Taxon-Level Stasis and Epigenetics: A Challenge to Neo-Darwinism
Neo-Darwinism, the modern synthesis of Darwinian evolution with genetics, posits that gradual accumulation of genetic mutations , filtered by natural selection , drives the formation of new species and higher taxa. However, the phenomenon of taxon-level stasis, where groups of organisms exhibit minimal morphological change over vast geological timescales, challenges this gradualist perspective. Furthermore, recent advances in epigenetics, the study of heritable changes in gene expression that do not involve alterations to the underlying DNA sequence, add another layer of complexity to this challenge. Taxon-Level Stasis: A Brief Overview Taxon-level stasis is evident in the fossil record, where many lineages appear abruptly and persist for millions of years with little directional change. This pattern contradicts the neo-Darwinian expectation of gradual and continuous morphological transformation. Examples of stasis are abundant, including " living fossils " l...