Table 2.
Proposed definitions of technical terms
| Term | Definition |
|---|---|
| Heterozygosity | A measure of genetic diversity that ranges from zero to one; higher values provide a buffer for populations during environmental change, and are correlated with higher fitness and survival |
| Allelic richness | The number of alleles—genetic variants—that exist. To simplify slightly, the more alleles, the more “options” a population or species has—the more various possible future environments it can adapt to. It is analogous to maintaining species diversity in an ecosystem |
| Genetic drift | The loss of genetic diversity to random chance—a sampling effect at each generation. Genetic drift is higher in smaller populations. Analogous to the loss of species in small fragments. Rare alleles are usually lost first |
| Effective population size (Ne) | A metric that measures the rate of loss of genetic diversity. Ne > 500 (or Ne > 1000, see Frankham 2014, 2022) is an approximate threshold value of this metric, below which genetic diversity is rapidly lost (see Fig. 2 in Willi et al. 2021)—resulting in populations that do not maintain adaptive potential. Ne is often ~ 1/10th the census size, thus Ne = 500 corresponds to census size of approximately 5000 |
| Genetic diversity | Genome-wide diversity existing in populations (also known as “standing genetic variation”). Standing genetic variation is a major contributor to adaptive potential |
| Adaptive potential | The ability of populations to evolve in response to environmental change, or the extent to which they can evolve. Adaptation occurs by changes in frequency of alleles that determine traits. Adaptive potential is a consequence of a large pool of genetic diversity and the size of the population. Typically, Ne=500 has been considered a minimum threshold to maintain adaptive potential |
| Safeguarded | To protect or make safe. In the context of biodiversity, to take actions to protect, for the long term, including in situ protected areas, ex situ gene banks, and other activities. The actions are designed to minimize harm |
| Maintained | To keep at the current state with respect to diversity level; prevent any decline or loss or diversity |
| Population | A geographically, genetically, ecologically, and/or behaviorally coherent and distinct group of individuals of a species |