The QTN Program and the Alleles That Matter for Evolution: All That’s Gold Does Not Glitter

By M. Rockman. Evolution; international journal of organic evolution, 2011

675 citations recorded by the source corpus.

The search for the alleles that matter, the quantitative trait nucleotides (QTNs) that underlie heritable variation within populations and divergence among them, is a popular pursuit. But what is the question to which QTNs are the answer? Although their pursuit is often invoked as a means of addressing the molecular basis of phenotypic evolution or of estimating the roles of evolutionary forces, the QTNs that are accessible to experimentalists, QTNs of relatively large effect, may be uninformative about these issues if large‐effect variants are unrepresentative of the alleles that matter. Although 20th century evolutionary biology generally viewed large‐effect variants as atypical, the field has recently undergone a quiet realignment toward a view of readily discoverable large‐effect alleles as the primary molecular substrates for evolution. I argue that neither theory nor data justify this realignment. Models and experimental findings covering broad swaths of evolutionary phenomena suggest that evolution often acts via large numbers of small‐effect polygenes, individually undetectable. Moreover, these small‐effect variants are different in kind, at the molecular level, from the large‐effect alleles accessible to experimentalists. Although discoverable QTNs address some fundamental evolutionary questions, they are essentially misleading about many others.

Subfields: Genetics

View Paper: https://www.semanticscholar.org/paper/f8e97e8c4ab34a20b2635f4a58a46e0172dc8817

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In Genetics

Citations in the corpus

Finding the Genomic Basis of Local Adaptation: Pitfalls, Practical Solutions, and Future Directions (2016, neutral): “It has been argued that most heritable variation for phenotypes is due to small-effect loci (e.g., Rockman 2012) and that the polygenic architectures that underlie quantitative traits (continuously varying phenotypes) are probably elusive to most genome scans (Barton and Keightley 2002; Stephan…”
Patterns of phenotypic plasticity and local adaptation in the wide elevation range of the alpine plant Arabis alpina (2018, background): “Even in the case where the same trait evolved in different areas, most evolutionary relevant traits have most likely a highly polygenic structure (Rockman, 2012): this means that the same trait can evolve through the effect of many different genes (convergent phenotypic evolution with divergent…”
Mechanisms of Thermal Tolerance in Reef-Building Corals across a Fine-Grained Environmental Mosaic: Lessons from Ofu, American Samoa (2018, background): “…in corals; however; it is important to note that studies on model systems with large sample sizes often exceeding a thousand individuals still struggle to identify genes of significant impact for certain phenotypes, representing a cautionary tale for this pursuit in corals (Rockman, 2012).”
Evolution of Ecological Niche Breadth (2017, background): “Understanding the genetic basis for phenotypic variation is necessary to accurately assign costs and constraints to niche breadth evolution (Rockman 2012).”
Genotype-by-Environment Interaction and Plasticity: Exploring Genomic Responses of Plants to the Abiotic Environment (2013, neutral): “Broadly interpreting QTL studies is fraught with challenges (Rockman 2012).”