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Climate change and alpine-adapted insects: modelling environmental envelopes of a grasshopper radiation

Citation

Koot, Emily; Morgan-Richards, Mary; Trewick, Steven (2022), Climate change and alpine-adapted insects: modelling environmental envelopes of a grasshopper radiation, Dryad, Dataset, https://doi.org/10.5061/dryad.jm63xsjcs

Abstract

Mountains create steep environmental gradients that are sensitive barometers of climate change. We modelled the environmental envelopes of twelve predominantly alpine, flightless grasshopper species in Aotearoa New Zealand, using current conditions and two future global climate change scenarios: representative concentration pathway (RCP) 2.6 (1.0 °C raise) and RCP8.5 (3.7 °C raise). Two thirds of our models suggested a reduced potential range across species by 2070, but surprisingly, for six species we predict an increase in potential suitable habitat under mild (+1.0°C) or severe global warming (+3.7°C). However, when we consider the limited dispersal ability of these grasshoppers, all twelve species studied are predicted to suffer extreme reductions in range, with a quarter likely to go extinct due to a 96-100% reduction in suitable habitat. Alpine species are particularly vulnerable to the impacts of climatic shifts, and species that have limited migratory ability will be particularly at risk of habitat loss, fragmentation and local extinction. Here we present the predicted outcomes for an endemic radiation of alpine taxa as an exemplar of the challenges that alpine species, both in New Zealand, and internationally, will face in light of anthropogenic climate change

Methods

Collection of species location records

For 12 grasshopper species location records were collated from insect collections, journal articles, theses, books and Crown Pastoral Lease Tenure Reviews (Supplementary material 1) published between 1967 and 2016. These 12 endemic New Zealand grasshoppers consist of ten high elevation species: Alpinacris crassicauda, Alpinacris tumidicauda, Brachaspis collinus, Brachaspis nivalis, Paprides dugdali, Paprides nitidus, Sigaus australis, Sigaus campestris, Sigaus piliferus, and Sigaus villosus, and two low elevation relatives: Sigaus childi and Sigaus minutus. Given the range of sources used to obtain location data our sample does not suffer from the common bias of only collecting from sites close to access roads. In particular, our location data benefit from the use of Crown Pastoral Lease Tenure Reviews (CPLTR) that are produced by Land Information New Zealand (LINZ) and contain conservation reports and ecological surveys carried out by the Department of Conservation on pastures throughout Te Waipounamu (South Island) New Zealand. Additional records were retrieved from our specimen collections at Massey University. World Geodetic System 1984 (WGS84) coordinates (latitudes and longitudes) were obtained for each location record using NZ Topo Map. Location records for two additional endemic lowland grasshopper species (Phaulacridium marginale and Phaulacridium otagoense) were included in the dataset, but not modelled in this study. Both of these species have low elevation distributions and provided additional location searches and absence data that increase the accuracy of the ENMs. Coordinates were reduced to two decimal places and duplicate records within species were removed, in order to ensure only one record per ~ 1km 2 for each species. Coordinates were also mapped for each species to ensure there were no outliers due to incorrect species identification. Following filtering, a total of 949 location records were available for our analysis (manuscript fig. 1). All location records and their sources can be found in Supplementary material 1 (of the manuscript).