Diversity and Distribution of Spiders in Cusco, Peru: A Survey and Comparison of the Yale-Peruvian Expedition of 1911

Estimating the diversity of species is critical for setting conservation goals as they provide evidence regarding the impact of human activity and climate change. The Andes in South America are one of the most biologically diverse regions on Earth; however, most species inhabiting this area are unknown to science. In 1911, Yale University surveyed spiders in the Andes of Cusco-Peru and discovered 70 new species. In collaboration with Universidad Nacional San Antonio Abad del Cusco, we replicated the Yale-Peruvian expedition, following a century of land use change. Our goal was to estimate the diversity and distribution of spiders and compare our findings to the Yale expedition. Following the biodiversity-productivity hypothesis which states that productive habitats enhance arthropod communities, we hypothesized that spider communities will be more diverse in the Tropical altitudinal zone (<2000 m) than in the Highlands (>2000 m). In 2017-2018, we sampled spiders in the locations visited by Yale using plastic cups and hand-collecting techniques. A total of 1091 specimens were sampled. We identified 40 spider families and 140 species, compared to 29 families and 90 species reported in 1911. In the last 100 years, the diversity of spiders in the Tropical altitudinal zone did not vary; however, spider diversity doubled in the Highlands from 38 to 78 species, suggesting potential environmental changes in the last century. Our work serves as a foundation study to future biodiversity assessments and will be used to better understand how spider communities have responded to environmental changes in the Peruvian Andes.