生態学：幅広い生物種における遺伝的多様性の減少

Genetic diversity has declined within more than 600 species over the past three decades, according to research published in Nature. The findings highlight the need for conservation efforts to prevent genetic diversity loss.

The population decline and fragmentation of species due to human activity can result in decreasing genetic diversity within species, which can threaten their long-term fitness and survival. Such human-driven factors include extreme climatic events, habitat destruction and the introduction of invasive species. Prediction of genetic diversity change is crucial when designing ecological interventions to combat species loss; however, there are limited data on the extent and patterns of genetic diversity loss.

Catherine Grueber and colleagues undertook a systematic review of 882 studies measuring genetic diversity changes between 1985 and 2019. The dataset covered 628 species, which included animals (84.7%), plants (12.7%), fungi (1.9%) and chromists (0.6%). Genetic diversity loss was observed across the majority (90.2%) of terrestrial species, losses in marine realms were more variable. The greatest losses of genetic diversity were observed in birds and mammals.

The authors also categorized the effects of threats and intervention efforts on the genetic diversity of populations. They found that two-thirds of populations experienced at least one type of ecological disturbance. Diversity decline was also observed in species that did not suffer any ecological disturbance, suggesting a background level of decline that was not triggered by a specific event. Less than half of the populations impacted by threats were the subject of conservation efforts. Analysis of conservation efforts reported to have occurred within the study periods suggested their potential to slow or halt the loss of genetic diversity within affected populations, with supplementation (the addition of new individuals to a species population) being the only intervention to show an accompanying increase in genetic diversity over time.  

These results highlight the need for targeted interventions to slow the loss of genetic diversity associated with human activity and could be used to target such efforts to maximum effect.