Scientific activities take place within the structured sets of ideas and assumptions that define a field and its practices. The conceptual framework of evolutionary biology emerged with the Modern Synthesis in the early twentieth century and has since expanded into a highly successful research program to explore the processes of diversification and adaptation. Nonetheless, the ability of that framework satisfactorily to accommodate the rapid advances in developmental biology, genomics and ecology has been questioned. We review some of these arguments, focusing on literatures (evo-devo, developmental plasticity, inclusive inheritance and niche construction) whose implications for evolution can be interpreted in two ways—one that preserves the internal structure of contemporary evolutionary theory and one that points towards an alternative conceptual framework. The latter, which we label the 'extended evolutionary synthesis' (EES), retains the fundaments of evolutionary theory, but differs in its emphasis on the role of constructive processes in development and evolution, and reciprocal portrayals of causation. In the EES, developmental processes, operating through developmental bias, inclusive inheritance and niche construction, share responsibility for the direction and rate of evolution, the origin of character variation and organism-environment complementarity. We spell out the structure, core assumptions and novel predictions of the EES, and show how it can be deployed to stimulate and advance research in those fields that study or use evolutionary biology.

https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.2015.1019

The extended evolutionary synthesis: its structure, assumptions and predictions.

Fifty years ago, Ernst Mayr published a hugely influential paper on the nature of causation in biology, in which he distinguished between proximate and ultimate causes. Mayr equated proximate causation with immediate factors (for example, physiology) and ultimate causation with evolutionary explanations (for example, natural selection). He argued that proximate and ultimate causes addressed different questions and were not alternatives. Mayr's account of causation remains widely accepted today, with both positive and negative ramifications. Several current debates in biology (for example, over evolution and development, niche construction, cooperation, and the evolution of language) are linked by a common axis of acceptance/rejection of Mayr's model of causation. We argue that Mayr's formulation has acted to stabilize the dominant evolutionary paradigm against change but may now hamper progress in the biological sciences.

https://science.sciencemag.org/content/sci/334/6062/1512.full.pdf

Cause and Effect in Biology Revisited: Is Mayr's Proximate-Ultimate Dichotomy Still Useful?

Many biologists are asking whether environmentally initiated phenotypic change (i.e., ‘phenotypic plasticity’) precedes, and even facilitates, evolutionary adaptation. However, this ‘plasticity-first’ hypothesis remains controversial, primarily because comprehensive tests from natural populations are generally lacking. We briefly describe the plasticity-first hypothesis and present much-needed key criteria to allow tests in diverse, natural systems. Furthermore, we offer a framework for how these criteria can be evaluated and discuss examples where the plasticity-first hypothesis has been investigated in natural populations. Our goal is to provide a means by which the role of plasticity in adaptive evolution can be assessed.

/pdf/evaluating-plasticity-first-evolution-in-nature-key-criteria-4l3m0r0y9h.pdf

Evaluating 'Plasticity-First' Evolution in Nature: Key Criteria and Empirical Approaches

Between-individual differences in behavioural plasticity within populations: causes and consequences

This year is the 50th anniversary of Tinbergen’s (1963) article ‘On aims and methods of ethology’, where he first outlined the four ‘major problems of biology’. The classification of the four problems, or questions, is one of Tinbergen’s most enduring legacies, and it remains as valuable today as 50 years ago in highlighting the value of a comprehensive, multifaceted understanding of a characteristic, with answers to each question providing complementary insights. Nonetheless, much has changed in the intervening years, and new data call for a more nuanced application of Tinbergen’s framework. The anniversary would seem a suitable opportunity to reflect on the four questions and evaluate the scientific work that they encourage. Origins of Tinbergen’s questions

/pdf/tinbergen-s-four-questions-an-appreciation-and-an-update-mpz09kc9vk.pdf

Tinbergen's four questions: an appreciation and an update

￻￻ ￻ Explaining the origins of novel traits is central to evolutionary biology. Longstanding theory suggests that developmental plasticity, the abilityof an individual to modify its development in response to environmental conditions, might facilitate the evolution of novel traits. Yet whether and how such developmental flexibility promotes innovations that persist over evolutionary time remains unclear. Here, we examine three distinct ways by which developmental plasticity can promote evolutionary innovation. First, we show how the process of genetic accommodation provides a feasible and possibly common avenue by which environmentally induced phenotypes can become subject to heritable modification. Second, we posit that the developmental underpinnings of plasticity increase the degrees of freedom by which environmental and genetic factors influence ontogeny, thereby diversifying targets for evolutionary processes to act on and increasing opportunities for the construction of novel, functional and potentially adaptive phenotypes. Finally, we examine the developmental genetic architectures of environment-dependent trait expression, and highlight their specific implications for the evolutionary origin of novel traits. We critically review the empirical evidence supporting each of these processes, and propose future experiments and tests that would further illuminate the interplay between environmental factors, condition-dependent development, and the initiation and elaboration of novel phenotypes.

/pdf/the-role-of-developmental-plasticity-in-evolutionary-2dlryvrf96.pdf

H. Fred Nijhout

Papers

The role of developmental plasticity in evolutionary innovation

22 – Origin of Butterfly Wing Patterns