Research

Although I have worked on numerous topics, I feel that my work most often revolves around the following themes. 

Metacommunities: The concept of the metacommunity – a set of local communities connected by the dispersal of species in a landscape – has transformed my research since the early 2000s (Leibold et al. 2004, Leibold and Chase 2018, Leibold et al. 2022). This is because it combines (almost) all of the basic processes that determine community dynamics, including environmental effects, species interactions, dispersal, and stochasticity (the only processes that are not well incorporated are evolutionary dynamics that occur within species such as population differentiation and speciation). Since it’s general inception (Leibold et al. 2004, but see earlier work such as Levins and Culver 1969, Horn and MacArthur 1975), this concept has developed into one of the most active areas of community ecology. For me, it has shown that almost all the concept that were previously developed about local ecological dynamics have taken on a very different significance (see Leibold and Chase 2018) and I think this concept has been, and will continue to be, fundamental in the development of the field.

My more recent work on metacommunities focuses on how we can model and infer metacommunity processes from basic data on distributions, environmental variables, and landscape distributions in naturally diverse metacommunities. A promising approach is to use “joint species distribution models” (JSDMs) because these identify patterns that related such data to each other in a comprehensive manner (Ovaskainen et al. 2017). While these models provide tremendous insights into metacommunities, there remain important biases in using them to infer the parameters driving these patterns (Blanchet et al. 2020, Poggiato et al. 2021). Nevertheless, they remain the most informative and sophisticated tools at hand and there are likely going to be improvements in the near future. A particularly useful component is that they can dissect the contributions of each species and/or each site to the overall metacommunity-level pattern (Leibold et al. 2022). 

Related advances that use temporal dynamics may provide more explicit parameter estimation from data and, together with colleagues, we have recently developed such methods based on the principle of “Maximum Caliber” (Jackson et al. 2026).

Food web assembly dynamics along environmental gradients: Ecology has long struggled to balance its understanding of competition among species at one trophic level (oftentimes focused on resource competition) that we can call “horizontal” dynamics, with its understanding of interactions among trophic levels, “vertical” dynamics. Although more difficult to study and understand, it is the joint dynamics  of horizontal and vertical interactions that are actually at play in nature. This point can be traced back at least to Charles Elton in his book on Animal Ecology in the form of the food web concept. One aspect of this interaction is how things change along environmental gradients that either influence the bottom-most resources of the food web (i.e. “bottom-up”) vs organisms that are higher-up in the web (i.e. “top-down”). The early work of my career was focused on this using simplistic food web models (Leibold 1989, 1996) and studying them in experimental and correlational analyses (e.g. Leibold 1991, Leibold and Wilbur 1992, Leibold et al. 1997) and I continue to be interested in this area (e.g. Leibold et al. 2017). Incorporating these ideas with metacommunity ecology remains however challenging even if it is fascinating.

Evolution in Metacommunities: As mentioned above, the most important missing piece of “metacommunity ecology” as commonly conceived, is the role of evolution, including both microevolution (within species changes in time or space) and macroevolution (primarily speciation). With colleagues, especially Luc De Meester, Mark Urban, and Nicolas Loeuille), I’ve been involved in trying to identify how this may modify our understanding of metacommunities. Most of the work I’ve been involved with looks at how local adaptation to local environmental differences can alter patterns of coexistence, diversity, and the distribution of species in a metacommunity landscape (Loeuille and Leibold 2008a, 2008b, 2014, Leibold et al. 2019, 2022) but also phylogeny (Leibold et al. 2010). I’m still fascinated by this question even though my current work has not focused on it.

The Niche Concept: “Niche theory” and its application somehow seem to lay at the core of ecology since “Ecology” can broadly be defined as the study of the relationships between organisms and their environment (including other organisms) and the “Niche” can be defined as the actual relationship between organisms and their abiotic environment (the Hutchinsonian Niche) and other species (the MacArthur-Levins Niche). However the earlier theoretical work somehow floundered when applied to experimental and distributional data, leading to a disuse of the term in the 1980s and 90s. In an attempt to go back to basics, and inspired by a study resource competition by MacArthur (1974), and its successful extension by D. Tilman (1982), I proposed that a more mechanistic interpretation of the concept could by had by dissecting the “relationship” idea into mathematically convenient “response” and “impact” components (Leibold 1995). Together is Jon Chase, we expanded this idea to define what is often called “Contemporary Niche Theory” (Chase and Leibold 2009). This remains the core approach that I use in thinking about metacommunities.