On the cover: The European adder (Viper berus) is a polymorphic species with a vast distribution, occurring from western Europe to the Russian far East. Photo credit: Niels Jansen.
On the cover: The European adder (Viper berus) is a polymorphic species with a vast distribution, occurring from western Europe to the Russian far East. Photo credit: Niels Jansen.
On the cover: Euglossa imperialis is one of the most common species of orchid bees (Tribe Euglossini) in Panama. This individual was collected in Coiba National Park, a marine - terrestrial protected area found in the Pacific side of Panama. Photo credit: Yosiat Vega-Rovira.
The changing frequency and intensity of climatic extremes due to climate change can have sudden and adverse impacts on the distribution of species. While species distribution modelling is a vital tool in ecological applications, current approaches fail to fully capture the distribution of climatic extremes, particularly of rare events with the most disruptive potential. Especially at the edges of species' ranges, where conditions are already less favourable, predictions might be inaccurate when these extremes are not well represented.
Europe.
Tree species.
We present a novel approach to integrate extreme events into species distribution models based on the generalised extreme value (GEV) distribution. This distribution, following from the extreme value theory has been established as a valuable tool in analysing climatic extremes, both in an ecological context and beyond. The approach relying on the GEV distribution is broadly applicable, readily transferable across species and relies on widely available data. We demonstrate the efficacy of our approach for 28 European tree species, illustrating its superior ability to fully capture the distribution of climatic extremes compared to state-of-the-art methods.
We found that incorporating parameters on climatic extremes derived from the GEV distribution increased model performance (AICmodel) and characterised range edges more accurately (AUCedge) compared to competing approaches. However, general AUC values were only marginally increased across the species and study period analysed. Overall, the GEV model predicted a narrower niche for the species included in this study.
Incorporating climatic extremes can impact spatial predictions of species distribution models, especially at range margins. We found that using the GEV distribution to characterise extreme variables in SDMs yields the best performance at these distribution edges. Given the importance of range edges for species conservation, a detailed inclusion of extremes in SDMs employed for those applications will help ensure robust conclusions.
Tardigrades are important members of Antarctic metazoan communities with many endemic species. Major biogeographic patterns of Antarctic fauna have been identified, in particular regarding the zonation across the Gressitt line, dividing Continental and Peninsular Antarctica. Evidences suggest that Antarctic tardigrades follow this zonation too, but this has never been rigorously tested.
Limnoterrestrial ecosystems of Antarctica.
1950 to Present.
Tardigrades.
Records of tardigrades from Antarctica were collected and their taxonomy and coordinates harmonised. Alpha and Beta diversity measures were calculated and compared across different Antarctica biogeographic areas, in particular across the Gressitt line. Analyses were repeated at different spatial scales to ensure their robustness.
Tardigrades communities are different both in terms of alpha and beta diversity across the Gressitt line. Results were consistent across the analyses at different spatial scales. Taxa richness was higher in the Antarctic Peninsula compared to the Continental Antarctica. Sampling effort had a substantial effect on the measured richness. Despite having a significant effect, Gressitt line side and biogeographic areas explained a low amount of variance.
The presence of a different Tardigrade communities composition across the Gressitt line is supported, and a geographical structure is present also at smaller scales. This geographic structuring suggests local endemisms and calls for attention to eventual effects of climate change on tardigrades communities. Faunistic data on Antarctica is still far from being exhaustive and Linnean and Wallacean biodiversity shortfalls are the two most immediate issues to be solved to have a more reliable estimation of the true Antarctic tardigrades biodiversity.
The aim of the current study is to conduct a comprehensive phylogenetic analysis of the genus Arbacia to elucidate the evolution and phylogenetic relationships among all extant species and reevaluate the presence of geographic structure within species that have wide, fragmented distributions.
Specimens of Arbacia were collected from 34 localities spanning the Atlantic and Pacific Oceans, and the Mediterranean Sea.
We obtained sequences from three mitochondrial markers (COI, 16S and the control region and adjacent tRNAs) and two nuclear markers (28S and 18S; the latter ultimately excluded from the final analyses). Phylogenetic trees were constructed using maximum likelihood and Bayesian inference approaches. A time-calibrated phylogenetic tree was inferred using a relaxed Bayesian molecular clock and three fossil calibration points.
Our analysis supports the monophyly of the genus Arbacia, including the species Arbacia nigra (previously assigned to the monotypic genus Tetrapygus). The new phylogenetic topology suggests an alternative biogeographic scenario of initial divergence between Atlantic and Pacific subclades occurring approximately 9 million years ago. The dispersal and subsequent diversification of the Pacific subclade to the southeast Pacific coincides with the onset of glacial and interglacial cycles in Patagonia. In the Atlantic subclade, the split between A. punctulata and A. lixula occurred 3.01–6.30 (median 3.74 million years ago), possibly associated with the strengthening of the Gulf Stream current connecting the western and eastern Atlantic. Our study also reveals significant genetic and phylogeographic structures within both Atlantic species, indicating ongoing differentiation processes between populations.
Our study provides valuable insights into the evolutionary history and biogeography of the genus Arbacia and highlights the complex interplay between historical climate changes and oceanic currents in shaping the distribution and diversification of echinoids in the Atlantic and Pacific Oceans.
On the cover: Andryala laevitomentosa (Asteraceae) reproduces almost exclusively by vegetative reproduction and its clones are among the oldest living individuals on Earth. Mt. Pietrosul Brostenilor, Eastern Carpathians Mountains, Romania, July 2015. Photo credit: Peter Turis.
Surveying for a species of concern ahead of proposed activities that alter its habitat is routine practice in conservation and management. Such surveys may accumulate large datasets that could further elucidate trends in abundance and distribution. However, the as-needed surveying of proposed activities may impart a sample site selection bias on the data if used for another purpose. Management of a threatened, forest-nesting seabird offered an example of this. Here we assessed how resource management planning and survey requirements can bias clearance monitoring survey data collected prior to proposed timber harvests, if those data are used for other purposes.
Oregon and Washington, USA.
Marbled Murrelet (Brachyramphus marmoratus).
To assess how timber planning and other factors influenced marbled murrelet survey location selection, we used logistic regression models to examine habitat associations of marbled murrelet survey sites (n = 9178) encompassing proposed timber harvests, and the survey stations (n = 38,923) therein, across the murrelet's inland range in Washington and Oregon, USA between 1989 and 2021. We then simulated the effect this selective sampling might have on assessments of occupancy trends.
Most habitat characteristics considered did influence where surveys were located, with distance to roads often being the strongest predictor of survey location. The strength of selection for each covariate changed over time, such that a habitat characteristic strongly influenced location selection in a year but was less influential in another year. The simulation analysis suggested that the non-random selection of survey sites could profoundly bias assessments of occupancy trends.
When using these clearance monitoring survey data– or any data–beyond their original purpose, careful consideration should be given to the scope of inference provided and analytical methods used, to ensure that observed trends are the product of biological processes and not biased by sampling artefacts.
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