Frozen in time: Rangewide genomic diversity, structure, and demographic history of relict American chestnut populations.
Mol Ecol
; 31(18): 4640-4655, 2022 09.
Article
em En
| MEDLINE
| ID: mdl-35880415
ABSTRACT
American chestnut (Castanea dentata) was once the most economically and ecologically important hardwood species in the eastern United States. In the first half of the 20th century, an exotic fungal pathogen-Cryphonectria parasitica-decimated the species, killing billions of chestnut trees. Two approaches to developing blight-resistant American chestnut populations show promise, but both will require introduction of adaptive genomic diversity from wild germplasm to produce diverse, locally adapted restoration populations. Here we characterize population structure, demographic history, and genomic diversity in a range-wide sample of 384 wild American chestnuts to inform conservation and breeding with blight-resistant varieties. Population structure analyses suggest that the chestnut range can be roughly divided into northeast, central, and southwest populations. Within-population genomic diversity estimates revealed a clinal pattern with the highest diversity in the southwest, which likely reflects bottleneck events associated with Quaternary glaciation. Finally, we identified genomic regions under positive selection within each population, which suggests that defence against fungal pathogens is a common target of selection across all populations. Taken together, these results show that American chestnut underwent a postglacial expansion from the southern portion of its range leading to three extant genetic populations. These populations will serve as management units for breeding adaptive genetic variation into the blight-resistant tree populations for targeted reintroduction efforts.
Palavras-chave
Texto completo:
1
Bases de dados:
MEDLINE
Assunto principal:
Doenças das Plantas
/
Fagaceae
Tipo de estudo:
Prognostic_studies
/
Risk_factors_studies
Idioma:
En
Revista:
Mol Ecol
Assunto da revista:
BIOLOGIA MOLECULAR
/
SAUDE AMBIENTAL
Ano de publicação:
2022
Tipo de documento:
Article
País de afiliação:
Estados Unidos