Mapping collection bias in Brazil

An analysis of species occurrences in Brazil shows collection bias across biomes and taxonomic groups

Data resources used via GBIF : 509,983 species occurrences
Jaguar (Panthera onca)

Jaguar (Panthera onca) observed by Douglas Trent near Poconé, Mato Grosso, Brazil. Photo licensed under CC BY-NC 4.0.

Temporal and spatial variation in biological sampling may generate bias leading to shortfalls of biological knowledge, including undescribed species, poorly described species distribution, and a lack of information on tolerances and responses of species to e.g. climate changes.

In this study, researchers compiled a database of arthropod, vertebrate and angiosperm records in Brazil using data mainly from the GBIF network to test for sampling bias. Comparing taxonomic groups, they find significant differences in sampling effort with angiosperms having larger areas of high density than arthropods and vertebrates. Across all groups and biomes, however, the highest density of records falls within one kilometre of access routes, and this density increases with number of routes.

The study notes the importance of considering such collection bias in biogeographic studies, and suggests focusing on poorly sampled locations in future biodiversity surveys.



Oliveira U, Paglia AP, Brescovit AD, de Carvalho CJB, Silva DP, Rezende DT, Leite FSF, Batista JAN, Barbosa JPPP, Stehmann JR, Ascher JS, de Vasconcelos MF, De Marco P, Löwenberg-Neto P, Dias PG, Ferro VG and Santos AJ (2016) The strong influence of collection bias on biodiversity knowledge shortfalls of Brazilian terrestrial biodiversity. Diversity and Distributions. Wiley-Blackwell 22(12): 1232–1244. Available at: