Global patterns of stream detritivore distribution: implications for biodiversity loss in changing climates
Boyero, L and Pearson, RG and Dudgeon, D and Ferreira, V and Graca, MAS and Gessner, MO and Boulton, AJ and Chauvet, E and Yule, CM and Albarino, RJ and Ramirez, A and Helson, JE and Callisto, M and Arunachalam, M and Chara, J and Figueroa, R and Mathooko, JM and Goncalves Jr, JF and Moretti, MS and Chara-Serna, AM and Davies, JN and Encalada, A and Lamothe, S and Buria, LM and Castela, J and Cornejo, A and Li, AOY and M'Erimba, C and Villanueva, VD and Del Carmen Zuniga, M and Swan, CM and Barmuta, LA, Global patterns of stream detritivore distribution: implications for biodiversity loss in changing climates, Global Ecology and Biogeography, 21, (2) pp. 134-141. ISSN 1466-822X (2012) [Refereed Article]
Aim We tested the hypothesis that shredder detritivores, a key trophic guild in stream ecosystems, are
more diverse at higher latitudes, which has important ecological implications in the face of potential
biodiversity losses that are expected as a result of climate change. We also explored the dependence of local
shredder diversity on the regional species pool across latitudes, and examined the inﬂuence of environ-
mental factors on shredder diversity.
Location World-wide (156 sites from 17 regions located in all inhabited continents at latitudes ranging
from 67° N to 41° S).
Methods We used linear regression to examine the latitudinal variation in shredder diversity at different
spatial scales: alpha (a), gamma (g) and beta (b) diversity. We also explored the effect of g-diversity on
a-diversity across latitudes with regression analysis, and the possible inﬂuence of local environmental
factors on shredder diversity with simple correlations.
Results Alpha diversity increased with latitude, while g- and b-diversity showed no clear latitudinal
pattern. Temperate sites showed a linear relationship between g- and a-diversity; in contrast, tropical sites
showed evidence of local species saturation, which may explain why the latitudinal gradient in a-diversity
is not accompanied by a gradient in g-diversity. Alpha diversity was related to several local habitat
characteristics, but g- and b-diversity were not related to any of the environmental factors measured.
Main conclusions Our results indicate that global patterns of shredder diversity are complex and
depend on spatial scale. However, we can draw several conclusions that have important ecological
implications. Alpha diversity is limited at tropical sites by local factors, implying a higher risk of loss of key
species or the whole shredder guild (the latter implying the loss of trophic diversity). Even if regional
species pools are not particularly species poor in the tropics, colonization from adjacent sites may be
limited. Moreover, many shredder species belong to cool-adapted taxa that may be close to their thermal
maxima in the tropics, which makes them more vulnerable to climate warming. Our results suggest that
tropical streams require speciﬁc scientiﬁc attention and conservation efforts to prevent loss of shredder
biodiversity and serious alteration of ecosystem processes.