Population structure, demographic history, and evolutionary patterns of a green-fruited tomato, Solanum peruvianum (Solanaceae), revealed by spatial genetics analyses.
OBJECTIVE
Wild relatives of crop species have long been viewed as an important genetic resource for crop improvement, but basic information about the population biology of these species is often lacking. This study investigated the population structure, demographic history, and evolutionary patterns of a green-fruited relative of the cultivated tomato, Solanum peruvianum.


METHODS
We investigated spatial genetics of S. peruvianum and screened for loci potentially under natural selection by integrating amplified fragment length polymorphism (AFLP) genotypes, phenotypic data, geography, and geographic information system (GIS)-derived climate data of 19 natural populations.


RESULTS
Solanum peruvianum had a moderate degree of population differentiation, likely reflecting partial geographic isolation between species. Populations had a distribution pattern consistent with north-to-south "stepping-stone" dispersal with significant isolation by distance (IBD), similar to other tomato species. Several AFLP loci showed evidence of selection and associated with climate variables. However, phenotypic traits generally did not correlate with climate variables.


CONCLUSIONS
Geographic features of the coastal Andes is likely an important factor that determines the migration pattern and population structure of S. peruvianum, but climatic factors do not appear to be critical for its phenotypic evolution, perhaps due to a high degree of phenotypic plasticity. Spatial genetics of wild relatives of crop species is a powerful approach to understand their evolutionary patterns and to accelerate the discovery of their potential for crop improvements.
Department of Biological Sciences, The University of Memphis, Memphis, Tennessee 38152, USA. tnkazato@memphis.edu
Takuya
T
Nakazato
Robert A
RA
Franklin
Burton C
BC
Kirk
Elizabeth A
EA
Housworth
D054458:Amplified Fragment Length Polymorphism Analysis; D018744:DNA, Plant / Q000235:genetics; D019143:Evolution, Molecular; D005843:Geography; D010568:Peru; D010641:Phenotype; D063148:Plant Dispersal; D012641:Selection, Genetic; D032322:Solanum / Q000235:genetics*
D018744:DNA, Plant