Genetic architecture underlying the parallel evolution of leaf ecomorphs in Viburnum

• Published in: Evolutionary journal of the Linnean Society 2024-01, Vol.3 (1)
• Main Authors: Moeglein, Morgan K, Eaton, Deren A R, Maya-Lastra, Carlos A, Sweeney, Patrick W, Dion, Kirstin, Olson, Mark E, Cacho, N Ivalu, Donoghue, Michael J, Edwards, Erika J
• Format: Article
• Language: English
• ISSN: 2752-938X; 2752-938X
• DOI: 10.1093/evolinnean/kzae036

Abstract In a neotropical lineage of the plant clade Viburnum (Adoxaceae) several leaf ecomorphs evolved independently and repeatedly as the group radiated through cloud forests of North and South America. Here, we focus on one pair of co-occurring sister species within this radiation with strongly contrasting leaf morphotypes and document the presence of phenotypically diverse and genetically admixed hybrid individuals in multiple hybrid swarms. Hybrid phenotypes are generally intermediate in form, but sometimes show parental or entirely novel and transgressive combinations of leaf traits, suggesting that parental leaf ecomorphs can be functionally and genetically dissociated. We used admixture mapping within hybrid swarms to investigate the genetic architecture of key traits comprising these leaf ecomorphs and uncovered loci proximal to known genes implicated in leaf development, including some that may alter multiple leaf traits simultaneously, potentially facilitating the emergence of leaf syndromes. We conclude that the shared genetic architecture underlying some traits, such as leaf size and marginal teeth, could promote the repeated evolution of these traits in concert, while low levels of genetic linkage between other leaf traits supports the hypothesis that selection promoted the repeated assembly of particular combinations of leaf traits as Viburnum radiated throughout the neotropics.