The article by Dolph Schluter discusses the mechanisms of speciation driven by natural selection, focusing on two broad categories: ecological speciation and mutation-order speciation. Ecological speciation occurs when divergent natural selection acts on different environments, leading to reproductive isolation. Mutation-order speciation involves the fixation of different mutations in separate populations adapting to similar selection pressures, resulting in reproductive isolation. The author highlights that ecological speciation is more commonly observed and supported by evidence, while mutation-order speciation is less well-documented but has been documented in instances of intragenomic conflict. The article also reviews the historical development of the concept of speciation, from Darwin's initial ideas to modern definitions based on reproductive isolation. It emphasizes the importance of understanding the genetic basis of reproductive isolation and the role of natural selection in driving speciation. The article concludes by discussing the challenges and progress in identifying the genes and mechanisms underlying speciation, particularly in the context of ecological and mutation-order processes.The article by Dolph Schluter discusses the mechanisms of speciation driven by natural selection, focusing on two broad categories: ecological speciation and mutation-order speciation. Ecological speciation occurs when divergent natural selection acts on different environments, leading to reproductive isolation. Mutation-order speciation involves the fixation of different mutations in separate populations adapting to similar selection pressures, resulting in reproductive isolation. The author highlights that ecological speciation is more commonly observed and supported by evidence, while mutation-order speciation is less well-documented but has been documented in instances of intragenomic conflict. The article also reviews the historical development of the concept of speciation, from Darwin's initial ideas to modern definitions based on reproductive isolation. It emphasizes the importance of understanding the genetic basis of reproductive isolation and the role of natural selection in driving speciation. The article concludes by discussing the challenges and progress in identifying the genes and mechanisms underlying speciation, particularly in the context of ecological and mutation-order processes.