna lewini in the Gulf of Panama and the Gulf of Chiriqui
Scalloped hammerhead sharks (Sphyrna lewini) are important predators in tropical marine ecosystems worldwide but are highly vulnerable to overfishing. In Panama, Sphyrna lewini is the most common shark caught in artisanal fisheries, with a high proportion of the catch being neonates and juveniles. This threat has serious implications for the sustainability of its populations, motivating management efforts. To set effective sustainable harvesting targets, additional information is needed about S. lewini age and growth rates, especially during its early life stages when it is particularly vulnerable to capture by fisheries.
Curation of STRI's legacy archaeology collections
The Smithsonian Tropical Research Institute’s (STRI) Naos Archaeology Lab houses thousands of boxes of archaeological materials (faunal remains, ceramics, lithics, and sediments), as well as archaeological human remains comprising over 600 individuals. As one of the largest and most diverse archaeological collections in Panama, the ongoing analysis of these materials has offered critical learning opportunities for both local and international students and young researchers, and greatly improved knowledge of Panama's prehispanic human populations and their environments. However, as the size of the archaeological collections have expanded over several decades, the need for dedicated collections maintenance and curation has become critical. This project seeks to address this critical need by working to improve both the physical and digital inventory, organization, and preservation of the archaeology collections held at STRI.
Using the fossil record to explore the relationship between reef health and shark communities in the Panamanian Pacific under a changing climate
Climate change poses a serious threat to the persistence of coral reefs and the predators like sharks that call them home. However, the relationship between reef health and shark abundances remain uncertain, and we know little about how it might change under future projected climate change. This is particularly true in marginal reef environments like the Tropical Eastern Pacific, which experience large climate variability due to seasonal upwelling and ENSO (El Niño–Southern Oscillation). Our project leverages a past climatic episode in the Gulf of Panama—an ENSO-driven shutdown of reef accretion and loss of coral habitat—to investigate how reef-associated sharks respond to reef degradation following climate stress.
Paleoecological reconstruction of shark communities in the Panamanian Pacific over millennia using fossil dermal denticles
Reef sharks are essential to ecosystem health. However, they are facing a drastic global decline driven by industrial fishing. Current conservation goals are largely based on studies of shark populations already threatened by human presence, hindering our understanding of shark population decline and the urgency of shark community recovery. The fossil record can provide missing historical context to reconstruct more accurate baselines, understand population changes across time, and aid future management decisions. In Panama, fossil shark scales (dermal denticles) from sediment cores have been used to quantify the relative abundance of sharks before major human impact, particularly in the Caribbean basin. Our project will apply this new paleoecological proxy in the Panamanian Pacific to reconstruct shifts in shark abundance and community structure over the last ~6000 years.
Obligate Mutualism Between Ants and Acacias and the Evolution of New Strategies in Other Organisms
New environments impose selective pressures that can drive the evolution of novel strategies. The obligate association between Pseudomyrmex ants and acacia plants (Vachellia, formerly Acacia) creates a new environment where other organisms adapt to spend either their entire life cycle or a part of it. These organisms tend to be specialized and show a strong preference for living on plants defended by ants compared to other plants. This thesis project theme aims to fill various knowledge gaps regarding the behavior of acacia ants.
Insights into coral reef resilience from analysis of reef benthos photomosaics
The coral reefs of the Eastern Tropical Pacific thrive in a region whose physico-chemical conditions are marginal for the growth of reefs. Despite this, historical data suggest that these reefs have a high capacity to recover after periods of highly stressful environmental conditions, such as those that cause coral bleaching. The Rohr Reef Resilience program (RRR) aims to discover if this previously-observed resilience is a robust characteristic of shallow-water coral reefs in this region, and, if so, to reveal the mechanisms – molecular, physiological, demographic, and ecological -- that underly this resilience. We combine video and photo-mosaic technology, visual surveys, assessments the recovery of reef communities on artificial surfaces, physiological and biochemical analysis to assess corals heath, as well as genomic analyses of coral hosts and the microbes that live in and on them to monitor ecological change along gradients of upwelling intensity and through time.
