Background
Genetic diversity (GD) quantifies the variation of genes within species,
variation which occurs within and among populations (Hoban et al.,
2022). GD therefore determines species’ resilience and evolutionary
potential, e.g. their ability to adapt to changing environmental
conditions (Sgrò et al., 2011). Higher GD within a species increases the
chance of the species to adapt to new conditions. Inversely, lower GD
within a species increases its risk of extinction (Spielman, Brook and
Frankham, 2004). GD also plays an important role in maintaining a
variety of biodiversity benefits to humanity such as ecosystem
resilience, food, medicine, energy, culture, and well-being (see Des
Roches et al., 2021 for a review).
Phylogenetic diversity (PD) quantifies the evolutionary history captured
by a set of species, as the sum of branch lengths connecting those
species across the phylogenetic tree representing their evolutionary
relationships (Faith, 1992). PD therefore represents the diversity of
evolutionarily inherited features across the Tree of Life, which
constitutes a reservoir of both current and yet-to-be discovered
benefits for future generations – a notion referred to as biodiversity
option value (IPBES, 2019). PD can best be maintained through
prioritising the conservation of evolutionarily distinct lineages to
effectively safeguard the Tree of Life, such as the those highlighted
within the EDGE (Evolutionarily Distinct and Globally Endangered)
species framework (Gumbs et al., 2022).
GD and PD respectively represent species’ evolutionary potential and
history, and support most of the biodiversity benefits to humanity. Yet,
these two biodiversity facets have been overlooked in previous
biodiversity policies (Cook & Sgrò, 2017; Hoban, Campbell, et al.,
2021; Robuchon et al., 2021). Specifically, while PD was fully excluded
from the strategic plan 2011-2020 of the Convention on Biological
Diversity (CBD), GD was recognised (e.g. Aichi Target 13) but
interpreted narrowly (Hoban, Campbell, et al., 2021), mainly addressing
GD of domesticated species (only a small fraction of all species).
Moreover, many countries neglected to develop monitoring strategies with
adequate indicators for GD and/or largely focused on ex situ conservation, overlooking in situ actions (Hoban et al., 2020).
This was partly due to the fact that the information regarding how (and
why) to conserve and monitor GD in practice was inaccessible to
policymakers and managers, and partly due to lack of GD indicators (Cook
& Sgrò, 2017; Hoban, Campbell, et al., 2021; Hoban et al., 2013; Taylor
et al., 2017). However, the situation has recently changed. For PD, the
Intergovernmental Platform for Biodiversity and Ecosystem Services
(IPBES) now recognises PD as an indicator of “maintenance of options”
and “medicinal, biochemical and genetic resources” (IPBES, 2019). For
GD, numerous recent advances in knowledge, technology, databases,
practice, and capacity now make global commitments for conserving and
monitoring GD feasible (Hoban, Bruford, et al., 2021). As the Parties to
the Convention on Biological Diversity (CBD) plan to meet in December
2022 in Montréal to agree on a new post-2020 global biodiversity
framework (GBF), we briefly analyse how GD and PD are currently
considered in this new framework and discuss the opportunities this
brings for strengthening their conservation.