Population genomic analysis suggests strong influence of river network on spatial distribution of genetic variation in invasive saltcedar across the southwestern United States

• Published in: Molecular ecology Vol. 27; no. 3; pp. 636 - 646
• Main Authors: Lee, Soo‐Rang, Jo, Yeong‐Seok, Park, Chan‐Ho, Friedman, Jonathan M., Olson, Matthew S.
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01-02-2018
• Subjects: Anthropogenic factors; Colonization; Dispersal; Genetic diversity; Genetic structure; Genetic Variation; Genetics, Population; Genomic analysis; Geography; Human influences; Introduced Species; Invasive species; Landscape; landscape genomics; Low temperature; Models, Genetic; Natural selection; Polymorphism, Single Nucleotide - genetics; Population; Population genetics; population structure; Populations; range expansion; Range extension; Riparian environments; River basins; River networks; River systems; Rivers; Similarity; Single-nucleotide polymorphism; Southwestern United States; Spatial distribution; Tamaricaceae - genetics; Tamarix; Tamarix africana; Southwestern United States; United States > US; landscape genomics; range expansion; population structure; invasive species; Tamarix
• ISSN: 0962-1083; 1365-294X
• DOI: 10.1111/mec.14468

Understanding the complex influences of landscape and anthropogenic elements that shape the population genetic structure of invasive species provides insight into patterns of colonization and spread. The application of landscape genomics techniques to these questions may offer detailed, previously undocumented insights into factors influencing species invasions. We investigated the spatial pattern of genetic variation and the influences of landscape factors on population similarity in an invasive riparian shrub, saltcedar (Tamarix L.) by analysing 1,997 genomewide SNP markers for 259 individuals from 25 populations collected throughout the southwestern United States. Our results revealed a broad‐scale spatial genetic differentiation of saltcedar populations between the Colorado and Rio Grande river basins and identified potential barriers to population similarity along both river systems. River pathways most strongly contributed to population similarity. In contrast, low temperature and dams likely served as barriers to population similarity. We hypothesize that large‐scale geographic patterns in genetic diversity resulted from a combination of early introductions from distinct populations, the subsequent influence of natural selection, dispersal barriers and founder effects during range expansion.