The consequences of heatwaves for the reproductive success and physiology of the wingless sub-Antarctic fly Anatalanta aptera.

Sub-lethal effects of warming temperatures are an important, yet sometimes overlooked impact of climate change that may threaten the long-term survival of numerous species. This, like many other effects of climate change, is especially concerning for cold-adapted ectotherms living in rapidly warming polar regions. This study examines the effects of warmer temperatures on cold-adapted Diptera, using the long-lived sub-Antarctic sphaerocerid fly, Anatalanta aptera, as a focal species. We conducted two experiments to assess heat stress in adult flies, one varying the intensity of the heat stress (daily heating from 4 °C to 8 °C, 20 °C, or 24 °C) and one varying the frequency of heat stress exposure (heating from 4 °C to 12 °C every one, two, or three days) and examined consequences for reproductive success and metabolic responses. We found that more heat stress reduced reproductive output, but not timing of reproduction. Surprisingly, individuals sampled at different times during heat stress exposure were undifferentiable when all metabolite concentrations were analysed with redundancy analysis, however some individual metabolites did exhibit significant differences. Overall, our findings suggest that warmer temperatures in the sub-Antarctic may put this species at greater risk, especially when combined with other concurrent threats from biological invasions.

Long-term changes in herbivore community and vegetation impact of wild and domestic herbivores across Iceland.

Changes in wild and domestic herbivore populations significantly impact extensive grazing systems, particularly in low productive environments, where increasing wild herbivore populations are perceived as a threat to farming. To assess the magnitude of these changes in Iceland, we compiled time series on herbivore populations from 1986 to 2020 and estimated changes in species densities, metabolic biomass, and consumption of plant biomass in improved lands and unimproved rangelands. We compared estimates of consumption rates to past and present net primary production. Overall, the herbivore community composition shifted from livestock to wildlife dominated. However, wild herbivores only contributed a small fraction (14%) of the total herbivore metabolic biomass and consumption (4-7%), and livestock dominated the overall herbivore biomass. These insights highlight the necessity of developing improved local integrated management for both wild and domestic herbivores where they coexist.

Herbivore species coexistence in changing rangeland ecosystems: First high resolution national open-source and open-access ensemble models for Iceland.

Rangeland ecosystems are changing worldwide with the abandonment of extensive pastoralism practices and greater interest for species coexistence. However, the lack of compiled data on current changes in the abundance and distribution of herbivores challenges rangeland management decisions. Here we gathered and made available for the first time the most extensive set of occurrence data for rangeland herbivores in Iceland in an Open Access framework for transparent and repeatable science-based decisions. We mapped fine scale species distribution overlap to identify areas at risk for wildlife-livestock conflict and overgrazing. Nationwide and long term (1861-2021) occurrence data from 8 independent datasets were used alongside 11 predictor raster layers ("Big Data") to data mine and map the distribution of the domestic sheep (Ovis aries), feral reindeer (Rangifer tarandus tarandus), pink-footed geese (Anser brachyrhynchus), and rock ptarmigan (Lagopus muta islandorum) over the country during the summer. Using algorithms of Maxent in R, RandomForest, TreeNet (stochastic gradient boosting) and MARS (Splines) in Minitab-SPM 8.3, we computed 1 km pixel predictions from machine learning-based ensemble models. Our high-resolution models were tested with alternative datasets, and Area Under the Curve (AUC) values that indicated good (reindeer: 0.8817 and rock ptarmigan: 0.8844) to high model accuracy (sheep: 0.9708 and pink-footed goose: 0.9143). Whenever possible, source data and models are made available online and described with ISO-compliant metadata. Our results illustrate that sheep and pink-footed geese have the greatest overlap in distribution with potential implication for wildlife-livestock conflicts and continued ecosystem degradation even under diminishing livestock abundance at higher elevation. These nationwide models and data are a global asset and a first step in making available the best data for science-based sustainable decision-making about national herbivores affecting species coexistence and environmental management.