GMBA network - 2016 journal articles
Plant invasions into mountains and alpine ecosystems: current status and future challenges
Alexander J, Lembrechts J, Cavieres L, Daehler C, Haider S, Kueffer C, Liu G, McDougall K, Milbau A, Pauchard A, Rew L, and Seipel T (2016), Alpine Botany, DOI 10.1007/s00035-016-0172-8
Recent years have seen a surge of interest in understanding patterns and processes of plant invasions into mountains. Here, we synthesise current knowledge about the spread of non-native plants along elevation gra- dients, emphasising the current status and impacts that these species have in alpine ecosystems. Globally, inva- sions along elevation gradients are influenced by propagule availability, environmental constraints on population growth, evolutionary change and biotic interactions. The highest elevations are so far relatively free from non-native plants. Nonetheless, in total nearly 200 non-native plant species have been recorded from alpine environments around the world. However, we identified only three species as specifically cold-adapted, with the overwhelm- ing majority having their centres of distribution under warmer environments, and few have substantial impacts on native communities. A combination of low propagule availability and low invasibility likely explain why alpine environments host few non-native plants relative to low- land ecosystems. However, experiences in some areas demonstrate that alpine ecosystems are not inherently resistant to invasions. Furthermore, they will face increasing pressure from the introduction of pre-adapted species, climate change, and the range expansion of native species, which are already causing concern in some areas. Nonetheless, because they are still relatively free from non- native plants, preventative action could be an effective way to limit future impacts of invasions in alpine environments.
Distributional shifts – not geographic isolation – as a probable driver of montane species divergence
Lacey Knowles L and Massatti R (2016), Ecography, DOI 10.1111/ecog.02893
As biodiversity hotspots, montane regions have been a focus of research to understand the divergence process. Like their oceanic counterparts, the diversity of the ‘sky islands’ might be ascribed to geographic isolation of mountaintops. However, because the sky islands, and especially those in northern latitudes, are subject to extreme climatic events such as the glacial cycles that drove both altitudinal and geographical shifts in species’ distributions, the dynamic colonization process is also a possible factor driving divergence. Here we test these two hypotheses (i.e. isolation versus colonization) in a flightless montane grasshopper, Melanoplus oregonensis, which is a member of a diverse group that radiated across the Rocky Mountains of North America. Using approximate Bayesian computation (ABC) and spatially explicit simulations that account for spatial heterogeneity and temporal shifts in species distributions, we show that a colonization model of the sky islands from refugial populations provides a significantly better fit to the empirical genetic data than a model of the geographic isolation among sky islands. Moreover, support for the colonization model holds irrespective of whether the movement of individuals was modeled as a diffusion process or was informed by differences in habitat suitabilities across the landscape. With validation analyses to confirm the models provide a good fit to the data, as well as general power and quality analyses, the research not only adds to a growing body of work on the complex dynamics underlying montane biodiversity, but it also provides much needed evaluation of competing hypotheses based on explicit models of the divergence process, as opposed to inferences about diversification drivers from species diversity patterns.
Non-native and native organisms moving into high elevation and high latitude ecosystems in an era of climate change: new challenges for ecology and conservation
Pauchard A, Milbau A, Albihn A, Alexander J, Burgess T, Daehler C, Englund G, Essl F, Evengard B, Greenwood G, Haider S, Lenoir J, McDougall K, Muths E, Nunez M, Olofsson J, Pellissier L, Rabitsch W, Rew L, Robertson M, Sanders N, and Kueffer C (2016), Biological Invasions, DOI 10.1007/s10530-015-1025-x
Cold environments at high elevation and high latitude are often viewed as resistant to biological invasions. However, climate warming, land use change and associated increased connectivity all increase the risk of biological invasions in these environments. Here we present a summary of the key discussions of the workshop ‘Biosecurity in Mountains and Northern Ecosystems: Current Status and Future Challenges’ (Flen, Sweden, 1–3 June 2015). The aims of the workshop were to (1) increase awareness about the growing importance of species expansion—both non-native and native—at high elevation and high latitude with climate change, (2) review existing knowledge about invasion risks in these areas, and (3) encourage more research on how species will move and interact in cold environments, the consequences for biodiversity, and animal and human health and wellbeing. The diversity of potential and actual invaders reported at the workshop and the likely interactions between them create major challenges for managers of cold environments. However, since these cold environments have experienced fewer invasions when compared with many warmer, more populated environments, prevention has a real chance of success, especially if it is coupled with prioritisation schemes for targeting invaders likely to have greatest impact. Communication and co-operation between cold environment regions will facilitate rapid response, and maximise the use of limited research and management resources.
Integrating genetic and stable isotope analyses to infer the population structure of the White-winged Snowfinch Montifringilla nivalis in Western Europe
Resano-Mayor J, Fernández-Martín Á, Hernández-Gómez S, Toranzo I, España A, Gil JA, de Gabriel M, Roa-Álvarez I, Strinella E, Hobson KA, Heckel G, and Arlettaz R (2016), Journal of Ornithology, DOI 10.1007/s10336-016-1413-8
The population structure and seasonal movements of alpine birds in Europe are still largely unknown. Species living in high mountains now face acute risks of habitat loss, range contractions and local extinction due to current and projected climate change. Therefore, a better understanding of the spatial structuring and exchange among populations of European mountain birds is important from both ecological and conservation points of view. The White-winged Snowfinch Montifringilla nivalis is one of the most characteristic passerines of alpine habitats in Europe. Despite the fact that its breeding nuclei are relatively well defined, we still know little about the species’ population structure and movements in Western Europe. By analysing two mitochondrial loci (cytochrome b and the control region) and stable isotopes of hydrogen (δ2H), we assessed to what extent breeding populations of Whitewinged Snowfinches in the Cantabrian Mountains (CM), the Pyrenees and the Alps, and also a wintering population in the Eastern Pyrenees, function as a metapopulation. We first show the phylogenetic relationships of the Whitewinged Snowfinch (Montifringilla nivalis subsp. nivalis) within the Snowfinch complex. When assessing the population structure in Western Europe, most mitochondrial haplotypes were present in all breeding populations, but one was only found in the CM where it predominated. The most widespread haplotypes at the breeding grounds were found in the majority of the wintering individuals, but none of them showed the haplotype specific to the CM. We did not find differences in δ2H for the primary feathers among breeding populations, but rectrices of individuals wintering in the Pyrenees had considerably lower δ2H values: isotopic analysis could thus be useful to assign wintering birds to their Alpine breeding grounds. Further studies combining ringing and the analyses of intrinsic markers are an essential step in better appraising the species’ metapopulation dynamics and guiding conservation.