Navigating Changing Night Skies: How Do Acoustic Specialists Respond to an Increasingly Bright and Noisy World?
Anthropogenic change is dramatically altering Earth’s ecosystems. With the substantial rise in urbanization worldwide, natural habitats are fragmenting and disappearing at a rapid pace. The remaining habitats are exposed to a wide variety of pollutants, including sensory pollutants in the form of increased noise and light levels. These changes can create acoustic and visual environments that differ significantly from those in which local species evolved. In many cases, these environmental and sensory changes disrupt the delicate balance between interacting species. Will animals adapt to these changes through behavioral modifications? Is there a critical threshold beyond which animals can no longer provide key ecosystem services such as seed dispersal and pollination? We address these questions through the study of tropical bats. As highly acoustic animals adapted to foraging in darkness, bats are vulnerable to habitat changes that increase light levels and alter the local soundscape.
Understanding How Mangroves Capture Carbon
Mangroves are highly productive ecosystems that provide critical ecosystem services to coastal communities within the tropics and sub-tropics, including climate change adaptation and mitigation, and food security. Despite the small area they occupy along tropical coastlines, they account for 14% of carbon sequestration in the oceans, and therefore major stores of blue carbon globally. As the world moves towards commoditizing blue carbon, it becomes increasingly important to document the amount of carbon currently held in different biomes AND understand how key rates influence variation in carbon stores in different types of ecosystems and in areas with different environmental conditions. In this project, we are documenting how the current carbon stores, carbon accumulation rate, sediment accretion rates, soil carbon origin, and decomposition rates vary in contrasting mangrove forests in Panama.
Origin and mechanism of transmission of the ciliate that killed millions of sea urchins
The sea urchin Diadema antillarum is a keystone species in coral reefs of the Caribbean because its herbivory limits the growth of algae, which outcompete coral. This sea urchin suffered a mass die-off that eliminated 97% of individuals in 1983-4. In 2022 populations in the West Indies, the Atlantic coast of Mexico and Florida were affected again. The cause of the mortality is the scuticociliate Philaster apodigitiformis. The origin of this pathogenic ciliate is still unknown. The main objective of this project is to determine whether P. apodigitiformis is part of the microbiome of D. antillarum or of other organisms common in the Caribbean that are in contact with the urchin.
Acoustic Monitoring in the San San Pond Sak Wetland: Impact of Boat Noise on Manatees and Analysis of Climatic Variables
The project titled "Acoustic Monitoring in the San San Pond Sak Wetland: Impact of Boat Noise on Manatees and Analysis of Climatic Variables" focuses on using a network of mini underwater hydrophones to complement the existing acoustic monitoring network for manatees, which has been in place since 2015. The goal is to assess the impact of noise on the area's manatee population.
Are insect population dynamics driven by bottom-up resource availability, top-down predation, or direct climate effects in a tropical rainforest?
Concerns about worldwide insect decline are growing, with possible catastrophic consequences for a variety of ecosystem services. Time-series for tropical insects are scarce and limited in temporal range. Since 2009, we have been continuously monitoring with traditional protocols 23 insect taxa at Barro Colorado Island (BCI) in Panama, which is buffered against all insect stressors (habitat loss, pollution, insecticides), but climate change.
Spider Communication in a Variable World
Communication allows animals to manipulate the behaviour of other animals – from coordinating social defenses to deceiving prey. Successful communication usually requires transmission of a signal from a signaling animal, through the environment, to an animal that receives the signal. Therefore, the environment may play a significant role in the success and the evolution of animal communication. This project will use wolf spiders (Lycosidae) – which live and communicate in habitats that can vary over space and time – to understand the various ways that the environment can affect communication.
