Conservation genomic investigation of an endangered conifer, , reveals low genetic diversity but also low genetic load.

Endangered species generally have small populations with low genetic diversity and a high genetic load. is an endangered conifer endemic to southwestern China. It was once considered extinct in the wild, but in 1999 was rediscovered. However, little is known about its genetic load. We collected 67 individuals from five wild, isolated populations, and used 636,151 SNPs to analyze the level of genetic diversity and genetic load in to delineate the conservation units of , based on whole transcriptome sequencing data, as well as target capture sequencing data. We found that populations of could be divided into three groups. These groups had low levels genetic diversity and were moderately genetically differentiated Our findings also indicate that suffered two severe bottlenecks around the Last Glaciation Period and Last Glacial Maximum. Among species, presented the lowest genetic load and hence might have purged deleterious mutations efficiently through purifying selection. However, distribution of fitness effects analysis indicated a high extinction risk for . Multiple lines of evidence identified three management units for . Although possesses a low genetic load, low genetic diversity, suboptimal fitness, and anthropogenic pressures all present an extinction risk for this rare conifer. This might also hold true for many endangered plant species in the mountains all over the world.