The strong influence of collection bias on biodiversity knowledge shortfalls of Brazilian terrestrial biodiversity

Abstract

Aim The knowledge of biodiversity facets such as species composition, distribution and ecological niche is fundamental for the construction of biogeographic hypotheses and conservation strategies. However, the knowledge on these facets is affected by major shortfalls, which are even more pronounced in the tropics. This study aims to evaluate the effect of sampling bias and variation in collection effort on Linnean, Wallacean and Hutchinsonian shortfalls and diversity measures as species richness, endemism and beta-diversity. Location Brazil.Methods We have built a database with over 1.5 million records of arthropods, vertebrates and angiosperms of Brazil, based on specimens deposited in scientific collections and on the taxonomic literature. We used null models to test the collection bias regarding the proximity to access routes. We also tested the influence of sampling effort on diversity measures by regression models. To investigate the Wallacean shortfall, we modelled the geographic distribution of over 4000 species and compared their observed distribution with models. To quantify the Hutchinsonian shortfall, we used environmental Euclidean distance of the records to identify regions with poorly sampled environmental conditions. To estimate the Linnean shortfall, we measured the similarity of species composition between regions close to and far from access routes. Results We demonstrated that despite the differences in sampling effort, the strong collection bias affects all taxonomic groups equally, generating a pattern of spatially biased sampling effort. This collection pattern contributes greatly to the biodiversity knowledge shortfalls, which directly affects the knowledge on the distribution patterns of diversity.Main conclusions The knowledge on species richness, species composition and endemism in the Brazilian biodiversity is strongly biased spatially. Despite differences in sampling effort for each taxonomic group, roadside bias affected them equally. Species composition similarity decreased with the distance from access routes, suggesting collection surveys at sites far from roads could increase the probability of sampling new geographic records or new species.

New records of spiders (Arachnida, Araneae) from the state of Roraima, northern Brazil

“…The sampling heterogeneity in Roraima is not different from the overall situation throughout Brazil (Brescovit et al 2011: fig. 5), and corresponds to a general rule for Brazilian invertebrates, vertebrates and angiosperms (Lewinsohn et al 2005;Oliveira et al 2016). Even within the relatively betterstudied animal groups and biomes, such as the Atlantic and the Amazon Forests, geographic coverage is very restricted and often just a few localities have been sampled adequately (Lewinsohn et al 2005).…”

“…Even within the relatively betterstudied animal groups and biomes, such as the Atlantic and the Amazon Forests, geographic coverage is very restricted and often just a few localities have been sampled adequately (Lewinsohn et al 2005). As a result, there is a strong spatial bias regarding the species richness, species composition and endemism knowledge in the Brazilian biodiversity (Oliveira et al 2016).…”

“…This heterogeneous knowledge is highly influenced by where the main national research institutions, which harbor the most significant collections, and researchers on spider systematics are located. Collections are mostly composed of species gathered nearby (Brescovit et al 2011), significantly associated to access routes, creating larger knowledge shortfalls in localities far from the main research centers (Oliveira et al 2016).…”

“…For example, the Amazon has the lowest record density for invertebrates, vertebrates and angiosperms among all Brazilian biomes (Oliveira et al 2016). Regarding spiders, there is a historical concentration of sampling effort mostly in small regions (Oliveira et al 2015).…”

Comparing and contrasting threat assessments of plant species at the global and sub-global level

“…As with taxonomic bias, the geographical bias in conservation activity, including biodiversity data collection and publication has been well documented (Reddy and Dávalos 2003;Boakes et al 2010;Trimble and van Aarde 2012;Oliveira et al 2016). In general, despite high species diversity, tropical areas are understudied and underrepresented in biodiversity data (Kier et al 2005;Collen et al 2008).…”