TY  - JOUR
A1  - Filip, Joanna
A1  - Bauer, Barbara
A1  - Hillebrand, Helmut
A1  - Beniermann, Anna
A1  - Gaedke, Ursula
A1  - Moorthi, Stefanie D.
T1  - Multitrophic diversity effects depend on consumer specialization and species-specific growth and grazing rates
JF  - Oikos
N2  - Ecosystem functioning is affected by horizontal (within trophic groups) and vertical (across trophic levels) biodiversity. Theory predicts that the effects of vertical biodiversity depend on consumer specialization. In a microcosm experiment, we investigated ciliate consumer diversity and specialization effects on algal prey biovolume, evenness and composition, and on ciliate biovolume production. The experimental data was complemented by a process-based model further analyzing the ecological mechanisms behind the observed diversity effects. Overall, increasing consumer diversity had no significant effect on prey biovolume or evenness. However, consumer specialization affected the prey community. Specialist consumers showed a stronger negative impact on prey biovolume and evenness than generalists. The model confirmed that this pattern was mainly driven by a single specialist with a high per capita grazing rate, consuming the two most productive prey species. When these were suppressed, the prey assemblage became dominated by a less productive species, consequently decreasing prey biovolume and evenness. Consumer diversity increased consumer biovolume, which was stronger for generalists than for specialists and highest in mixed combinations, indicating that consumer functional diversity, i.e. more diverse feeding strategies, increased resource use efficiency. Overall, our results indicate that consumer diversity effects on prey and consumers strongly depend on species-specific growth and grazing rates, which may be at least equally important as consumer specialization in driving consumer diversity effects across trophic levels.
Y1  - 2014
U6  - https://doi.org/10.1111/oik.01219
SN  - 0030-1299
SN  - 1600-0706
VL  - 123
IS  - 8
SP  - 912
EP  - 922
PB  - Wiley-Blackwell
CY  - Hoboken
ER  -