Populations under microevolutionary scrutiny: what will we gain?

Abstract

Understanding the evolution of biodiversity and the function of biological systems are burning and linked questions in biology. Evolution of biodiversity begins at the level of microevolution, with the differentiation of individuals in populations. The study of this process splits into two conceptually different approaches (1) the concept of functional biology of testing hypothesis by precisely controlled and forward-directed experiments (digital and experimental evolution), and (2) the concept of a theory-based historical narrative (testing hypothesis on events in the past for their suitability to best explain the present). Here, I discuss and emphasize the benefits of the study of natural bacterial populations for a deeper understanding of prokaryotic biology. Also, I adress current problems in taxonomy at the 'species' level which obviously need discussion and clarification. I exemplify this with a natural model population for such studies, Bacillus simplex from "Evolution Canyon", Israel.

The temperature-adaptive fatty acid content in Bacillus simplex strains from ‘Evolution Canyon’, Israel

“…However, genetic data as such, even if available at the extent of full genome sequences, would not necessarily indicate the type and direction of phenotypic changes on which selection operates (Mayr, 1959(Mayr, , 1997(Mayr, , 2004. This study, together with earlier ones (Sikorski & Nevo, 2005, therefore strengthens the necessity for populationbiology-based phenotypic analyses, together with genetic and ecological studies, when approaching the microevolution of bacteria (Sikorski, 2008). By demonstrating here a second phenotype correlating with the habitat-dependent distribution of genotypic groups, FA content, this study additionally supports the notion of bacterial species as being represented by ecotypes (Cohan & Perry, 2007;Koeppel et al, 2008;Sikorski, 2008).…”

“…A study on microevolution in prokaryotes should therefore not just limit itself to mostly DNA-sequence-based studies, in order to identify habitat-associated genetic groups, but should also attempt to understand the emergence of such genetic groups due to potential ecological influences, i.e. to identify phenotypes that would correlate with the environment (Sikorski & Nevo, 2007;Sikorski, 2008).…”

Identifying the fundamental units of bacterial diversity: A paradigm shift to incorporate ecology into bacterial systematics

“…We recommend that they be recognized also as the fundamental units of diversity in bacterial systematics (32). We suggest that, when multiple ecotypes are discovered within the accepted phylogenetic range of an established species (e.g., with 1% divergence in 16S rRNA), the ecotypes should be recognized and named by adding an ''ecovar'' epithet to the species binomial, for example, by naming the ecotypes within B. simplex.…”

Fine-scale evolution: genomic, phenotypic and ecological differentiation in two coexisting Salinibacter ruber strains

“…Although comparisons of genomes of different species give insights on a larger scale of evolution, the so-called microevolution (Abby and Daubin, 2007) can only be addressed by comparing genomes of different strains within the same species. Microevolution studies can reveal how bacterial genomes evolve, provide insights in the hidden diversity within a species' population and elucidate the ecological mechanisms that drive microbial radiation (Sikorski, 2008). Current knowledge on microevolution stems mostly from studying strains of pathogenic bacteria but is unmatched for environmentally relevant prokaryotes.…”