Evolution of allometry in antirrhinum.
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.
Feng
Xianzhong
X
Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JH, United Kingdom.
Wilson
Yvette
Y
Bowers
Jennifer
J
Kennaway
Richard
R
Bangham
Andrew
A
Hannah
Andrew
A
Coen
Enrico
E
Hudson
Andrew
A
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