Biology

Dr. Belden is an environmental toxicologist with over 25 years of experience in measuring and assessing the toxicity of environmental contaminants. He also enjoys teaching and has taught courses ranging from Introductory Biology to Ecotoxicology. Dr. Belden currently serves as Department Head for the Department of Integrative Biology.

Research Interests:

My research group focuses on environmental toxicology and ecotoxicology. Current projects include:
1) The presence of carcinogens in playground soil

2) Availability and risk posed by pesticide seed treatments
3) Developing passive samplers to measure harmful algal toxins
4) Improved measurement of micro and nano plastics in tissue

5) Bioavailability of organic contaminants in systems containing microplastics 

My research integrates field ecology, developmental biology, and comparative genomics to understand how diverse animal life histories emerge and evolve. Using reptiles and fishes as study systems, I focus on two interrelated axes of variation: (1) the mechanisms of sex determination, which link developmental environments to reproductive outcomes, and (2) the environmental and genomic drivers of aging, which shape variation in survival and longevity. Ultimately, my work seeks to uncover the mechanistic underpinnings of organismal fitness to improve predictions regarding species resilience in the face of environmental change.

I am broadly interested in promoting critical thinking through scientific inquiry and hands-on research. As Faculty Fellow for Instructional Excellence, I am focused on helping faculty and students better teach and better learn. In my plant biology research, I am interested in how plants perceive and respond to environmental stimuli, and in how humans have interacted with plants through the domestication process.

Research Interests:

Plant responses to abiotic stress
Plant domestication
Plant development

My primary duties are to teach general education courses and oversee the labs for Plant Biology (PBIO 1404). These labs have a semester-long, course-based undergraduate research experience (CURE). My research centers around teaching and learning, and on US agricultural exports.

Research Interests:

Much of my research has dealt with finding new experiments that can be conducted in CURE labs. Future work will include teaching others how to implement a CURE at their institutions.

Inspired by Alfred Lotka's work a century ago, and reinvogorated by bioinorganic chemistry and ecological stoichiometry in the post-genomic era, we frame biological systems as dynamical compositional systems governed by the relative proportions of chemical elements. Rather than beginning with organisms, traits, or genes, this perspective starts with elemental building blocks and treats biosystems, from cells to ecosystems, as material systems embedded within geochemical contexts. A central premise is that biological function and productivity are constrained not only by individual elements but by their joint, compositional dynamics, requiring equal attention to numerator and denominator chemistry.

By explicitly treating elemental data as compositional, atom-first biology connects mechanistic, element-specific knowledge to emergent biological and ecological outcomes across scales. This approach enables integration of inorganic chemistry, biophysics, physiology, and ecology within a unified quantitative framework, allowing predictions about growth, tolerance, productivity, and system-level responses to environmental change that are difficult to obtain using single-element or trait-centric approaches.

Atom-first biology does not propose a new discipline, but rather re-centers biology on well-established principles from inorganic chemistry and non-equilibrium biophysical systems that have historically remained siloed from mainstream biological inference. The framework is particularly relevant for interdisciplinary teams working at the interface of ecology, environmental chemistry, physiology, toxicology, statistics, and applied mathematics, where compositional constraints and scale-invariant material principles shape both data structure and biological outcomes.

Research in my lab uses macroecological and phylogenetic approaches to address questions that lie at the interface of ecology and evolutionary biology. Our primary focus is on large-scale infectious disease dynamics and patterns of biodiversity. The tools we use are large datasets, machine learning, and other computational methods.  

Research Interests:

MACROECOLOGY OF INFECTIOUS DISEASES
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A current major focus of research in my lab is large-scale patterns of disease biodiversity, an area in which many basic questions of wide interest remain to be answered. For example, whether parasites follow the same macroecological rules that tend to apply to free living species is largely unknown (see this paper for an overview). One of my recent projects is on the effects of phylogeny, range overlap, and ecological similarity on patterns of parasite sharing among wild ungulate species. This study also considered for the first time the effects of sampling bias on apparent patterns of parasite overlap among hosts (i.e., are pairs of well-studied hosts more likely to have known shared parasites than poorly studied hosts), and the degree to which trophic links promote the spread of parasites among distantly related species (in this case for ungulate parasites to be shared with carnivore hosts). Another recent project investigated methods for extrapolating large scale (e.g., global) patterns of parasite biodiversity from the sparse data on parasite distributions that are currently available, and much of my current work applies a macroecological perspective to more applied questions such as elucidating the ecological and anthropogenic factors that promote the spillover of zoonotic disease from wildlife to humans.

