Introduction

The giant panda (Ailuropoda melanoleuca ) is a vulnerable species endemic to China. Although China’s recent efforts have greatly increased the number and distribution of the wild population, the giant pandas is only distributed in six isolated mountains, namely Qinling Mountains, Minshan Mountains, Qionglai Mountains, Liangshan Mountains, Daxiangling Mountains and Xiaoxiangling Mountains (State Forestry Administration, 2006). The wild population is subject to different degrees of habitat fragmentation at each of the six mountains, and is further divided into more than 30 small populations (O’Brien et al., 1994; Loucks et al., 2001; Lü et al., 2001; Qing, 2016). Therefore, the giant panda is still at a great risk of extinction (Sichuan Provincial Forestry Department, 2015), particularly being vulnerable to stochastic processes. And thus a comprehensive understanding the population size and genetic health status of giant pandas in these region is crucial for the protection decision-making and conservation of this vulnerable species.
The Liangshan Mountains is the southernmost distribution of giant pandas and is located in the transition zone between the southwest edge of the Sichuan basin and the Qinghai Tibet Plateau. The transition zone is within a global biodiversity hotspot, is highly important for the protection of biodiversity in China and is crucial for giant panda protection (Fan et al., 2010). However, the Liangshan Mountains is outside the newly established Giant panda national Park (National Forestry and Grassland Administration (National Park Administration), 2019) (Figure 1). According to the fourth survey report on giant pandas, there are 124 giant pandas in the Liangshan Mountains and are mainly distributed in Heizhugou, Meigu and Mabian nature reserves (Sichuan Provincial Forestry Department, 2015) (Table 1). These three reserves are located in the heartland of the Liangshan Mountains, and thus are crucial for the protection of giant pandas in the Liangshan Mountains. However, the accurate number, genetic diversity, gene exchange and stable inheritance of panda populations in these key areas remain unclear. Understanding these issues will be vital to the protection of giant pandas in the Liangshan Mountains.
Microsatellite markers have become an important genetic markers in the field of molecular biology (Selkoe and Toonen, 2010) and have been widely used in population surveys (Creel et al., 2003; Piggott et al., 2006; Wang et al., 2016), genetic diversity assessments (Vanhala et al., 1998; Zhang et al., 2007; Shen et al., 2009; Li et al., 2010; Du et al., 2016), and genetic management of populations (Shan et al., 2014). The combined application of microsatellite markers, mitochondrial markers and non-invasive genetic sampling allows giant panda population studies without the risk of capture stress, injury or death, which has contributed greatly to giant pandas conservation in the past 20 years. Consequently, we used microsatellite markers and mitochondrial markers (D-loop) to accurately identify population size and assess the genetic traits of giant pandas in Heizhugou, Meigu and Mabian giant panda populations. We aimed to assess the genetic health status of giant pandas and provide reliable data for establishing genetic archives of giant panda populations and developing the genetic management of giant pandas across the Liangshan Mountains. This is the first extensive genetic survey of giant pandas in the Liangshan Mountains.