Losing Complexity: The Role of Simplification in Macroevolution

Macroevolutionary patterns can be produced by combinations of diverse and even oppositional dynamics. A growing body of data indicates that secondary simplifications of molecular and cellular structures are common. Some major diversifications in eukaryotes have occurred because of loss and minimalisation; numerous episodes in prokaryote evolution have likewise been driven by the reduction of structure. After examining a range of examples of secondary simplification and its consequences across the tree of life, we address how macroevolutionary explanations might incorporate simplification as well as complexification, and adaptive as well as nonadaptive dynamics.M.A.O.’s research and the ISHPSSB symposium on which this paper is based were funded by a University of Sydney Bridging Support Grant and a University of Bordeaux IdEx Chair of Excellence. J.G.W. is supported by European Molecular Biology Organization ALTF 761-2014, and EMBOCOFUND2012, GA-2012-600394. I.R.T.’s research is supported by ERC-2012-Co-616960, BFU2014-57779-P, and Project 2014 SGR 619.Peer reviewe

Concepts of the last eukaryotic common ancestor

Insight into the last eukaryotic common ancestor (LECA) is central to any phylogeny-based reconstruction of early eukaryotic evolution. Increasing amounts of data enable such reconstructions, without necessarily providing further insight into what LECA actually was. We consider four possible concepts of LECA: an abstract phylogenetic state, a single cell, a population, and a consortium of organisms. We argue that the view most realistically underlying work in the field is that of LECA as a population. Drawing on recent findings of genomically heterogeneous populations in eukaryotes (‘pangenomes’), we examine the evolutionary implications of a pangenomic LECA population. For instance, how does this concept affect standard expectations about the ecology, geography, fitness, and diversification of LECA? Does it affect evolutionary interpretations of LECA’s cellular functions? Finally, we examine whether this novel pangenomic concept of LECA has implications for phylogenetic reconstructions of early eukaryote evolution. Our aim is to add to the conceptual toolkit for developing theories of LECA and interpreting genomic datasets.M.A.O.’s research is supported by the French government via the ‘Investments for the future’ Programme, IdEx Bordeaux (ANR-10-IDEX-03-02). M.M.L. is supported by a Marie Skłodowska-Curie Individual Fellowship under the EU Framework Programme for Research and Innovation Horizon 2020 (Project ID 747789). J.G.W. was supported by a College for Life Sciences Fellowship at the Wissenschaftskolleg zu Berlin. I.R.-T. was supported by a European Research Council Consolidator Grant (ERC-2012-Co -616960) grant and funding (BFU2017-90114-P) from Ministerio de Economía y Competitividad (MINECO), Agencia Estatal de Investigación (AEI), and Fondo Europeo de Desarrollo Regional (FEDER)

Leading Up in the Scholarship of Teaching and Learning

Scholarship of teaching and learning (SoTL) scholars, including those who are not in formal positions of leadership, are uniquely positioned to engage in leadership activities that can grow the field, influence their colleagues, and effect change in their local contexts as well as in institutional, disciplinary, and the broader Canadian contexts. Drawing upon the existing SoTL literature and our own diverse experiences, we propose a framework that describes institutional contexts in terms of local SoTL activity (microcultures) and administrative support (macro-level) and use it to describe the many ways that SoTL scholars can and do “lead up” to effect change depending on their own context. We conclude by inviting scholars to consider, reflect upon, and experiment with their leadership activities, not only for their own professional growth but also to contribute to the literature in this area. Les professeurs qui font des recherches dans le domaine de l’avancement des connaissances en enseignement et en apprentissage (ACEA), y compris ceux qui n’occupent pas un poste de leadership formel, occupent une position unique pour s’engager dans des activités de leadership qui peuvent faire avancer le domaine, influencer leurs collègues et effectuer des changements dans leurs contextes locaux ainsi que dans les contextes plus vastes de leur établissement, de leur discipline et du contexte canadien en général. En nous appuyant sur la documentation déjà publiée en ACEA et sur nos diverses expériences personnelles, nous proposons un cadre qui décrit les contextes institutionnels en termes d’activités d’ACEA locales (micro-cultures) et de soutien administratif (niveau macro) que nous utilisons pour décrire les diverses manières dont les chercheurs en ACEA peuvent en arriver à effectuer des changements selon leur propre contexte. En conclusion, nous invitons les chercheurs à prendre en considération leurs activités de leadership, à y réfléchir et à faire des expériences, non seulement pour leur propre croissance professionnelle mais également pour contribuer à la documentation dans ce domaine