Population Genomic Insights Into Recent Nutria (Myocastor coypus) Invasion Dynamics

Area of Science:

• Ecology
• Genetics
• Invasive Species Management

Background:

• Nutria (Myocastor coypus), invasive semi-aquatic rodents, cause significant agricultural and wetland damage.
• Eradicated from California in the 1970s, nutria have resurged in the Central Valley and Sacramento-San Joaquin Delta.

Purpose of the Study:

• To genetically characterize the source and demographic history of the current nutria invasion in California.
• To inform effective nutria eradication strategies.

Main Methods:

• Development of a novel SNP (single nucleotide polymorphism) dataset with 6809 loci.
• Analysis of mitochondrial DNA (cytochrome b locus).
• Multivariate analysis, Bayesian clustering, Mantel tests, and effective migration surface (eems) analysis.

Main Results:

• The current California nutria population shows greatest genetic similarity to invasive populations in central Oregon.
• A single contemporary California haplotype was detected, shared with Oregon, Washington, and historical fur farm samples.
• Genetic differentiation is influenced by riverine dispersal corridors and rapid expansion in wetland habitats.

Conclusions:

• California nutria represent a recent introduction with rapid expansion, likely originating from Oregon.
• The Central Valley should be managed as a single eradication unit.
• Targeting dispersal corridors is crucial for successful eradication.