​Much of my work to until recently was associated with a NSF (in collaboration with NIH and USDA) funded research coordination network focused on the macroecology of infectious disease I lead, which you can read about here. I am currently leading a multi-year project (funded by NIH) to study the factors that promote the spillover of Ebolavirus and other filoviruses from wild mammal hosts to humans in Africa, a collaborative project between researchers at OSU and the Center for the Ecology of Infectious Diseases at UGA. We are investigating the role of ecological factors such as climate and host richness, as well as anthropogenic a socioeconomic factors such as human encroachment into wild areas and poverty.

I am also leading a new NSF funded project to look at how socioeconomic factors such as poverty, availability of doctors and vaccine hesitanceny have affected realized case numbers of COVID-19 across Oklahoma counties.  This work is in collaboratioon with many OSU faculty including Merle Eisenberg (History), Tao Hu (Geography), Juwon Hwang (Media and Strategic Communications), Rebecca Kaplan (History), Patrick and Lucas Stolerman (Mathematics). Outside of OSU, Mekala Sundaram, a machine-learning expert and former OSU post-doctoral scholar who recently took a faculty position at the University of Georgia, is also part of the team.  The work began in January 2024 and will be going through 2027.

BIODIVERSITY
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In addition to research on infectious diseases, I have also engaged in collaborative research on global patterns of biodiversity in mammals. Using resources such as published species level mammal supertrees, IUCN data on mammal geographic ranges, and compiled data on mammalian behavioral, morphological, and ecological data in PanTHERIA and other sources it is now possible to address key questions in evolutionary ecology at unprecedented scales. For example, topics that I am currently engaged in include the effects of niche conservatism on the phylogenetic heritability of geographic range distributions in mammals, the factors that affect patterns of parasite community similarity between mammal species, and how trait diversity relates to other dimensions of biodiversity such as species richness and phylogenetic diversity.

In the future, using techniques and theoretical approaches developed in mammals, I will broaden this research to encompass other vertebrate groups, particularly amphibian and reptile groups. Supertrees are available or soon will be available for most major vertebrate groups, and species geographic range data are available for the majority of terrestrial vertebrates. Squamate reptiles are one group that is particularly ripe for this approach.  Squamates consist of more than 10,000 recognized species, constituting more than a quarter of all terrestrial vertebrate biodiversity.  Yet compared to birds, mammals and amphibians we know relatively little about them.  For example, nearly 40% of species have not yet had their risk of extinction evaluated by the IUCN, and the first global biodiversity map to include all squamate species was only published in 2018.  Our knowledge of the factors that drive large scale patterns of squamate biodiversity and variation in the threat status of species remains in its relative infancy compared to other terrestrial vertebrates, and I have several ongoing projects focused on squamate reptile biodiversity and macroecology.

Ongoing work in this area is being funded by a grant from the US-Isreal Binational Science Foundation.  The goal of the project is to explore global dimesions of biodiversity in tetrapods (mammals, birds, reptiles and amphibians).  My collaborators on the project include faculy in Isreal, Canada, Arizona State University and the University of Georgia.   The latest project is to understand how variation in species richness (the number of species in an ecological community) is related to variation in trait diversity across terrestrial assemblages of squamate reptiles (lizards and snakes).  This study includes trait data for more than 10,000 species of squamates, and considers variation among the species found in every 100x100 km grid cell on earth.

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EVOLUTIONARY ECOLOGY OF AMPHIBIANS AND REPTILES
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Much of my research before coming to Oklahoma State University focused on the evolutionary ecology of amphibians and reptiles, particularly turtles in the family Emydidae. Emydidae includes many well known North American Turtle species, such as the Eastern Box Turtle (Terrapene carolina), the Painted Turtle (Chrysemys picta), and the Pond Slider (Trachemys scripta). It has been an ideal study system for me because the family is geographically very widespread and species in it are ecologically incredibly diverse. It is one of the very few families of vertebrates to include aquatic, terrestrial, and semi-terrestrial species as well as herbivorous, carnivorous, and omnivorous species. It is also among the few terrestrial clades to exhibit a "reverse latitudinal diversity gradient," where more species occur in temperate than tropical regions. Some species in the genus Graptemys also exhibit some of the most extreme sexual size dimorphisms known in tetrapods, with adult females that are more than twice as long as adult males and roughly an order of magnitude more massive.

Topics I have addressed in emydids include the origins of large scale patterns of species richness, the evolution of ecological specialization, the origins of large scale patterns of community structure, and the evolution of sexual size dimorphisms. One theme that runs through much of this work is that niche conservatism and dispersal limitation greatly influence emydid biodiversity at large spatial scales. Other projects in herpetology include the origins of large scale patterns of species richness in hylid frogs, the evolution of endosulfin resistance in North American frogs and the evolution of phenotypic plasticity in more than two dozen species of North American ranid, bufonid, and hylid frogs and parallel patterns of adaptive evolution the turtle families Emydidae and Geoemydidae.

More information:

Lab members. 

Opportunties to join my lab.