Exploring patterns and processes of life on Earth through geobiology and geochemistry
Welcome to the Tejada Lab!
Our laboratory investigates how animal diet and physiology get recorded in organismal tissues and how these biological signatures can be traced through deep time. In parallel, we study how the Amazon rainforest and its extraordinary biodiversity have responded to fluctuating environmental conditions in the recent geological past. These two research programs span very different biological and temporal scales, reflecting our broad interest in understanding life through the integration of biology, paleontology, and geochemistry.
What an animal eats shapes nearly every aspect of its biology: how it grows, behaves, interacts with its environment, and evolves. But how an animal processes food is just as fundamental as what it eats. Digestive and metabolic adaptations allow animals to exploit remarkably different resources, yet the physiological processes that determine how animals digest, assimilate, and metabolically process nutrients (from their transport among tissues to their use within cells) are challenging to infer from the tissues that constitute our chemical and fossil archive. Our lab seeks to recover this hidden dimension of animal biology from the chemical signatures it leaves behind.
Obtaining an isotopic ratio is relatively easy; understanding what that ratio means and which biological processes produced it is the harder, and more interesting, problem. We investigate how physiological and metabolic processes partition isotopes as nutrients move through organisms, and whether those patterns can provide a window into aspects of animal biology that are otherwise difficult to observe. Before using chemical signatures to reconstruct the biology of extinct organisms, however, we need to understand how those signatures arise in living ones. We therefore work across biological scales, from cellular and tissue-level processes to patterns across species and communities, combining experimental approaches with comparative studies of modern and fossil organisms. A major focus of our research is the stable isotope chemistry of individual amino acids, the building blocks of proteins, and what their isotopic variation can reveal about diet, digestive physiology, and metabolism.
At a very different scale, we are interested in the history of the Amazon rainforest, Earth's most biodiverse terrestrial ecosystem. How resilient has this ecosystem been to past climate extremes? How did plant and animal communities respond as environmental conditions changed? And what can those responses tell us about the processes that generate and maintain tropical biodiversity? We investigate these questions through fieldwork in the western Amazon and a multi-proxy approach that integrates stable isotope geochemistry with fossil plant anatomy and taxonomy, palynology, vertebrate paleontology, and sedimentary records. A current focus is reconstructing ecological change during Pleistocene glacial–interglacial cycles, when Amazonian environments experienced climatic conditions substantially different from those of today.
Across both research directions, our approach is driven by the scope of the questions rather than the boundaries of particular disciplines or methods. Whether following an isotopic signal from a cellular process into an animal tissue or reconstructing ecological change across an ancient rainforest, we combine biological, chemical, and paleontological evidence to understand processes that are otherwise difficult to observe, and to extend those insights into the past.
Our lab brings together people with different scientific backgrounds, perspectives, and expertise, reflecting the interdisciplinary nature of the questions we pursue. We aim to provide an environment where young scientists can ask ambitious questions, develop independence, and acquire the skills and confidence to pursue their own paths in science and beyond. We value curiosity, intellectual ambition, hard work, collaboration, and generosity toward others. If you are excited by animals, plants, fossils, chemistry (or by questions that require crossing the boundaries between them) we would be excited to hear from you.