Genetic Diversity and Structure Analysis of Percocypris pingi (Cypriniformes: Cyprinidae): Implications for Conservation and Hatchery Release in the Yalong River

Abstract

Percocypris pingi is a near threatened cyprinid species, which has suffered a dramatic decline due to anthropogenic factors. As one response to this decline, hatchery release for P. pingi has been conducted in the lower reaches of the Yalong River since 2012. To understand the conservation status of this species and the potential impact of the release of hatchery-reared fish, we studied the genetic diversity and population structure of wild and hatchery populations of P. pingi. Two hatchery populations (Jinping [JPH] and Ya’an [YAH]) and two wild populations (Muli [MLW] and Woluo [WLW]) of P. pingi were analyzed based on microsatellite markers and the mitochondrial DNA control region. The results showed that P. pingi possesses moderate levels of genetic diversity, with observed heterozygosities ranging from 0.657 to 0.770 and nucleotide diversities ranging from 0.00212 to 0.00491. Our results also suggested WLW harbors considerable proportions of genetic diversity in this species and serves as a refuge for P. pingi during anthropogenic disturbance, thus playing an important role for the conservation of P. pingi populations. Microsatellite and mitochondrial markers both indicated close genetic relationships between YAH and MLW, JPH and WLW, respectively. The results to some extent reflected the geographical provenances for original broodstocks of the two hatchery populations, which provide some practical guidance for hatchery release of P. pingi. The existence of remarkable genetic divergence distributed along limited geographical range (approximately 10 kilometers) suggests the two wild populations should be regarded at least as two distinct evolutionary significant units (ESUs) and management units (MUs). Considering reduced intra-population genetic variation in hatchery population for release and significant genetic compositions of the two hatchery populations, some appropriate breeding strategies were proposed to benefit conservation of P. pingi.

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“…Some previous studies have reported some adverse genetic effects caused by releasing hatchery-produced individuals in restocking programs (Cheng et al, 2011;Li et al, 2016). Here, despite the high level of heterozygosity, the wild populations of R. kutum showed lower level of allelic diversity and a sign of genetic bottleneck.…”

Genetic variability in wild and hatchery populations of commercially important fish: The common carp (Cyprinus carpio)

“…A reduction in the number of unique alleles was also observed in the hatchery samples. Genetic diversity reduction in fish hatchery populations has been previously demonstrated (Li et al 2016;Wenne et al 2016). Selection, breeding with limited number of parents and consequently inbreeding depression appeared to be the main explanations for the decrease in genetic diversity of hatchery populations (Li et al 2016).…”

“…Genetic diversity reduction in fish hatchery populations has been previously demonstrated (Li et al 2016;Wenne et al 2016). Selection, breeding with limited number of parents and consequently inbreeding depression appeared to be the main explanations for the decrease in genetic diversity of hatchery populations (Li et al 2016). Tessier et al (1997) also reported high genetic drift and 50% reduction of effective population size in hatchery populations of Atlantic salmon due to the very small number of parents used for establishing hatchery population.…”

“…However, despite the potential benefits, restocking through the supportive breeding may lead to possible problems including increase in genetic divergence between sites due to genetic drift and decrease in genetic variability (Roodt-Wilding 2007). Such adverse genetic effects on natural population restoration have been previously reported by Araki et al 2007;Cheng et al 2011 andLi et al 2016. Nevertheless, there have also been reports on maintaining genetic variability in hatchery populations of other fish species (Pan and Yang 2010;.…”

“…Since the genetic quality of hatchery-produced larvae may have a great impact on the efficiency of restocking programs (Li et al 2016), conservation management strategies without the knowledge of genetic structure can have deleterious impacts on the gene pools of natural populations (Laikre et al 2005). Food and Agricultural Organization of the nations also recommends genetic assessment of the populations used for restocking programs as well as the target ones to monitor any changes for sustainable management of populations.…”