Abstract Detail

Biodiversity Informatics & Herbarium Digitization

The commonness of rarity: Global and future distribution of rarity across land plants.

Background/Question/MethodsA key feature of life’s diversity is that some species are common but many more are rare. Nonetheless, at global scales, we do not know what fraction of biodiversity consists of rare species. Rare species are orders of magnitude more likely to go extinct, making it puzzling how so many rare species can be maintained. Understanding rarity and the maintenance of rare species is also central to conservation biology and to understanding current and future changes in biodiversity due to global change. Despite this importance, we know unexpectedly little about the causes of commonness and rarity and their maintenance at a global scale Here, we use a global botanical database of unprecedented coverage to (i) assess global patterns of plant rarity, (ii) test several proposed hypotheses underlying the generation and persistence of rare species, (iii) identify regions that harbor hotspots of rare species and explore the drivers of these spatial patterns, and (iv) assess how current patterns of human impact and future climate change scenarios may affect plant diversity via impacts on rare species. For all known land plants (Embryophyta), we have compiled a global database of standardized botanical observation records—the integrated Botanical Information and Ecology Network (BIEN); http://bien.nceas.ucsb.edu/bien/. Together, these data constitute more than 200 million observations of plant species occurrences. Results/Conclusions A large fraction, ~36.5% of Earth’s ~435,000 plant species, are exceedingly rare. Sampling biases and prominent models, such as neutral theory and the k-niche model, cannot account for the observed prevalence of rarity. Our results have important implications for conservation in the face of climate change and other human impacts. If ~36% of species are rare and threatened, then ~158,000 plant species are at risk of extinction. In addition, our analyses show that rapid rates of current human impact and projected future climate change appear to disproportionately affect regions that harbor most of these rare species, whereas the rare species likely have been in relatively more stable climates through their evolutionary history. Our results indicate that (i) climatically more stable regions have harbored rare species and hence a large fraction of Earth’s plant species via reduced extinction risk but that (ii) climate change and human land use are now disproportionately impacting rare species. Estimates of global species abundance distributions have important implications for risk assessments and conservation planning in this era of rapid global change.

1 - BioSciences West, Tucson, AZ, 85719, United States

Keywords:
Biodiversity Informatics
rarity
Biodiversity
Extinction
Macroecology.

Presentation Type: Oral Paper
Session: BIHD1, Biodiversity Informatics & Herbarium Digitization I
Location: Virtual/Virtual
Date: Wednesday, July 29th, 2020
Time: 3:45 PM
Number: BIHD1004
Abstract ID:257
Candidate for Awards:None