How did the discovery of genes affect the study of animal evolution?

The discovery of genes fundamentally transformed the study of animal evolution by providing a concrete, mechanistic basis for the heritable variation required by natural selection.3

Initially, the rediscovery of Mendelian inheritance in 1900 led to a period of conflict between "mutationists," who believed evolution occurred through sudden, large-scale genetic changes, and "biometricians," who supported Darwinian gradualism. This tension was resolved in the 1920s and 1930s through the development of population genetics, which demonstrated that continuous variation could be explained by Mendelian laws.123

This integration culminated in the "synthetic theory of evolution," which combined Darwinian selection with genetics. Key impacts include:1

• Understanding Variation: Mutation was identified as the primary source of genetic variation, providing the raw material for natural selection.4
• Defining the Unit of Evolution: The species was redefined as a gene pool, with speciation viewed as the process of gene pool fragmentation and divergence.3
• Molecular Phylogeny: Modern researchers use the molecular structure of genes and DNA sequences to measure evolutionary divergence, often surpassing traditional anatomical methods in accuracy.5
• Evo-Devo: The field of evolutionary developmental biology (evo-devo) now studies how genetic mechanisms shape the diversity of organic forms.67