Some species flourish when many do not: a pattern in data on ecological communities

Patterns in species × sample tables of communities depend above all on the organisms of the data sets and the conditions involved. Patterns that surpass individual sets are of special interest. Our question, looking for a shared pattern in 12 sets, is if relative abundances among species are independent of the sample, or formulated alternatively, if species have abundances that are correlated with total abundances over samples. For exploration we study the overdispersion/aggregation of the data. A relatively high variation in the total abundances of samples is noticed, indicating an effect of environmental variation. Overdispersion imposes constraints on the accommodation of relatively high abundance values to samples with a relatively low total abundance. The null hypothesis of ‘no association’ is modelled by permutation/resampling of the data at the level of the individual. A correlation study of actual and permuted sets is performed. All actual sets contain a significant number of species that defy our question. These species flourish when many do not. The relation of our question with issues in theoretical ecology, such as the assumption of a neutral effect of environmental conditions and/or of neutral characteristics of species, is discussed.

The publications of Ramon Margalef in Investigación Pesquera and Scientia Marina: The beginnings of marine ecology in the CSIC

Ramon Margalef López (1919-2004) was one of the most prominent scientists of the 20th century in the fields of limnology, oceanography and ecology. His contributions to theoretical ecology, which won him international recognition, were based on a great deal of laboratory and field work and on extensive observations of the natural world, a passion that he acquired at a young age. Some of the early papers of Ramon Margalef appeared in the Publicaciones del Instituto de Biología Aplicada, but as of 1955 many of his marine studies were published in Investigación Pesquera, the journal of the Instituto de Investigaciones Pesqueras of the CSIC in Barcelona. He also wrote several articles for Scientia Marina, the journal that replaced Investigación Pesquera in 1989 after the Instituto de Investigaciones Pesqueras became the Institut de Ciències del Mar. The present article aims to give an overview of Margalef’s contributions to these journals to mark the celebration in 2019 of the 100th anniversary of his birth.

Sustainability Problematization and Modeling Opportunities

A sound theoretical ground is required for sustainability related concepts reconciliation and operationalization. The current study investigates the opportunities to conceive a homogenous sustainability model derived from theoretical ecology, using as a prototype the “organization” concept from the Chemical Organizations Theory (COT). A sustainability problematization and a literature examination try to capture and link some useful perspectives and sustainability connected concepts. Some of the most influential methods and tools are reviewed, in particular among those relating to the triple bottom line framework and to the ecological footprint family, together with concepts close to the core sustainability definition, like resilience and circularity. Theoretical ecology provides candidate goal functions based on self-organization gradients, such as fitness functions and thermodynamic orientors. The COT formalism provides a higher abstraction level and the algorithms for patterns identification in a reactions network. The sustainability problematization reveals the motifs of a possible model of “total ecosystem”, which subordinates the anthropic cultural (social–economic) system to the thermodynamic, chemical, biological, and cultural determinisms regulating biological and cultural species of an ecological network.

Testing and Refining State-and Prediction-Based Theory

This chapter highlights the importance of testing and refining the behavior theory in individual-based models (IBMs). Establishing a model's credibility is not the only reason to test theory for behavior. Doing so also offers a new and productive approach to theoretical ecology: a way to develop a toolbox of across-level theory useful for modeling populations of adaptive individuals. One can refer to testing and refining behavior sub-models as theory development, and one can do it by following the classic inductive reasoning cycle of posing, testing, and falsifying alternative hypotheses. The chapter provides a brief introduction to the pattern-oriented theory development process and presents several examples.

Theoretical Ecology

This book continues the authoritative and established edited series of theoretical ecology books initiated by Robert May which helped pave the way for ecology to become a more robust theoretical science, encouraging the modern biologist to better understand the mathematics behind their theories. This latest instalment in the Theoretical Ecology series builds on the legacy of its predecessors with a completely new set of contributions. Rather than placing emphasis on the historical ideas in theoretical ecology, the editors have encouraged each contribution to: i) synthesize historical theoretical ideas within modern frameworks that have emerged in the last ten to twenty years (e.g., bridging population interactions to whole food webs); ii) describe novel theory that has emerged in the last twenty years from historical empirical areas (e.g., macro-ecology); and iii) cover the booming area of theoretical ecological applications (e.g., disease theory and global change theory). The result is a forward-looking synthesis that will help guide the field through a further decade of development and discovery.

Introduction

This book continues the authoritative and established edited series of theoretical ecology books initiated by Robert May which helped pave the way for ecology to become a more robust theoretical science, encouraging the modern biologist to better understand the mathematics behind their theories. This latest instalment in the Theoretical Ecology series builds on the legacy of its predecessors with a completely new set of contributions. Rather than placing emphasis on historical ideas in theoretical ecology, the editors have encouraged each contribution to: i) synthesize historical theoretical ideas within modern frameworks that have emerged in the last ten to twenty years (e.g., bridging population interactions to whole food webs); ii) describe novel theory that has emerged in the last twenty years from historical empirical areas (e.g., macro-ecology); and iii) cover the booming area of theoretical ecological applications (e.g., disease theory and global change theory). The result is a forward-looking synthesis that will help guide the field through a further decade of development and discovery. Early chapters are collectively more about the building blocks for understanding dynamics of interacting species in time and space, including coexistence, consumer-resource and biological lags, stochasticity, and stage structure. Later, chapters are representative of the study of networks, a large growth area. These include matrix theory, mutualistic networks, community structure, body size and system structure, and network ecology. Novel concepts such as trait-based models and meta-population ecology are then presented. Applied theoretical ecology is then covered by chapters on disease ecology, climate change dynamics, and stable states.

A structural theory of mutualistic networks

Mutualistic interactions among free-living species have shaped much of biodiversity on Earth. Ironically, however, mutualism has not been prominently featured in theoretical ecology. Recent efforts have tried to fill this gap by assessing to what degree the structure of plant-animal mutualistic networks affects species persistence. Here, we review this growing literature emphasizing how different papers relate to each other and to what extent their conclusions depend on particular assumptions. A central concept in this effort is that of structural stability. While main approaches in theoretical ecology focus on local dynamical stability, structural stability shifts the question to how large is the range of parameter values compatible with the stable coexistence of all species. This structural approach has shown that mutualism has to be understood as a balance to competition and that network architecture should be seen as affected by both stability and feasibility constraints. Constraints on the dynamical stability of these communities set up a maximum mutualistic strength. Constraints on their feasibility tend to push interaction strength near this limit and select for a nested architecture. These results, however, assume similar interspecific competition amongst species and very small mutualistic strength. Future work should thus explore the consequences of relaxing these constraints.

Areas of current and future growth

This chapter will reflect on the chapters in this book and suggest directions and gaps that theory will have to consider as we move forward. Our goal here is to motivate future work in light of the developments discussed in this book. We will emphasize the role of the empirical-theoretical connection that will be a thread across chapters. Clearly, eco-evolutionary theoretical developments are currently being developed, and we imagine and hope that future versions of theoretical ecology will reveal strong growth in this important area. Much work is being developed related to evolutionary response to global change (e.g., evolutionary rescue). Again, consistent with the themes being developed in this book, we would argue that this multi-disciplinarian approach to theory (evolution and ecology, agriculture and ecology, economics and ecology, society and ecology) have become part of the toolbox of modern ecology and modern theoretical ecology and likely will play a massive role in future theoretical development.