Map of Life

Solutions

About

Press & Media

Resources

Solutions

About

Press & Media

Resources

Species Information Index

EXPLORE THE MAP

OVERVIEW

MEDIA & PRESENTATIONS

METHODS

SOURCES

CITATIONS & ACKNOWLEDGEMENTS

Overview

Species occurrence records are essential for a detailed understanding of the distribution of biodiversity in space and time. Yet, despite an impressive recent growth and now hundreds of millions of accessible records, the ability of this information to represent biodiversity and its change has remained largely unquantified. The Species Information Index (SII) assesses how adequately this publicly available species data inform about the status and trends of biodiversity. The SII is calculated annually across tens of thousands of terrestrial vertebrate species.

The SII assesses the taxonomic, spatial, and temporal coverage of publicly available species occurrence records. It was introduced by Oliver et al. (2021) and is maintained by Map of Life. The Map of Life calculations are based on species data available on the Global Biodiversity Information Facility (GBIF), but the calculation can be performed independently by any country with national biodiversity monitoring data to assess existing data coverage and inform future biodiversity monitoring needs.

The SII was developed under the auspices of the GEO Biodiversity Observation Network and part of the Biodiversity Indicators Partnership and is formally adopted in the Global Biodiversity Monitoring Framework as a complementary indicator for Target 21, which stipulates that “best available data, information and knowledge are accessible to decision makers, practitioners and the public.”

The integrity of ecosystems is broadly defined by the status of their component species and the ecological processes they support and require. Integrity can be assessed by the degree of change (loss and gain) in the set of species and associated processes observed within an ecosystem and its habitats. The Species Habitat Index (SHI) measures this change and captures alterations in the ecological intactness of ecosystems. The SHI is calculated annually across tens of thousands of terrestrial vertebrate species.

The index measures changes in the estimated size, connectivity and quality of species habitats. The index uses species as core units of analysis, thereby capturing the individual ecological processes associated with species that are central to ecosystem integrity. The index uses spatially explicit information at a resolution of single pixels (1 km2) to support aggregate measures of the ecological integrity of defined geographic units. Given the species-level nature of the metric, SHI informs about trends in species population size, distribution, health, and, as proxy, genetic diversity.

A METRIC OF

SPECIES MONITORING

COMPONENT INDCATOR OF

TARGET 21

TAXONOMIC COVERAGE

TERRESTRIAL:

The SHI was developed under the auspices of the GEO Biodiversity Observation Network and part of the Biodiversity Indicators Partnership and is formally adopted in the Global Biodiversity Monitoring Framework as a component indicator for Goal A, which stipulates that the "integrity, connectivity and resilience of all ecosystems" be "maintained, enhanced, or restored" by 2050.

Media & Presentations

Methods

All data and scripts to support Oliver et al. 2021 can be found in the following GitHub repository: https://github.com/MapofLife/biodiversity-data-gaps

Taxonomic harmonization

To prevent missing or double-counting species due to synonymy, all scientific names in GBIF and range map datasets are harmonized under common taxon concepts. For this purpose, we carefully developed synonym lists to match species names in GBIF-mediated data to names used for the expert information. For each major species group, we selected a well-curated taxonomic database as our ‘master taxonomy’, that defines accepted species delimitations. To each accepted species name, we linked additional scientific names that are fully or partly included in the respective taxon concept, including synonyms, subspecies, and typographical variants and spelling mistakes. To be able to interpret all scientific names in range map and GBIF datasets, we integrated our master taxonomies with various additional sources of scientific names. Any remaining non-matching names were matched using approximate string matching and afterwards individually validated.

Scientific name resolution

The SII considers species native ranges only. To validate records geographically, we excluded any records that fell outside of the respective species’ known extents of native occurrence (as inferred from gridded range maps). A major problem with records in aggregative databases is that the originally intended taxon concepts behind ambiguous scientific names (such as many pro parte synonyms) are typically unknown. However, these can often be inferred indirectly from records’ geographical locations. Here, we do so by inferring taxonomic identities of ambiguously named records through spatial overlays with the range maps of all accepted species to which these names could potentially refer. In cases where ambiguously named records overlap with ranges of more than one ‘candidate’ accepted species, we assume that these names reflect the taxon concepts in our master taxonomy. If ambiguities still persist, we assume that all records of a given ambiguous name in a given grid cell refer to only one of the candidate accepted species, hence our completeness index may be slightly conservative in these cases.

Species-level scores

The SII calculation is based on individual species information scores (SIS). The SII measures how well the existing data covers a species’ expected range. A global equal area grid (ca. 110-km resolution) is overlaid on the species expert range to give the gridded expected range, then the SIS is simply calculated as the proportion of total grid cells that contain a documented occurrence point in a given year. This calculation can be performed across the species entire global range or across just the portion of range within a given country.

For example, a species whose range covers ten grid cells will have an SIS of 50 if exactly five of those cells contain at least one occurrence point.

National SII

A country’s national SII is calculated as the simple average of the within-country SIS values across all species. The national SII can also be computed as a weighted mean where each species is weighted by stewardship, or the percent of its range that is within the country. The SII therefore measures how well, on average, species occurrence data cover the expected ranges of species within a country across a given year from 0 to 100. A large number of occurrence records will not necessarily lead to a high SII if those records poorly represent biodiversity, for example, if the data is repeatedly coming from just a small portion of species or locations. The SII may fluctuate significantly between years.

Sources

For the latest 2024 version of the SII:

Species Range Maps

Species Group

Source

Amphibians

IUCN (2016). The IUCN Red List of Threatened Species. International Union for Conservation of Nature. Accessed on January 2017. Downloaded at www.iucnredlist.org

Birds

Jetz, W., et al. (2012). The global diversity of birds in space and time. Nature, (491);444-448. doi.org/10.1038/nature11631

Mammals

Mammal Diversity Database. (2020). Mammal Diversity Database (Version 1.2) [Data set]. Zenodo. doi.org/10.5281/zenodo.4139818. Map of Life. (2021). Mammal range maps harmonised to the Mammals Diversity Database [Data set]. Map of Life. doi.org/10.48600/MOL-48VZ-P413

Reptiles

Roll, U. and Meiri, S. (2022). GARD 1.7 - updated global distributions for all terrestrial reptiles [Dataset]. Dryad. doi.org/10.5061/dryad.9cnp5hqmb

Terrestrial vertebrates

Misc. literature and expert sources