Issues that remain
The improvements in the post-2020 GBF draft are laudable, and we believe reflect an increasing understanding among CBD policy makers regarding genetic diversity and its importance. However, the current wording misses some elements, and further refinement of the text is critically needed to retain key principles and ensure robust monitoring and reporting, while avoiding perverse incentives and potential loopholes (see Table 2).
Goal A currently includes maintenance of genetic diversity “within all species” or “within wild and domesticated species.” Either phrasing is suitable, as both emphasize that genetic diversity within all species matters (note: the word “within” should be used).
The ambition remains insufficient at 95%, as highlighted by Frankham (Frankham 2022), who showed that essentially no genetic diversity (specifically, heterozygosity) can be lost, e.g. 100% must be maintained. Still, a commitment to percentage may be problematic for two reasons. First genetic diversity can be assessed with numerous metrics (Ne, allelic richness, heterozygosity, adaptive genetic variance) and each is lost at different rates. Heterozygosity is the most common metric, but allelic richness declines much faster. Second, regardless of the metric, a percentage is hard to monitor temporally as only few thousand species globally have any population genetic data (DNA data from individuals across geographic space), and perhaps only a few dozen species globally have regular temporal DNA assessments. Most countries simply cannot accurately report a percentage of genetic diversity maintained.
The GBF may be better served by stating ‘maintain all within population genetic diversity and maintain all distinct populations,’ or ‘maintain sufficient genetic diversity within populations and maintain all distinct populations.’ For most populations, ‘sufficient’ will refer to no loss of current genetic diversity, or restored genetic diversity, and this can easily be reported using indicators for an effective population size of 500 to mitigate loss fom genetic drift. No loss is consistent with CBD’s Mission (“To take urgent action across society… to put biodiversity on a path to recovery by 2030 for the benefit of planet and people” and Vision (“living in harmony with nature”), especially as many species already suffered high genetic diversity loss (DiBattista 2008; Leigh et al. 2019; Exposito-Alonso et al. 2022). Ne ≥ 500 is important for all populations within species regardless of past losses.
A final issue continues to be ambiguous wording. Depending on wording retained, the Goal and Target might be confusing or contradictory. We suggest that the terms ‘safeguarded’ and ‘maintained’ may cause confusion and could be considered duplicative, unless it is made clear that safeguarded means ‘protected’ (in seed banks and in protected areas) and ‘maintained’ means ‘not lost .’ Two other similar words are ‘genetic diversity’ and ‘adaptive potential’; both terms are recommended by(Díaz et al. 2020; Hoban et al. 2020). Geneticists typically interpret ‘genetic diversity’ as genome-wide measures and ‘adaptive potential’ as diversity in functional genes, or more generally as the extent to which populations can evolve, which is a consequence of genetic diversity. The two are not duplicative or fully interchangeable. Retaining the wording ‘adaptive potential’ also emphasizes the need for future adaptation of populations to climate change, disease, and other challenges.