Insights Into Ecology, Evolution and Global Change Responses From Very Long-Term Studies

Abstract

At a time where human activities are altering ecosystems and their associated biodiversity at unprecedented scales (Díaz et al. 2019; McFadden et al. 2023), there is a pressing need to understand how ecosystems function and how they have changed over time, to pinpoint the key processes structuring populations, communities and ecosystems, and to predict how ecosystems and the species inhabiting them will respond to ongoing change. Very long–term studies are crucial because many ecological and evolutionary processes unfold over long time scales, and because the links between cause and effect may take years to manifest (Table 1).

Long-term studies enable not only documentation of changes that may be missed (or misperceived) in shorter term snapshots (Figure 1) but also a better understanding of the importance of year-to-year variability, including rare events, in shaping ecosystem dynamics and evolutionary responses to change (Franklin, Bledsoe, and Callahan 1990). Recent meta-analyses demonstrate the importance of long-term studies to correctly detect the direction of population trends (White 2019; Wright and Calderon 2025) and effects of experimental treatments (Cusser et al. 2021). Further, long-term studies allow for a closer integration between the fields of ecology and evolution (Jarne and Pinay 2023) as longer datasets increasingly capture evolution in action (e.g., Ålund et al. 2024; Johansson et al. 2024), thus enabling investigations of the roles of fundamental evolutionary processes such as phenotypic plasticity and maternal effects in adapting to change (Carroll et al. 2007; Räsänen and Kruuk 2007; Clutton-Brock and Sheldon 2010; Charmantier, Garant, and Kruuk 2014). Critically, such evolutionary responses are likely to differ substantially depending on organisms' pace of life and the environmental conditions encountered over individual lifetimes (Figure 2). Of course, even the longest observational and experimental studies are limited by the time scales of the human research endeavour, which are shorter than those of many ecological and evolutionary processes (Table 1).

By collating a series of papers on very long-term studies in ecology and evolution, this special issue of Ecology Letters highlights the contributions of such studies to advancing our understanding of ecological processes and evolutionary mechanisms. Here, we summarise key findings from the papers in this special issue, grouping them into six areas of research: (1) ecological responses to temporal climate variation and climate change; (2) tipping points and regime shifts; (3) synchrony, stability and stationarity; (4) demographic and environmental determinants of population growth rates; (5) evolutionary patterns and potential and (6) causes and life-long consequences of behaviour. We close with a discussion of their potential to provide structure for inclusive education and professional development, a topic addressed at a greater length by Czapanskiy et al. (2024).

Long-term research programs can provide unique structures for inclusive education and professional development, as discussed by Czapanskiy et al. (2024). Drawing upon 60 years of experience on a long-term study of northern elephant seals (Mirounga angustirostris), they identified four key points that make long-term studies catalysts of inclusive education. (1) Rich data sets enable in-depth analytical and question-oriented training, often with a level of complexity beyond that typically expected from shorter term undergraduate research projects. (2) Well-established and well-equipped research infrastructure provide inclusive entry points into the field of ecology. Both of the above critically allow trainees to build research and self-efficacy skills, while contributing to a long-term research program larger than the individual projects. In addition, long-term studies facilitate professional development through (3) the establishment of networks between individuals at multiple career stages, both locally (within the research program) and globally (through conferences, mentor networks of collaborators), and (4) creating peer cohorts that foster science identity, confidence and self-efficacy while reducing isolation and interpersonal conflicts.

Czapanskiy et al. (2024) argued, however, that the reliance of many long-term research programs on unpaid labour is a critical factor acting against diversity, equity and inclusivity in long-term studies. Their findings from survey responses of 27 researchers who submitted proposals for this Ecology Letters special issue found that whereas long-term studies almost all relied at least in part on undergraduate students for data collection and/or analyses, less than half offered some sort of financial compensation to students (beyond housing and/or transport). Whereas self-funded, volunteer work is common in ecological and evolutionary research, this approach is inequitable in that it discriminates against people who cannot afford to work unpaid for prolonged periods of time, which disproportionately affects members of many historically underrepresented groups (Fournier and Bond 2015). Czapanskiy et al. (2024) suggested that one way to navigate the difficulties of acquiring the necessary recurrent funding to support long-term research work (including by undergraduates and interns) is partnering long-term projects with institutional and/or national diversity, equity and inclusion (DEI) programs, an approach many funding agencies (e.g., NSF, NSERC, ERC) are explicitly encouraging. By investing financially in a culture of inclusion, very long-term studies may well initiate a virtuous cycle whereby young people involved in the program are more likely to pursue and obtain jobs in science in the future (Bailey et al. 2022), and thus be in a position to themselves contribute further to the maintenance of long-term data collection.

Together, the articles presented in this two–part special issue of Ecology Letters clearly show the breadth and depth of contributions, both fundamental and applied, made by very long-term studies. The datasets and code archived together with the articles in these special issues make them even more valuable, enabling others to more easily build on these contributions with further analyses of these data or application of the same analytical methods to other datasets. Indeed, several of these contributions were highly praised by our data editors for their excellent work in presenting code and data in a clear and reproducible way (e.g., Rodrigues et al. 2025). At the same time, issues of fairness of data publication practices to data originators can be particularly fraught for very long-term studies (De Lima et al. 2022). This problem is exacerbated by common citation practices that result in a lack of attribution and citation to data-originating papers (Payne et al. 2012).

Very long-term studies are crucial for quantifying and disentangling effects of climate cycles and global change, understanding ecological and evolutionary processes that unfold over prolonged periods, providing data to inform and evaluate theory and models, and supporting evidence-based management and policy (Lindenmayer et al. 2012). Further, such studies, like long-term field sites, generally become foci for a range of complementary investigations and build communities of researchers, thereby synergistically advancing understanding while providing exceptional learning opportunities (Michener et al. 2009; Muller-Landau and Wright 2024). At a time when the funding culture of scientific research favors short-term projects of 3–5 years at best, it is critical to recognise the outstanding contributions of very long-term studies, and to highlight the importance of continued investment in such research.

Vincent A. Viblanc and Helene C. Muller-Landau co-wrote the paper.

Vincent A. Viblanc co-authored one paper in the associated special issue.