Abstract
The giant panda is an example of a species that has faced extensive historical habitat fragmentation, and anthropogenic disturbance and is assumed to be isolated in numerous subpopulations with limited gene flow between them. To investigate the population size, health, and connectivity of pandas in a key habitat area, we noninvasively collected a total of 539 fresh wild giant panda fecal samples for DNA extraction within Wolong Nature Reserve, Sichuan, China. Seven validated tetra‐microsatellite markers were used to analyze each sample, and a total of 142 unique genotypes were identified. Nonspatial and spatial capture–recapture models estimated the population size of the reserve at 164 and 137 individuals (95% confidence intervals 153–175 and 115–163), respectively. Relatively high levels of genetic variation and low levels of inbreeding were estimated, indicating adequate genetic diversity. Surprisingly, no significant genetic boundaries were found within the population despite the national road G350 that bisects the reserve, which is also bordered with patches of development and agricultural land. We attribute this to high rates of migration, with four giant panda road‐crossing events confirmed within a year based on repeated captures of individuals. This likely means that giant panda populations within mountain ranges are better connected than previously thought. Increased development and tourism traffic in the area and throughout the current panda distribution pose a threat of increasing population isolation, however. Maintaining and restoring adequate habitat corridors for dispersal is thus a vital step for preserving the levels of gene flow seen in our analysis and the continued conservation of the giant panda meta‐population in both Wolong and throughout their current range.
Highlights
Rare and elusive large‐bodied mammal populations intrinsically occur at low densities (Mumma, Zieminski, Fuller, Mahoney, & Waits, 2015; Taberlet & Bouvet, 1992) and face increasing threats from cli‐ mate change and anthropogenic influences (Li et al, 2015; Zhu et al, 2013)
Previous capture/recapture studies of giant pandas that have used genetic markers have resulted in population size estimates that have exceeded those of other methods, with Zhan et al (2006) estimat‐ ing nearly double the population size in Wanglang Nature Reserve compare to the 3rd national survey
Our CMR model estimate of giant panda population size within Wolong was larger than results from the latest national survey, though not as drastically so
Summary
Rare and elusive large‐bodied mammal populations intrinsically occur at low densities (Mumma, Zieminski, Fuller, Mahoney, & Waits, 2015; Taberlet & Bouvet, 1992) and face increasing threats from cli‐ mate change and anthropogenic influences (Li et al, 2015; Zhu et al, 2013). There is evidence of recent population recovery which re‐ sulted in the reduction of their extinction risk on the IUCN red list (Swaisgood, Wang, & Wei, 2017), pandas still face ongoing increases in habitat fragmentation and subpopulation isolation (Xu et al, 2017; Yang et al, 2017) Their occupancy has been reduced to the eastern edge of the Tibetan plateau in six separate mountain ranges (Schaller, Hu, Pan, & Zhu, 1985). While roads cover seemingly small proportions of land surface, they affect the environment in various ways, such as through the loss of suitable habitat, animal mortality, acting as barriers to individual movements, and causing landscape fragmentation (Balkenhol & Waits, 2009; Fahrig, 2004; Zhao et al, 2016) These effects can act to increase genetic structure between populations and decrease genetic diversity within populations, which further reduces population viability (Keyghobadi, 2007). We expect our results to have implications for the conservation of remaining giant panda populations both within Wolong and throughout their range
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