Meta-analysis and big data analysis to synthesize ecological and biological themes

We aim to examine the universality of biological principles across diverse species (ranging from bacteria to large mammals) and ecological generalizations through the collection and meta-analysis of existing literature datasets. Our research focuses on key relationships such as metabolic rates relative to body size, net growth efficiency of elements, and ecological stoichiometry across taxa. For ecological propositions, we have developed datasets on topics like food chain length and radiocesium metabolism to investigate the generality of food web structures.

Climate change biology

Although rapid climate changes, such as global warming, are anticipated, their impacts on ecosystems remain insufficiently understood. To address this, we study the response of plant and animal phenology to climate change across Japan using long-term datasets, including phenological observations from the Japan Meteorological Agency. From a macroecological perspective, we have elucidated relationships between latitude and climate change responses, as well as regional variations in genetic diversity and climate adaptability. Furthermore, we explore the effects of phenological mismatches on interacting systems, such as the timing of flowering and pollinator emergence or host-parasite population dynamics.

Environmental DNA

In aquatic environments like lakes and rivers, environmental DNA (eDNA) — derived from animal feces, skin cells, and other biological materials — exists within the water. eDNA analysis allows us to detect species-specific DNA using techniques such as quantitative PCR (real-time PCR, digital PCR) and high-throughput sequencing to estimate the presence, absence, or biomass of organisms. These methods offer the potential to evaluate biodiversity in a water body by simply sampling the water. Our ongoing research focuses on refining and applying these cutting-edge eDNA techniques.

Food Webs

Food webs, which illustrate predator-prey interactions, are foundational for understanding ecosystem structure and function. These interactions influence community dynamics, ecosystem processes, and services. One crucial food web attribute, food chain length (the number of trophic levels from producers to top predators), has been a topic of extensive research and debate. We conduct field studies to test hypotheses related to food chain length using stable isotope analysis. Additionally, our research investigates the temporal and spatial structures of food webs, nutrient cycling, and material flow in diverse aquatic ecosystems — including lakes, rivers, tidal flats, and coastal regions — to deepen our understanding of food web dynamics.