Understanding the Evolutionary Transition from Omnivore to Plant Specialist through the Internal Anatomy of Ants
Evolutionary transitions often involve morphological and behavioral changes. While external morphological changes associated with the evolution of new traits are well known, changes at the level of internal anatomy remain less studied. Insects' internal organs are fascinating because their exoskeleton can impose constraints on the contents of the head capsule. In this project, we aim to understand the internal structural changes associated with the transition of Pseudomyrmex ants from arboreal, omnivorous habits to an obligatory mutualism with plants.
Quantifying landscape-level variation in tropical forest structure, function, and composition and their change over time
Tropical forests vary widely in their structure, function, and composition, variation that is associated with climate, soils, geomorphology, land use history, and biogeographic realm. Forest structure encompasses the horizontal and vertical distribution of vegetation, which depends on the abundances, spatial arrangement, and morphology of trees and lianas (woody vines) of different forms and sizes. Forest function refers to the ecological roles of forests, including carbon storage, woody productivity, photosynthesis, evapotranspiration, and nutrient cycling, among others. By forest composition, we mean which species with what traits and abundances are present in an area; we focus especially on woody plant functional composition and diversity, as well as woody plant species composition and diversity.
Exploring the potential for automated species identification of tropical plants from hyperspectral and 3D scanning data
Tropical forests account for a majority of terrestrial carbon stocks and biodiversity, and it is thus critical to understand how they are being affected by global climate change. Their high plant diversity offers the potential for high resilience to anthropogenic global change because species vary widely in their responses to environmental variation and the most negatively affected species will invariably become less common. However, this very diversity presents a tremendous challenge to our ability to understand tropical forest function today and to predict how it will respond to global change, as it means interspecific variation is critical. We currently lack the abundant, species-specific data needed to quantify this interspecific variation and capture it in models. Ground-based studies are small-scale and contain inadequate sample sizes of most plant species, and remote sensing data provide large sample sizes but cannot currently distinguish individual species in diverse tropical forests. Technological advances in hyperspectral imaging, laser scanning, and artificial intelligence now offer the potential for automated species identification of individual plants using remote sensing, smartphones, and/or other tools.
Transforming a 100-year old discipline: PollenGeo, a first in digital palynology
Building an extant and fossil Neotropical palynological image training set that will revolutionize the use of pollen data for the Neotropics and ultimately serve as the model for microfossil data analysis globally. The problem to be solved: Palynology is a century-old practice. It is used in a variety of research areas, from pollination ecology to paleovegetation reconstructions and oil exploration. The core of any routine palynological analysis is the task of counting pollen grains. Millions of pollen grains need to be found, identified, counted, and compared to thousands of pollen grains from extant and fossil plants. How do we accomplish this?
Turning up the heat or cooling down: Success of survival of marine invertebrate communities under different temperature scenarios
Understanding the environmental and biological mechanisms shaping communities is a central focus of ecological research. We examine how upwelling activity influences algal and sessile invertebrate growth and top-down control by consumers (fish) in the Tropical Eastern Pacific (TEP). The strength and frequency of upwelling activity varies across the TEP, making it an ideal location to test how temporal and spatial variability in oceanographic conditions influence top-down control of algae and invertebrate communities. The Bay of Panama experiences strong seasonal upwelling, while the Gulf of Chiriqui does not, and environmental conditions remain relatively stable throughout the year. We use this upwelling gradient as a framework to test: (1) does algal/invertebrate settlement and cover increase during upwelling season? (2) how does the species composition of algae and invertebrates change in response to seasonal upwelling events? And (3) does higher algal/invertebrate settlement and growth offset consumer effects?
