TY - JOUR T1 - Key Issues Review: Evolution on rugged adaptive landscapes JF - bioRxiv DO - 10.1101/112177 SP - 112177 AU - Uri Obolski AU - Yoav Ram AU - Lilach Hadany Y1 - 2017/01/01 UR - http://biorxiv.org/content/early/2017/03/03/112177.abstract N2 - Adaptive landscapes represent a mapping between genotype and fitness. Rugged adaptive landscapes contain two or more adaptive peaks: allele combinations that differ in two or more genes and confer higher fitness than intermediate combinations. How would a population evolve on such rugged landscapes? Evolutionary biologists have struggled with this question since it was first introduced in the 1930’s by Sewall Wright.Discoveries in the fields of genetics and biochemistry inspired various mathematical models of adaptive landscapes. The development of landscape models led to numerous theoretical studies analyzing evolution on rugged landscapes under different biological conditions. The large body of theoretical work suggests that adaptive landscapes are major determinants of the progress and outcome of evolutionary processes.Recent technological advances in molecular biology and microbiology allow experimenters to measure adaptive values of large sets of allele combinations and construct empirical adaptive landscapes for the first time. Such empirical landscapes have already been generated in bacteria, yeast, viruses, and fungi, and are contributing to new insights about evolution on adaptive landscapes.In this Key Issues Review we will: (i) introduce the concept of adaptive landscapes; (ii) review the major theoretical studies of evolution on rugged landscapes; (iii) review some of the recently obtained empirical adaptive landscapes; (iv) discuss recent mathematical and statistical analyses motivated by empirical adaptive landscapes, as well as provide the reader with source code and instructions to implement simulations of adaptive landscapes; and (v) discuss possible future directions for this exciting field.GenomeThe heritable genetic information of an individual organism.GeneA sequence of nucleotides in the genome, the basic functional unit determining hereditary traits.LocusThe location of a gene on the genome.AlleleVariant of a specific gene; multiple alleles of the same gene can differ in sequence and function.GenotypeA specific allele combination.PhenotypeThe physical manifestation of a genotype, including the sum of the organisms’ traits such as metabolism, behavior, morphology, etc.EvolutionThe change in frequencies of different alleles and allele combinations in populations over time.Natural selectionThe sum of the processes that drive changes in frequencies of heritable traits due to the differences in reproductive success these traits induce; for example, differences in growth rates, survival, or fecundity.Random genetic driftThe sum of the processes that drive changes in frequencies of heritable traits due to random effects, disregarding natural selection; for example, sampling error in small populations.RecombinationThe process in which alleles from two genotypes combine to produce new allele combinations.FitnessThe contribution of specific genotypes to the next generations, usually given by the reproductive success of individuals carrying these genotypes, which integrates factors such as survival, fecundity, etc.MutationThe process in which alleles randomly change to other alleles.EpistasisInteractions between different loci such that the phenotype or fitness effect of an allele changing depends on the identities of alleles in other loci.Sign epistasisInteractions between loci that change an allele’s contribution to fitness from deleterious to beneficial and vice versa.Fixation probabilityThe probability that an allele will take over a population. Usually refers to a rare allele, integrating the deterministic effect of natural selection with the stochastic effect of random genetic drift. ER -