Evolution through genetically controlled allometry space.
Understanding evolutionary change requires phenotypic differences between organisms to be placed in a genetic context. However, there are few cases where it has been possible to define an appropriate genotypic space for a range of species. Here we address this problem by defining a genetically controlled space that captures variation in shape and size between closely related species of Antirrhinum. The axes of the space are based on an allometric model of leaves from an F2 of an interspecific cross between Antirrhinum majus and Antirrhinum charidemi. Three principal components were found to capture most of the genetic variation in shape and size, allowing a three-dimensional allometric space to be defined. The contribution of individual genetic loci was determined from QTL analysis, allowing each locus to be represented as a vector in the allometric space. Leaf shapes and sizes of 18 different Antirrhinum taxa, encompassing a broad range of leaf morphologies, could be accurately represented as clouds within the space. Most taxa overlapped with, or were near to, at least one other species in the space, so that together they defined a largely interconnected domain of viable forms. It is likely that the pattern of evolution within this domain reflects a combination of directional selection and evolutionary tradeoffs within a high dimensional space.
Langlade
Nicolas B
NB
Department of Cell and Developmental Biology, John Innes Centre, Colney Lane, Norwich NR4 7UH, United Kingdom.
Feng
Xianzhong
X
Dransfield
Tracy
T
Copsey
Lucy
L
Hanna
Andrew I
AI
Thébaud
Christophe
C
Bangham
Andrew
A
Hudson
Andrew
A
Coen
Enrico
E
D032161:Antirrhinum / Q000033:anatomy & histology* / Q000235:genetics*; D005075:Biological Evolution; D001699:Biometry; D002874:Chromosome Mapping; D005838:Genotype; D006824:Hybridization, Genetic; D008126:Lod Score; D008954:Models, Biological; D010641:Phenotype; D018515:Plant Leaves / Q000033:anatomy & histology*; D025341:Principal Component Analysis; D040641:Quantitative Trait Loci; D013045:Species Specificity