TY - JOUR T1 - A single nucleotide change underlies the genetic assimilation of a plastic trait JF - bioRxiv DO - 10.1101/2020.06.29.176990 SP - 2020.06.29.176990 AU - Paul Vigne AU - Clotilde Gimond AU - Céline Ferrari AU - Anne Vielle AU - Johan Hallin AU - Ania Pino-Querido AU - Sonia El Mouridi AU - Christian Frøkjær-Jensen AU - Thomas Boulin AU - Henrique Teotónio AU - Christian Braendle Y1 - 2020/01/01 UR - http://biorxiv.org/content/early/2020/06/29/2020.06.29.176990.abstract N2 - Genetic assimilation – the evolutionary process by which an ancestral environmentally sensitive phenotype is made constitutive – is a fundamental concept in biology. Its evolutionary relevance is debated, and our understanding of its prevalence, and underlying genetics and molecular mechanisms, is poor. Matricidal hatching is an extreme form of maternal provisioning induced by adverse conditions, which varies among Caenorhabditis elegans populations. We identified wild isolates, sampled from natural populations across multiple years and locations, that express a derived state of near-constitutive matricidal hatching. A single amino acid change in kcnl-1, encoding a small-conductance calcium-activated potassium channel subunit, explains most of this variation. A gain-of-function mutation altering the S6 transmembrane domain causes inappropriate activation of the K+ channel, leading to reduced vulval muscle excitability, and thus reduced expulsion of embryos, irrespective of environment. Using reciprocal allelic replacements, we show that this amino acid change is sufficient to induce constitutive matricidal hatching whilst re-establishing the ancestral protein abolishes matricidal hatching and restores egg-laying, thereby doubling lifetime reproductive fitness under benign conditions. While highly deleterious in the laboratory, experimental evolution showed that KNCL-1(V530L) is maintained under fluctuating resource availability. Selection on a single point mutation can therefore underlie the genetic assimilation of an ancestrally plastic trait with drastic life-history consequences.Competing Interest StatementThe authors have declared no competing interest. ER -