Lead : Cédric Gaucherel and Sébastien Barot
It is not common to question the laws of ecology; Yet this is exactly what this working theme is proposing within the GDR. What do we mean by that? A detour through neighbouring disciplines can enlighten us. With at least four centuries of hindsight, physics has a long tradition of perfecting laws, making it possible to explain in a reliable and universal way (by definition, proven and without exception) its phenomena (Barberousse et al. 2000, Hartmann and Frigg 2005). This is not the case with ecology and evolutionary sciences, and even with proven principles (by definition, which are not questioned) of theories (sets of principles) such as natural selection or Mendelian laws are still much debated (Mayr 2004, Morange 2017). Of course, models regularly challenge accepted principles and test their associated hypotheses (Israel 1996, Hartmann and Frigg 2005).
Biology is readily quite reductionist, ecology, more holistic, sometimes seeks universal laws (Hubbell 2001, Brown et al. 2002, Gaucherel 2013) and continually questions the reliability of the principles that it brings to light, even on the universality of the theories which could result from it. Whether or not it is believed that there are laws in ecology or not, several interesting corollary questions emerge from this question. For example, one is entitled to ask whether a law should relate to mechanisms (processes) or reasons (patterns)? Because while physical laws are generally based on mechanisms, some of them (e.g. gravitation) often resemble patterns and retain a phenomenological flavour (e.g. fractals and allometries). Some even question what the mechanisms are and what any causal explanation is worth (Israel 1996, Barberousse et al. 2000). And when ecology highlights allometric laws, it is part of this same tradition (Brown et al. 2002, Hatton et al. 2015). In addition, some laws are purely statistical (e.g. law of large numbers), far from any mechanism (Frank 2009).
And if ecologists highlighted a law in their field, would it have ecological specificities? In particular, biology and ecology all know the importance of scales and levels of organization in living things. Would an ecological law be affiliated with a particular level of organisation? Certain laws well known to ecologists attempt to explain the distribution of species, either by chance (Hubbell 2001) or by other observed regularities (Neill and Gignoux 2008, Tilman 2011). Several of them link several ecological compartments or several levels of organisation between them (Hardin 1960, MacArthur and Wilson 1963, Tilman 2011). Can these principles be considered as laws? We can guess that the status of such laws will not be similar to that of physical laws which appear, in the eyes of biologists, much more robust and universal (Putnam 1975, Gaucherel 2013). What exceptions, what variations, in these ecological laws, are we ready to accept? And further, how to manage the contradictions or the possible interactions between ecological laws?
Ecology does not have to follow the path of physics or chemistry, but it is entitled to be inspired by them. It can also be inspired by all related disciplines, from physics (Brown et al. 2002, Neill and Gignoux 2008), to economics, including linguistics (Gaucherel 2019). Several recent attempts go in this direction, and a field of research illustrates this growing interest in laws in ecology. Indeed, it would be daring to claim that ecological objects and phenomena violate physical laws, such as thermodynamics, or biological laws, such as natural selection (Harte 2002). Beyond the laws themselves, it is the history of neighbouring disciplines, particularly biology, that can prove to be a source of innovation in ecology (Morange 2017). The old debates on evolution, a field which made a noticeable irruption in ecology, show that it is interesting to seek laws where, previously, one still had only a list of processes and a classification. objects.
Still, the more pragmatic would question: What would be the use of such laws? Would they be there for the sole intellectual pleasure of theorists? Or would they have a real daily utility for managers, farmers or geneticists? Would such laws help to make predictions? Many think so, and claim that a better knowledge of the mechanisms and principles associated with central objects, such as the ecosystem or the population (Hardin 1960, Tilman 2011), would undoubtedly provide assistance to those who have to manage these objects on a daily basis. still poorly understood (Gaucherel 2019). Even if it turned out that ecology does not have laws, reflecting on this question would contribute as much to basic ecology as it does to applied ecology.
As part of this transversal axis we will interact with philosophers of science and we want to design a first list of general laws by doing an online survey.
Complementarity with the GDR Statistical Ecology
The GDR Statistical Ecology aims to develop and disseminate statistical methodologies adapted to the various fields of ecology, including in particular the algorithmic aspects of the fit to data (maximum likelihood, Markov Chain Monte Carlo), data management (data citizen, …) and conceptual of applied statistics (e.g, frequentist vs Bayesian philosophy). The GDR Theory and Modeling of Biodiversity addresses questions upstream and downstream of the use of these methodologies: which data to seize for which questions? Which statistical models also make theoretical sense / how to theoretically interpret their parameters? Are there classical empirical analyses that the theory can prove are uninterpretable? How to reduce the complexity of theoretical models to fit them to necessarily limited data? Are there ecological questions of importance to the theory that currently escape empirical analysis?