Playing evolution in the laboratory: From the first major evolutionary transition to global warming^(a)

¹ Evolutionary Dynamics Group, Instituto Gulbenkian de Ciência - IGC - Oeiras, Portugal
² cE3c - Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa Lisboa, Portugal
³ Department of Plant Systematics, Ecology and Theoretical Biology, Eötvös Loránd University 1117 Budapest, Hungary
⁴ Evolutionary Systems Research Group, Centre for Ecological Research, Hungarian Academy of Sciences 8237 Tihany, Hungary
⁵ Center for the Conceptual Foundations of Science, Parmenides Foundation - 82049 Pullach/Munich, Germany
⁶ Grup de Genòmica, Bioinformàtica i Biologia Evolutiva (GGBE), Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona - Bellaterra, Barcelona, Spain

^(b) mauro.santos@uab.es

Received: 7 May 2018
Accepted: 29 May 2018

Abstract

Experimental evolution allows testing hypotheses derived from theory or from observed patterns in nature. We have designed a droplet-based microfluidic “evolution machine” to test how transient compartmentalization (“trait-groups”) of independent molecular replicators (likely a critical step in the origin of life) could have prevented the spread of parasitic mutants; that is, inactive RNAs that have been reported to spoil a system of free replicators. In remarkable agreement with the theory, we show that this simple population structure was sufficient to prevent takeover by inactive RNAs. A more complex scenario arises when we use experimental evolution to test field-derived hypotheses; for instance, the idea that temperature is driving genetic spatiotemporal patterns of climate change. In the fly Drosophila subobscura, latitudinal clines in gene arrangement frequencies occur worldwide, and more equatorial gene arrangements are becoming more frequent at higher latitudes as a correlated response to climate change. However, the evolution at different constant temperatures in the laboratory was not consistent with patterns in nature, suggesting some limitations of experimental evolution. Finally, also in D. subobscura, we show that repeatability in experimental evolution is staggeringly consistent for life history traits, making evolution quite predictable and suggesting that laboratory selection can quickly erase differences between populations. Yet, the genetic paths used to attain the same adaptive phenotypes are complex and unpredictable.