Ecological and evolutionary implications of genomic structural variations

Large genomic segments spanning millions of nucleotides commonly differ between any two genomes, including between monozygotic twins (Bruder et al., 2008). These structural variations (SVs) include deletions, insertions, duplications, inversions, and translocations. SVs have been associated with human genetic diseases (Weischenfeldt et al., 2013), but can also facilitate adaptation (Iskow et al., 2012) and speciation (Noor et al., 2001; Rieseberg, 2001). In this research topic, the contributed articles offer insights into the ecological and evolutionary implications of genomic SVs, emphasizing the advances, limitations, and importance of studying the evolution of structural polymorphisms in model and non-model organisms. The recent developments in genomic technologies and methodologies allow the study of SVs in basically any organism, including ecological models with limited prior genetic information available. In this research topic, Fan and Meyer (Fan and Meyer, 2014) provide an extensive catalog of various types of genomic variation across four recently diverged cichlid lineages and speculate on the relevance of SVs for one of the largest adaptive radiations in vertebrates. The phylogenetic context of their study suggests that point mutations are commonly obtained at the basal nodes, whereas the rates for acquiring SVs are increased at the tips of their phylogeny. This study provides a starting point to examine the role of SVs in the diversification and speciation of cichlids. Inversions are SVs that may be particularly effective in promoting speciation due to a subsequent reduction in recombination when heterozygous (Butlin, 2005). Feder et al. (Feder et al. 2014) summarize previous theoretical efforts evaluating the impact of inversions on speciation, and assess the consequences of inversions in the divergence of two populations through simulations. The authors examine how the genomes of these populations become distinct through recombination barriers. Results from their simulations suggest that conditions most favorable to incite speciation involve inversions that are already fixed between populations before secondary contact. Segregating inversions occur in a variety of systems (Faria and Navarro, 2010) including the mosquito Anopheles. Ayala et al. (Ayala et al., 2014) review the relationship between inversions and adaptive traits in Anopheles. Several inversions across eight species have been linked to phenotypic traits including insecticide resistance, higher tolerance to xeric environments, and mate choice. The authors urge that further