Genetic Diversity and Population Structure of Nutria (Myocastor coypus) in South Korea

Abstract

The nutria (Myocastor coypus) is an invasive alien species that have had major adverse effects on biodiversity and the agricultural economy in wetland habitats. Since 2014, the Ministry of Environment in South Korea has been carrying out the Nutria Eradication Project, and we investigated nutria distribution and genetic diversity of nutria populations in South Korea. We estimated that 99.2% of nutria habitats are in the mid-lower Nakdong River regions. To further analyze the genetic diversity in eight major nutria populations, we performed a genetic analysis using microsatellite markers. Genetic diversity levels of the eight nutria populations in South Korea were relatively lower than those in other countries. The probability of migration direction among nutria populations was predicted from genetic distance analysis. Genetic structure analysis showed little difference among the nutria populations in South Korea. These results suggest that nutrias in South Korea originated from a single population. Our results provide important data for establishing management strategies for the successful eradication of nutria populations in South Korea, as well as in other countries with alien invasive species.

Keywords: Myocastor coypus; genetic diversity; invasive species; nutria; population structure.

Figure 1

Maps of the nutria survey areas. Red dots represent nutria farming sites (2002–2013) and the yellow-colored area is the survey area in this study.

Figure 2

Procedure for DNA extraction and microsatellite genotyping from nutria individuals. (A) nutria in nature, (B) cage traps of nutria, (C) nutria tissue sampling for DNA extraction (red circle), (D) amplification of microsatellite region using fluorescent-labeled primer sets, (E) analysis of amplified fragment, (F) examples of results of genetic diversity and genetic structure.

Figure 3

Kernel density using four different radii. (A) Red dot: habitat traces; (B) default: using the default value for kernel function bandwidth; (C) h_ref: calculated by the reference method used for kernel function bandwidth; (D) LSCVh: calculated by Least Squares Cross-Validation used for kernel function bandwidth; (E) CVh: calculated by Cross-Validation used for kernel function value.

Figure 4

Locations of sample collection sites from high-density nutria habitat tracks. CVh 0.1% high-density area (orange-colored region).

Figure 5

Nutria population structure analysis results. Each population is separated by a vertical bar. Abbreviations for populations are shown under panels. (A) STRUCTURE bar plot for K = 2, showing the same structures in eight populations; (B) Four groups identified by BAPS. Group 1: BUS, CHA, GIM, and YAN; Group 2: BAE and MIO; Group 3: JIN; Group 4: MIY.