The number of Red-Listed animal species in each country relative to the number of biodiversity studies.

<p>Dividing the number of animal species threatened with extinction [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0189577#pone.0189577.ref019" target="_blank">19</a>] by the number of biodiversity studies reveals regions that are understudied given their number of threatened species. Countries in northern South America, Africa and SE Asia stand out as being relatively understudied; much of central Africa lacked studies altogether in this sample. Darker colours represent a higher number of listed threatened species per study.</p

The phrasing of papers’ titles differs between taxonomic groups.

<p>The majority of studies on vertebrates (with the exception of studies on fishes) do not mention the study taxon in the title. Conversely, for papers on invertebrates, the taxa being studied were specified more often than not.</p

Number of authors and lead authors per million people for each country.

<p>The number of authors (a) and lead authors (b) from each country relative to the country’s population. Many countries in Africa, central Asia and South America lacked authors on the papers in the sample.</p

The proportions of different animal taxa studied in biodiversity research over the last 20 years.

<p>The proportion of different taxonomic groups in the sample of papers with ‘biodiversity’ in the title is shown for 4 five-year periods since 1996. For comparison, the right-hand column illustrates the ‘true’ proportions of described species that each group makes up (data from IUCN [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0189577#pone.0189577.ref020" target="_blank">20</a>]) Vertebrate and invertebrate taxa are separated by a grey line.</p

Representation of different animal groups in temperate and tropical biodiversity studies.

<p>The bias towards vertebrates is greater in tropical regions than temperate regions. The proportions of described species in different groups are shown in the right-hand column for comparison.</p

The global distribution of biodiversity research by country.

<p>The number of papers with ‘biodiversity’ in the title per 1000km² is shown, for a) papers that study vertebrates and b) papers that study invertebrates. Darker colours represent a higher density of studies.</p

The number of biodiversity papers in a country related to its GDP.

<p>Nominal GDP in US$ is plotted against the number of biodiversity studies sampled from each country, revealing a positive relationship. The top ten countries for number of papers are labelled. Many countries with low GDP had no biodiversity papers identified from this sample.</p