@article{fdi:010055898,
  title = {{E}nvironmental harshness and global richness patterns in glacier-fed streams},
  author = {{J}acobsen, {D}. and {D}angles, {O}livier},
  editor = {},
  language = {{ENG}},
  abstract = {{A}im {T}o test for a possible effect of environmental harshness on large-scale latitudinal and elevational patterns in taxon richness of macrofauna in arctic and alpine glacier-fed streams. {L}ocation {S}valbard (79 degrees {N}), {I}celand (65 degrees {N}), {N}orway (62 degrees {N}), {S}witzerland and {I}taly (46 degrees {N}), {F}rance (43 degrees {N}), {N}ew {Z}ealand (43 degrees {S}) and {E}cuador (0 degrees), covering an elevational gradient from sea level to 4800 m a.s.l. {M}ethods {W}e gathered data from 63 sites along 13 streams and created an index of glacial influence (the glacial index, {GI}) as an integrative proxy for environmental harshness. {T}he explicative power of the {GI}, environmental variables, latitude and elevation on taxon richness was tested in generalized linear models. {T}axon richness along geographical gradients was analysed at standardized levels of {GI} in contour plots. {B}eta diversity and assemblage similarity was calculated at different {GI} intervals and compared with a null-model. {R}esults {O}verall, taxon richness decreased exponentially with increased {GI} (r2= 0.64), and of all included factors, {GI} had the highest explicative power. {A}t low values of {GI} we found that local taxon richness varied along the coupled gradients of latitude and elevation in a hump-shaped manner. {H}owever, this pattern disappeared at high values of {GI}, i.e. when environmental harshness increased. {B}eta diversity increased, while similarity among assemblages decreased towards high {GI} values. {M}ain conclusions {I}n our study system, the number of taxa able to cope with the harshest conditions was largely independent of the regional taxon pool, and environmental harshness constituted a fixed constraint for local richness, irrespective of latitude and elevation. {C}ontrary to expectations, we found that beta diversity was highest and similarity lowest among the harshest sites, suggesting that taxon richness was not solely driven by niche selection based on environmental tolerances, but also stochastic ecological drift, leading to dispersal-limited communities.},
  keywords = {{A}quatic macroinvertebrates ; benthic communities ; dispersal limitation ; geographical gradients ; glacial rivers ; niche selection ; large-scale ; patterns ; similarity ; taxon richness},
  booktitle = {},
  journal = {{G}lobal {E}cology and {B}iogeography},
  volume = {21},
  numero = {6},
  pages = {647--656},
  ISSN = {1466-822{X}},
  year = {2012},
  DOI = {10.1111/j.1466-8238.2011.00699.x},
  URL = {https://www.documentation.ird.fr/hor/fdi:010055898},
}