Taxonomic bias, i.e. the fact that some taxa are more investigated than others, is a well-known problem for the study of biodiversity. Describing and understanding these taxonomic biases and their causes are crucial for us to be able to set up effective policies for biodiversity conservation.
In a recent study researchers quantify the relative impact of taxonomic research and societal preferences on taxonomic bias in data from GBIF. Using a range of measures the researchers assessed both bias and precision across 626 million GBIF-mediated occurrences representing one million species.
The results of the study show that the number of recorded species per taxonomic group was not proportional to their known species richness, highlighting a strong taxonomic bias. By comparing the number of species with occurrences, with known species richness within each investigated taxonomic group, they found birds and insects to be the most over- and under-represented, respectively. This bias is not new, but recent growth in data also shows that this gap is growing larger. The researchers write that “Given that these neglected organisms have a high diversity and play crucial roles in diverse ecosystems this situation will inevitably result in an unbalanced fundamental knowledge of biodiversity, risky guesses and uninformed conservation decisions”.
After performing a similar, although simplified, analysis of the GBIF mediated data available for Sweden we can present results congruent with their study. The results are presented in the figure below: The vertical line at x = 0 shows the ‘ideal’ number of occurrences per taxonomic group, where each class is sampled proportionally to its number of known resident species. Green and red bars show the groups that are over- and under-represented in the GBIF mediated data available for Sweden compared to the ‘ideal’ sampling, respectively. Insects lack >26 million occurrences and birds have an excess of >35 million occurrences compared to an unbiased taxonomic sampling. The taxonomic groups selected are based on the GBIF country report for Sweden.