Temporal lags in observed and dark diversity in the Anthropocene

Abstract

Understanding biodiversity changes in the Anthropocene (e.g. due to climate and land‐use change) is an urgent ecological issue. This important task is challenging because global change effects and species responses are dependent on the spatial scales considered. Furthermore, responses are often not immediate. However, both scale and time delay issues can be tackled when, at each study site, we consider dynamics in both observed and dark diversity. Dark diversity includes those species in the region that can potentially establish and thrive in the local sites’ conditions but are currently locally absent. Effectively, dark diversity connects biodiversity at the study site to the regional scales and defines the site‐specific species pool (observed and dark diversity together). With dark diversity, it is possible to decompose species gains and losses into two space‐related components: one associated with local dynamics (species moving from observed to dark diversity and vice versa) and another related to gains and losses of site‐specific species pool (species moving to and from the pool after regional immigration, regional extinction or change in local ecological conditions). Extinction debt and immigration credit are useful to understand dynamics in observed diversity, but delays might happen in species pool changes as well. In this opinion piece we suggest that considering both observed and dark diversity and their temporal dynamics provides a deeper understanding of biodiversity changes. Considering both observed and dark diversity creates opportunities to improve conservation by allowing to identify species that are likely to go regionally extinct as well as foreseeing which of the species that newly arrive to the region are more likely to colonize local sites. Finally, by considering temporal lags and species gains and losses in observed and dark diversity, we combine phenomena at both spatial and temporal scales, providing a novel tool to examine biodiversity change in the Anthropocene.

Dark diversity at home describes the success of cross‐continent tree invasions

“…with SLS). AM, arbuscular mycorrhizal; AM+ECM, dual mycorrhizal; ECM, ectomycorrhizal; FM, facultative mycorrhiza; OM, obligate mycorrhizal understanding complex ecological dynamics across different spatial scales (Trindade et al, 2020), including biological invasions.…”

Integrating dark diversity and functional traits to enhance nature conservation of epiphytic lichens: a case study from Northern Italy

“…Second, as community completeness is lower at low elevations, in the short-term, restoration practices could facilitate the colonization and establishment of species currently in dark diversity, thus increasing completeness. However, warming scenarios might impose important challenges to species at low elevations, since the filters are already stronger and the species pool size is small, suggesting that long-term conservation strategies should focus on the entire species pool to prevent species losses in both observed and dark diversity (Trindade et al 2020). Finally, the increasing difference between observed and dark diversity along the elevational gradient suggests that, under a warming scenario, observed diversity will likely decrease faster than dark diversity.…”

Widespread homogenization of plant communities in the Anthropocene

“…Habitat conversion, biotic invasions, anthropogenic climate change, and pollution have contributed initially to dark diversity 1 and eventually to global species losses 2 – 5 . There has been much focus on species extinctions 6 , 7 ; however, how these biodiversity changes manifest at local to regional scales is still unclear: some studies show declining local diversity 8 , while others suggest stable or even increasing species diversity through time 9 , and changes in the turnover of species diversity (β-diversity) have been less well studied.…”