My research spans two main areas: (1) revealing drivers of biodiversity dynamics and stability via data synthesis and quantitative methods such as empirical dynamic modeling, and (2) developing and applying environmental DNA and RNA for biodiversity conservation.
Biodiversity dynamics under global change
The majority of ecological theory is grounded in assumptions of stable equilibria, but a rich body of evidence demonstrates that irregular fluctuations of natural populations can be caused by nonlinear dynamics such as oscillations and chaos. Yet, the influence of environmental and biological drivers as well as global change on nonlinear dynamics remains unclear. We analyzed ~500 global marine fish time series using empirical dynamic modeling and show that temperature variation amplifies the degree of nonlinearity in juveniles and adults, while life history mediates nonlinearity for the latter, dampening it in slow-lived species (Hechler and Krkosek, 2025). Our results challenge assumptions of stable dynamics and suggests nonlinear fluctuations of fish populations are magnified by size-selective fisheries and increasing environmental variability from global climate change.
Because nonlinear dynamics are ubiquitous in nature and are shaped by the environment, I’m investigating how they influence ecosystem stability and functioning through several ongoing projects. Check back for results, soon!
Relevant publications:
Hechler, R.M., & Krkosek, M. 2025. Temperature variation and life history mediate the degree of nonlinearity in fluctuations of global marine fish populations. In revisions. (bioRxiv preprint link)
Hechler, R.M. 2025. Quantifying species interactions in the Anthropocene. Nature Reviews Biodiversity, 1(2), 89.
My research develops environmental (e)DNA and (e)RNA methods that go beyond species detection and applies them for biodiversity conservation and ecological inference. We provided some of the first empirical evidence demonstrating that, contrary to long-held assumptions, eRNA can persist long enough to be recovered and extracted (Kagzi, Hechler et al. 2022). We then showed that eRNA can reveal the physiological stress response of Daphnia exposed to an experimental heat wave (Hechler et al. 2023). Furthermore, we highlighted the potential of eRNA for characterizing population demographics, such as the proportion of different life stages (Hechler and Cristescu 2024). Most recently, I highlighted the integration of eDNA with empirical dynamic modeling to infer causal species interactions and quantify their strengths, which I believe could be broadly applied given the growing use of eDNA in global biodiversity monitoring initiatives (Hechler 2025). We have detailed these methods in a forthcoming book chapter to make them widely accessible (McGarvey, Hechler, et al., in press).
I currently have ongoing projects applying these methods for wild Pacific salmon conservation, in collaboration with the Musgamagw Dzawada’enuxw Fisheries Group and Salmon Coast Field Station. More to come shortly!
Relevant publications:
Hechler, R.M. 2025. Quantifying species interactions in the Anthropocene. Nature Reviews Biodiversity, 1, 89. [link]
Hechler, R.M., & Cristescu, M.E. (2024). Revealing population demographics with environmental RNA. Molecular Ecology Resources, 24(4), e13951. [link]
Hechler, R.M., Yates, M.C., Chain, F.J.J., & Cristescu, M.E. (2023). Environmental transcriptomics under heat stress: Can environmental RNA reveal changes in gene expression of aquatic organisms? Molecular Ecology, 34(13), e17152. [link, From The Cover]
Kagzi, K., Hechler, R.M., Fussmann, G.F., & Cristescu, M.E. (2022). Environmental RNA degrades more rapidly than environmental DNA across a broad range of pH conditions. Molecular Ecology Resources, 22(7), 2640-2650. [link]
McGarvey, D. J., Hechler, R. M., Troutman, A., & Falke, J. A. (In press). Fish assemblages. In Methods in stream ecology (4th ed.). Academic Press. F. R. Hauer, G. A. Lamberti, J. L. Tank, & R. Hall (Eds.)
