Maurel Marie-Christine - Biodiversity and Evolution

Philippe Grandcolas

Marie-Christine Maurel

Series Editor

Marie-Christine Maurel

First published 2018 in Great Britain and the United States by ISTE Press Ltd and Elsevier Ltd

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ISBN 978-1-78548-277-9

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Philippe Grandcolas

The word biodiversity is fashionable. This term, which is a contraction of biological diversity, was penned by Thomas Lovejoy, Walter G. Rosen and Edward Osborne Wilson to refer to the living world without any restriction of aspect or study level . In the dramatic context of the sixth extinction, the word was so popularized by countless publications that it became well known to all. In only a few decades, the word biodiversity then replaced another one the living world to identify this essential element of our environment. It focuses on the differences between individuals (variety) rather than their main common points (living world laws). After our altogether recent discovery of biological laws (for example, heredity), we have learned since to study their consequences in our environment as a whole, no longer focusing on our laboratory organisms.

Even so and in terms of semantics, the word biodiversity does not integrate all aspects of the living world. One of the main characteristics of biodiversity is that it is alive and, as such, it permanently changes. The variations between individuals in populations and species result from their differentiation during biological evolution. To understand and interpret it, we must reconstruct the paths followed by evolution, by tracking them among kinship relationships (phylogenies) that can be inferred between individuals. To understand a trajectory, must we not draw a line between a point of origin and stages?

Furthermore, although most people understand that the present variety is the result of past evolution, few of us take into account that the organisms we see are constantly changing. In fact, at our timescale, many species seem the same in the main lines of their phenotypes; however, individuals are in fact subject to selection pressure variations, gene transfers, random mutations, development mechanics and, finally, interactions with the environment, including the biological environment. In short, no species is unchanging and we realize it when we delve into the details of their genome or their anatomy at the level of a few generations. By releasing or exercising a selection pressure, we will see a previously stable state, which we thought was fixed, gradually changing.

Biological evolution, which we think results from a long process marked by a series of deceiving ancestral figures, is in fact a permanent phenomenon, characterized by the constant reproduction and transmission of modified ancestral traits to descendant. The best proof of evolution in the eyes of the common people should reside in the composite likeness of their children (how many creationists are thus proud of their offspring, without suspecting their apostasy!). The inheritable appearance of resistances over a few generations in bacteria or insects, in other words metabolic or physiologic changes enabling them to deal with antagonist substances (antibiotics, insecticides, etc.), is another striking example.

Consequently, our view of biodiversity must take into account this past and future. Nothing in biology makes sense except in the light of evolution, to quote Theodosius Dobzhansky , and nothing in the future of biodiversity makes sense if we do not understand that it constantly changes and adjusts in a subtle and often little predictable way.

This book focuses on illustrating this duality of the living world, which reproduces and transmits its ancestral traits to descendant, but changes despite everything. In addition to improvement of our knowledge, studying biodiversity and evolution is a valuable school of ethics. Faced with other organisms, we put into perspective our human states and behaviors. We face evolutionary change, and we learn that things are not immutable. Finally, we face the consequences of our action on the environment and maybe we learn something from all these retroactive effects that affect us directly.