Microsatellite markers reveal genetic divergence among wild and cultured populations of Chinese sucker Myxocyprinus asiaticus

Abstract

ABSTRACT. Studies of genetic diversity and genetic population structure are critical for the conservation and management of endangered species. The Chinese sucker Myxocyprinus asiaticus is a vulnerable monotypic species in China, which is at a risk of decline owing to fluctuations in effective population size and other demographic and environmental factors. We screened 11 microsatellite loci in 214 individuals to assess genetic differentiation in both wild and cultured populations. The single extant wild population had a higher number of alleles (13) than the cultured populations (average 7.3). High levels of genetic diversity, expressed as observed and expected heterozygosity (H O = 0.771, H E = 0.748, respectively), were found in both wild and cultured populations. We also report significant differentiation among wild and cultured populations (global F ST = 0.023, P < 0.001). Both STRUCTURE analysis and neighbor-joining tree revealed three moderately divergent primary genetic clusters: the wild Yangtze population and the Sichuan population were each identified as an individual cluster, with the remaining populations clustered together. Twenty-two samples collected from the Yangtze River were assigned to the cultured population, demonstrating the efficacy of artificial propagation to avoid drastic reduction in the population size of M. asiaticus. These genetic data support the endangered status of the M. asiaticus and have implications for conservation management planning.

Hatchery release programme modified the genetic diversity and population structure of wild Chinese sucker (Myxocyprinus asiaticus) in the upper Yangtze River

“…Population W3 showed a close genetic relationship with H4 (F ST = 0.074), suggesting that some of the fish released from the Wanzhou Fisheries Research Institute were mainly distributed in the Chongqing reach of the Yangtze River. Similar close genetic relationships among the hatchery and wild M. asiaticus were confirmed also by Wu et al (2016) and Cheng et al (2016). It takes approximately 6 years for male and 8 years for female M. asiaticus to reach sexual maturity, and the history of restocking is long enough for the first batches of released juveniles to have produced their offspring and hence to have influenced the genetic structure of the wild population.…”

“…A moderate decrease in genetic diversity occurred after the hatchery release programme, in that h and π decreased from 0.958 to 0.947, and from 0.052 to 0.0218, respectively (Sun et al, 2004; Wu et al, 2016). The microsatellite analysis of this study (Ho = 0.605) and Cheng et al (2016) (Ho = 0.738) confirmed the high level of genetic diversity when compared with most freshwater species (Ho = 0.54) (DeWoody & Avise, 2000). The increased genetic diversity of population W4 after the hatchery release programme, which may have been caused by the release of local or non‐local hatchery stocks, indicated apparent augmentation of the genetic variation in this region.…”

“…This, combined with the small effective population size (Ne) of hatchery‐reared juveniles, can lead to inbreeding (Matusse et al, 2016). The positive inbreeding coefficients of the three hatchery populations (F IS = 0.201–0.392) suggested that inbreeding has already occurred in the hatchery stations, which is inconsistent with the previous studies (Cheng et al, 2016; Wu et al, 2016; Liu et al, 2018). Interbreeding between released and wild individuals may alter the genetic composition of receiving populations or even replace local wild fish owing to the release of huge numbers (Christie et al, 2012; Waples, Larson & Waples, 2016).…”

“…For the studies identified, the information on the sample locations, sample sizes (number of populations and individuals) and number of markers used were extracted and synthesized, and the overall results and conclusions were summarized. Lastly, the results of this analysis of genetic diversity and population differentiation were combined with the findings of three previous studies (Sun et al, 2004;Cheng et al, 2016;Wu et al, 2016) to evaluate the genetic influence of the hatchery release programmes on M. asiaticus. A scatter plot for diversity comparison was built in SPSS 24.0.0.0 (SPSS, Inc., Chicago, IL, USA).…”

“…Cheng et al (2016) and Wu et al (2016) studied the genetic characteristics of limited numbers of wild‐caught M. asiaticus after the hatchery‐release programme had begun. However, Cheng et al (2016) regarded 59 M. asiaticus collected from nine different sampling locations on the Yangtze River as one population, which could not reflect the genetic characteristics of the fish from specific reaches with such small sample sizes. Wu et al (2016) evaluated the genetic diversity of three wild populations based on mitochondrial control region sequences, but this lacked effective verification by other methods.…”