title: Evolution of allometry in antirrhinum.
abstract: Correlated variation in shape and size (allometry) is a major component of natural diversity. We examined the evolutionary and genetic basis for allometry using leaves and flower petals of snapdragon species (Antirrhinum). A computational method was developed to capture shape and size variation in both types of organ within the Antirrhinum species group. The results show that the major component of variation between species involves positively correlated changes in leaf and petal size. The correlation was maintained in an F2 population derived from crossing two species with organs of different sizes, suggesting that developmental constraints were involved. Identification of the underlying genes as quantitative trait loci revealed that the larger species carried alleles that increased organ size at all loci. Although this was initially taken as evidence that directional selection has driven diversity in both leaf and petal size, simulations revealed that evolution without consistent directional selection, an undirected walk, could also account for the parental distribution of organ size alleles.
authors.affiliation: Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JH, United Kingdom.
authors.forename: Xianzhong
authors.initials: X
authors.lastname: Feng
authors.forename: Yvette
authors.initials: Y
authors.lastname: Wilson
authors.forename: Jennifer
authors.initials: J
authors.lastname: Bowers
authors.forename: Richard
authors.initials: R
authors.lastname: Kennaway
authors.forename: Andrew
authors.initials: A
authors.lastname: Bangham
authors.forename: Andrew
authors.initials: A
authors.lastname: Hannah
authors.forename: Enrico
authors.initials: E
authors.lastname: Coen
authors.forename: Andrew
authors.initials: A
authors.lastname: Hudson
mesh_terms: D032161:Antirrhinum / Q000033:anatomy & histology / Q000145:classification / Q000235:genetics*; D005075:Biological Evolution; D035264:Flowers / Q000033:anatomy & histology / Q000235:genetics; D018515:Plant Leaves / Q000033:anatomy & histology / Q000235:genetics