How trees fight back: community assembly in tropical forests
Why are tropical rainforests so biodiverse? Interactions between trees and other species are key processes that could explain this phenomenon as trees depend on other species for a variety of essential processes, including pollination, seed dispersal, nutrient acquisition, and defense; and are adversely impacted by other species acting as pollen robbers, seed predators, herbivores, and pathogens. Modern molecular tools, such as metabarcoding or qPCR allow for a deeper understanding of these interactions as they allow communities of organisms to be identified from environmental samples. For example, Virola nobilis is a tropical tree that relies on animals such as toucans and monkeys to disperse its seeds. However, seeds are vulnerable to soil organisms, and because microbial communities in the soil under Virola trees can harm Virola seedlings disproportionally compared to other species, their survival is higher when seeds are dispersed several hundred meters. This frees up space for other tree species to grow next to Virola. This project seeks to better understand which organisms control the distribution and abundance of trees and how trees resist the attack of their enemies to become more abundant.
Computer Assisted Taxonomy (CAT) hand in hand with Barcoding: Documenting marine crab diversity in the Panamanian Pacific and Caribbean (Crustacea: Decapoda: Anomura & Brachyura)
Despite the importance of marine crabs (Decapoda: Anomura and Brachyura) from an ecological, biogeographical and evolutionary perspective, studies on their diversity in the Panamanian littoral (Caribbean and Pacific) are scarce, especially those providing reliable identification keys of taxa. This project intends to combine Computer Assisted Taxonomy (CAT) and DNA barcoding to document marine crab diversity in Panamanian waters. Students will be trained in integrative taxonomy (classical, computer-assisted and molecular taxonomy), as well as in fieldwork, laboratory and analytical methods and scientific illustration.
The ecology of Coiba’s rare flora
Coiba Island, one of the largest and most biodiverse islands in the Eastern Pacific and an UNESCO World Heritage Site, has long acted as a “Noah’s Ark” for the mainland’s threatened flora. Its historical isolation—as a penal colony for nearly a century—shielded large areas of its ecosystems from human disturbance, enabling the survival of endemic species and other threatened plant species that have declined elsewhere, some that are at high risk of extinction. Despite its ecological significance, little is known about the status and biology of Coiba’s endemic and endangered plant species. Key knowledge gaps include population sizes, demographic trends, spatial distribution, interactions with pollinators and dispersers, physiological traits affecting vulnerability to climate change, and genetic diversity. This lack of foundational data hampers the development of effective conservation measures. The project aims to address these gaps by conducting a detailed study of the biology and ecology of Coiba’s endemic and threatened plant species.
Comparative genomics of populations and speciation in Neotropical electric fish
A central topic in evolutionary biology is to understand the conditions under which the interplay between natural selection, genetic drift and gene flow can produce new variation. Within this framework, there is a renewed interest in the geographic context of speciation and, in particular, its consequences on genome differentiation and architecture in the generation of new forms. Despite theoretical advancements in this field, there are still few empirical studies exploring how the genome evolves during adaptation and speciation, especially in scenarios of recent colonization. This project aims to bridge that gap through a comparative genomic analysis of three species of neotropical electric fish, utilizing state-of-the-art sequencing technologies such as Oxford Nanopore and Illumina, along with advanced bioinformatics tools.
STRI-Max Planck Collaboration: Characterization of Environmental Variation Generated by Upwelling Events Along the Tropical Eastern Pacific
Coastal oceanographic conditions along Central America's Pacific coast are highly variable across time and space. Surface water accumulation transported by the Equatorial Countercurrent creates warm, oligotrophic conditions throughout the region. However, this warm environment changes dramatically during the boreal winter, when strong northeast winds blow through topographic depressions along the Central American cordillera. Wind action in the Gulf of Panama, Papagayo, and Tehuantepec generates seasonal upwelling events, causing surface water cooling and increased nutrient availability. As winds decrease during spring and early summer, coastal conditions return to a warm, oligotrophic state (D'Croz and O'Dea 2007, O'Dea et al. 2012). These dynamic coastal conditions, which characterize Central America's Pacific coast, provide an ideal setting to study how regional and temporal variation in environmental conditions and primary productivity influence ecological processes that determine community structure in tropical marine ecosystems. Monitoring coastal environmental conditions along regional upwelling gradients is a fundamental aspect of this research.
