Spider biogeography of the Americas: from literature data to diversity patterns

Abstract

Biodiversity is one of the fundamental issues in biology. The spatial variation in biodiversity results in distinct distribution patterns among different taxa. Generating and synthesizing knowledge about species distribution and diversity is one of the main challenges to understanding biodiversity variation and its factors. Distribution data are often very heterogeneous, derived from different sources and with different data standards. The discrepancy and heterogeneity of data is more evident for invertebrates, which restricts our basic knowledge about the group. In the case of spiders, one of the most diverse and ecologically relevant groups, the gap in taxonomic and biogeographic knowledge directly impacts the assessment of their diversity and distribution. This work seeks to improve this understanding by addressing issues related to the quality and availability of occurrence data, the relationship between description and publication of records, in addition to describing the distribution and diversity patterns of spiders in the Americas. The Americas are the largest portion of land with continuous latidudinal extension on the planet, encompassing a wide variety of ecoregions. Despite there is some well-studied regions, such as Brazil and the United States of America, most of the continent shows knowledge gaps. To fill the knowledge gaps on spider biodiversity in the Americas, different aspects of biodiversity were analyzed based on a database developed from academic literature, called SPIDBASE. This database allows for a more precise approach to spider diversity, based on published, publicly accessible and traceable data, allowing investigations into biogeographic and taxonomic patterns. The first chapter presents the construction of SPIDBASE, a relational database that brings together approximately 150000 records of spider occurrences from academic literature. This database arose from the need to improve the accuracy and reliability of biodiversity data, due to the constant increase in the amount of this type of information. These data, generally obtained from scientific collections and open access databases, present some challenges related to accessibility, integration and usability due to their high heterogeneity, making it difficult to implement standards and affecting the quality and reliability of the data. SPIDBASE serves as a comprehensive repository and dynamic tool for taxonomic and biogeographic research. The inclusion of the taxonomic history of each record in the database allows for the tracking of the dynamics of nomenclatural changes over time, and the implementation of the entity- relational model, combined with the use of ontologies, improves reliability and integrity so that it is an expandable and interoperable tool with other databases, improving its usability and becoming a valuable resource for research and conservation. The second chapter explores the shelf-life of species and records, concepts important for understanding taxonomic impediment. The shelf-life are the time delay between the sampling of the oldest record of any species and the publication of the same species (species shelf-life) and the sampling of any record and its publication (record shelf-life). This metric can help to understand how the productivity of biodiversity inventories is affected by taxonomic impediment and offer new insights for developing conservation strategies and prioritizing resources for taxonomic research. Using SPIDBASE data, it was possible to estimate that the spider species shelf-life is approximately 25 years, a higher value than previously estimated. This difference may be due to the sensitivity of the metric, varying with the data used. This time delay significantly impacts knowledge about the distribution of species, highlighting the importance of taxonomic research, the need for investment in basic taxonomic research, and the management of biological collections to reduce the knowledge gap. In third chapter, the diversity patterns of spiders in the Americas are described, analyzing different metrics such as record density, sampling effort, species richness, endemicity and species composition. To determine the distribution patterns, SPIDBASE was used together with softwares like ArcGIS Pro, DinamicaEGO and R, resulting in maps that show how spider diversity varies spatially in the Americas. The results indicate that large-scale spider biodiversity is strongly associated with human population density, highlighting biases in distribution data, in addition these areas also coincide with regions of high diversity already known. Specific divergences in the patterns found, particularly in the Manitoba region (Canada), emphasize the need for more research in poorly studied regions, highlighting how much our knowledge depends on the available data and how it may be underestimated. This work is an attempt to improve our understanding of the biogeography of spiders in the Americas, emphasizing the complexity of assessing diversity and the importance of considering factors, like sampling biases in poorly studied areas, to improve our knowledge of spider biodiversity. The fourth chapter addresses the patterns of distribution and diversity of spiders as a function of gradients of variation in environmental, latitudinal and altitudinal variables. The variations in diversity along these gradients are some of the most supported hypotheses for several animal and plant groups. To understand how these patterns relate to spider diversity, SPIDBASE and the biogeographic patterns found in this work were used. The results showed that the number of species is positively affected by area and scale. The latitudinal gradient patterns estimate greater diversity at latitudes closer to 0°, 20°N and 20°S. The altitudinal gradient patterns estimate greater diversity at lower altitudes. The environmental gradient patterns estimate greater diversity at warmer temperatures, low to medium precipitation and productivity, and climate stability. This study provides a comprehensive description of spider diversity patterns, contributing to a better understanding of spider diversity in the Americas. This work highlights the importance of improving the quality of biodiversity data, reducing biases associated with collection, and highlight taxonomic research as a basis for biodiversity knowledge. The implementation of SPIDBASE represents a significant advance, providing a detailed basis for taxonomic and biogeographic studies of spiders and enabling more precise analyses of diversity and distribution patterns.