Sampling biases shape our view of the natural world

Spatial patterns of biodiversity are inextricably linked to their
collection methods, yet no synthesis of bias patterns or their
consequences exists. As such, views of organismal distribution and the
ecosystems they make up may be incorrect, undermining countless ecological
and evolutionary studies. Using 742 million records of 374,900 species, we
explore the global patterns and impacts of biases related to taxonomy,
accessibility, ecotype, and data type across terrestrial and marine
systems. Pervasive sampling and observation biases exist across animals,
with only 6.74% of the globe sampled, and disproportionately poor tropical
sampling. High -elevations and deep -seas are particularly unknown. Over
50% of records in most groups account for under 2% of species, and
citizen-science only exacerbates biases. Additional data will be needed to
overcome many of these biases, but we must increasingly value data
publication to bridge this gap and better represent species’ distributions
from more distant and inaccessible areas, and provide the necessary basis
for conservation and management.