TY  - JOUR
A1  - Ryser, Remo
A1  - Häussler, Johanna
A1  - Stark, Markus
A1  - Brose, Ulrich
A1  - Rall, Björn C.
A1  - Guill, Christian
T1  - The biggest losers: habitat isolation deconsructs complex food webs from top to bottom
JF  - Proceedings of the Royal Society of London : B, Biological sciences
N2  - Habitat fragmentation threatens global biodiversity. To date, there is only limited understanding of how the different aspects of habitat fragmentation (habitat loss, number of fragments and isolation) affect species diversity within complex ecological networks such as food webs. Here, we present a dynamic and spatially explicit food web model which integrates complex food web dynamics at the local scale and species-specific dispersal dynamics at the landscape scale, allowing us to study the interplay of local and spatial processes in metacommunities. We here explore how the number of habitat patches, i.e. the number of fragments, and an increase of habitat isolation affect the species diversity patterns of complex food webs (alpha-,beta-,gamma-, diversities). We specifically test whether there is a trophic dependency in the effect of these two factors on species diversity. In our model, habitat isolation is the main driver causing species loss and diversity decline. Our results emphasize that large-bodied consumer species at high trophic positions go extinct faster than smaller species at lower trophic levels, despite being superior dispersers that connect fragmented landscapes better. We attribute the loss of top species to a combined effect of higher biomass loss during dispersal with increasing habitat isolation in general, and the associated energy limitation in highly fragmented landscapes, preventing higher trophic levels to persist. To maintain trophic-complex and species-rich communities calls for effective conservation planning which considers the interdependence of trophic and spatial dynamics as well as the spatial context of a landscape and its energy availability.
KW  - food webs
KW  - allometry
KW  - bioenergetic model
KW  - metacommunity dynamics
KW  - dispersal mortality
KW  - landscape structure
Y1  - 2019
U6  - https://doi.org/10.1098/rspb.2019.1177
SN  - 0962-8452
SN  - 1471-2954
VL  - 286
IS  - 1908
PB  - Royal Society
CY  - London
ER  - 
TY  - JOUR
A1  - Wiesner, Kerstin R.
A1  - Loxdale, Hugh D.
A1  - Köhler, Günter
A1  - Schneider, Anja R. R.
A1  - Tiedemann, Ralph
A1  - Weisser, Wolfgang W.
T1  - Patterns of local and regional genetic structuring in the meadow grasshopper, Chorthippus parallelus (Orthoptera: Acrididae), in Central Germany revealed using microsatellite markers
JF  - Biological journal of the Linnean Society : a journal of evolution
N2  - The meadow grasshopper, Chorthippus parallelus (Zetterstedt), is common and widespread in Central Europe, with a low dispersal range per generation. A population study in Central Germany (Frankenwald and Thuringer Schiefergebirge) showed strong interpopulation differences in abundance and individual fitness. We examined genetic variability using microsatellite markers within and between 22 populations in a short-to long-distance sampling (19 populations, Frankenwald, Schiefergebirge, as well as a southern transect), and in the Erzgebirge region (three populations), with the latter aiming to check for effects as a result of historical forest cover. Of the 671 C. parallelus captured, none was macropterous (functionally winged). All populations showed a high level of expected and observed heterozygosity (mean 0.80-0.90 and 0.60-0.75, respectively), whereas there was evidence of inbreeding (F(IS) values all positive). Allelic richness for all locus-population combinations was high (mean 9.3-11.2), whereas alleles per locus ranged from 15-62. At a local level, genic and genotypic differences were significant. Pairwise F(ST) values were in the range 0.00-0.04, indicating little interpopulation genetic differentiation. Similarly, the calculated gene flow was very high, based on the respective F(ST) (19.5) and using private alleles (7.7). A Neighbour-joining tree using Nei's D(A) and principal coordinate analysis separated two populations that were collected in the Erzgebirge region. Populations from this region may have escaped the effects of the historical forest cover. The visualization of the spatial arrangement of genotypes revealed one geographical barrier to gene flow in the short-distance sampling.
KW  - adaptation
KW  - gene flow
KW  - diversity
KW  - landscape structure
KW  - wing polyphenism
Y1  - 2011
U6  - https://doi.org/10.1111/j.1095-8312.2011.01698.x
SN  - 0024-4066
VL  - 103
IS  - 4
SP  - 875
EP  - 890
PB  - Wiley-Blackwell
CY  - Malden
ER  -