North-South Colonization Associated with Local Adaptation of the Wild Tomato Species Solanum chilense.
Mol Biol Evol
; 32(11): 2932-43, 2015 Nov.
Article
em En
| MEDLINE
| ID: mdl-26232423
After colonization population sizes may vary across the species range depending on environmental conditions and following colonizations. An interesting question is whether local adaptation occurs more frequently in large ancestral populations or in small derived populations. A higher number of new mutations and a lower effect of genetic drift should favor selection in large populations, whereas small derived populations may require an initial local adaptation event to facilitate the colonization of new habitats. Wild tomatoes are native to a broad range of different habitats characterized by variable abiotic conditions in South America, and represent an ideal system to study this interplay between demography and natural selection. Population genetic analyses and statistical inference of past demography were conducted on pooled-sequencing data from 30 genes (8,080 single nucleotide polymorphisms) from an extensive sampling of 23 Solanum chilense populations over Chile and Peru. We reveal first a north-south colonization associated with relaxed purifying selection in the south as shown by a decrease of genetic variation and an increasing proportion of nonsynonymous polymorphism from north to south, and population substructure with at least four genetic groups. Second, we uncover a dual picture of adaptation consisting of 1) a decreasing proportion of adaptive amino acid substitutions from north to south suggesting that adaptation is favored in large populations, whereas 2) signatures of local adaptation predominantly occur in the smaller populations from the marginal ranges in the south.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Solanum
/
Aclimatação
Tipo de estudo:
Risk_factors_studies
País/Região como assunto:
America do sul
/
Chile
Idioma:
En
Revista:
Mol Biol Evol
Assunto da revista:
BIOLOGIA MOLECULAR
Ano de publicação:
2015
Tipo de documento:
Article
País de publicação:
Estados Unidos