A predator's perilous persistence
In the temperate forests of Hebei Province, the Xiaozhangzi Nature Reserve protects the apex predator of this ecosystem: the North China leopard (Panthera pardus japonensis). This particular subspecies is endemic to China and represents the last of the leopards in the northern part of the country. Habitat loss and human activity have shattered their historic range, leaving behind small, isolated populations. Fewer than 400 individuals are estimated to survive in the wild. Xiaozhangzi is a sanctuary, but the leopards it protects carry the genetic scars of their species' decline.
Genetic analysis of leopard populations in this region reveals a startling lack of diversity. Scientists use a measure called expected heterozygosity (He) to gauge the genetic health of a population; for North China leopards in this eastern area, the value is just 0.65. This is significantly lower than other leopard subspecies and even lower than other North China leopard populations in the west-central Loess Plateau, which have an He value of 0.72. This genetic uniformity is the result of a population bottleneck, a sharp reduction in population size that leaves a limited gene pool for future generations. The consequence is that the surviving leopards are all closely related.
The consequences of low diversity
A population that lacks genetic variation is extremely vulnerable. Without a diverse array of genes, the population has a reduced capacity to adapt to environmental changes, such as new diseases or shifts in climate. The low genetic diversity at Xiaozhangzi results from habitat fragmentation, which prevents leopards from moving between different areas and breeding with unrelated individuals. This isolation leads to inbreeding.
Studies confirm that the leopard population shows signs of inbreeding pressure. While computer models suggest the population may not face immediate extinction within the next 100 years, they also predict a further 22% loss of genetic diversity over that time if conditions remain the same. Conservation efforts are focused on monitoring the leopards using tools like camera traps and, attempting to restore habitat connectivity. By creating safe corridors for the leopards to travel between fragmented habitats, conservationists hope to encourage gene flow and bolster the genetic health of this critically endangered predator.