Molecular Evolution of Ecological Specialisation: Genomic Insights from the Diversification of Murine Rodents

Penulis: Emily Roycroft, Colin M. Callahan , Jacob A. Esselstyn, Jeffrey M. Good, Adnan Moussalli, and Kevin C. Rowe
Adaptive radiations are characterized by the diversification and ecological differentiation of species, and replicated cases of this process provide natural experiments for understanding the repeatability and pace of molecular evolution. During adaptive radiation, genes related to ecological specialization may be subject to recurrent positive directional selection. However, it is not clear to what extentpatternsoflineage-specificecologicalspecialization(includingphenotypicconvergence)arecorrelatedwithsharedsignatures of molecular evolution. To test this, we sequenced whole exomes from a phylogenetically dispersed sample of 38 murine rodent species, a group characterized by multiple, nested adaptive radiations comprising extensive ecological and phenotypic diversity. We found that genes associated with immunity, reproduction, diet, digestion, and taste have been subject to pervasive positive selection during the diversification of murine rodents. We also found a significant correlation between genome-wide positive selection and dietary specialization, with a higher proportion of positively selected codon sites in derived dietary forms (i.e., carnivores and herbivores) than in ancestral forms (i.e., omnivores). Despite striking convergent evolution of skull morphology and dentition in two distantly related worm-eating specialists, we did not detect more genes with shared signatures of positive or relaxed selection than in a nonconvergent species comparison. Although a small number of the genes we detected can be incidentally linked to craniofacial morphology or diet, protein-coding regions are unlikely to be the primary genetic basis of this complex convergent phenotype.Ourresultssuggestalinkbetweenpositiveselectionandderivedecologicalphenotypes,andhighlightspecificgenesand general functional categories that may have played an integral role in the extensive and rapid diversification of murine rodents. Key words: adaptive radiation, comparative genomics, convergent evolution, exome capture, Murinae, positive selection.

Genome Biology Evolution 13(7): 1 - 16

DOI: doi:10.1093/gbe/evab103

No. Arsip : LIPI-20220211