Leveraging historical field notebooks to uncover continental-scale patterns in the diversity of Australian grasshoppers

1. An understanding of how biodiversity is distributed across the broad spatial scales can resolve pure questions about ecological and historical processes and solve applied problems in conservation planning. Invertebrates such as insects make up much of biodiversity yet are rarely a focus in studies of regional-scale diversity patterns, partly due to data deficiency. 2. We took advantage of historical field notebooks to investigate the richness and compositional pattern of grasshoppers across a vast area of Australia (Western Australia, 2.6 million km(2)). We extracted grasshopper occurrence records from historical surveys of 1328 locations spanning 1947 to 1985. We developed generalised dissimilarity models to identify species compositional turnover across families and modelled species richness with regression analyses. 3. Species composition was most distinct in mesic south-west, north and north-west regions and was most uniform through the arid interior region with the exception of the topographically complex Pilbara region. Species richness was highest in the arid interior and north and lowest in the cool and wet south-west. 4. The patterns of grasshopper species diversity and endemism were like patterns previously reported for lizards and this may reflect their common independence from water and their phylogenetic bias towards warm environments. 5. Although high species richness was predicted in the Pilbara region, the area remains underrepresented in the national reserve system, with <10% of its area protected. High levels of short-range endemism were found in general, with only similar to 1/4 of short-range endemics being located in the national reserve system. 6. Our analyses demonstrate that field notebooks can be a valuable resource for biogeographic analyses and for planning invertebrate conservation.