TY  - JOUR
A1  - Gros, Andreas
A1  - Poethke, Hans Joachim
A1  - Hovestadt, Thomas
T1  - Sex-specific spatio-temporal variability in reproductive success promotes the evolution of sex-biased dispersal
N2  - Abstract: Inbreeding depression, asymmetries in costs or benefits of dispersal, and the mating system have been identified as potential factors underlying the evolution of sex-biased dispersal. We use individual-based simulations to explore how the mating system and demographic stochasticity influence the evolution of sex-specific dispersal in a metapopulation with females competing over breeding sites, and males over mating opportunities. Comparison of simulation results for random mating with those for a harem system (locally, a single male sires all offspring) reveal that even extreme variance in local male reproductive success (extreme male competition) does not induce male-biased dispersal. The latter evolves if the between-parch variance in reproductive success is larger for males than females. This can emerge due to demographic stochasticity if the habitat patches are small. More generally, members of a group of individuals experiencing higher spatio-temporal variance in fitness expectations may evolve to disperse with greater probability than others.
KW  - sex-biased dispersal
KW  - demographic stochasticity
KW  - metapopulation
KW  - individual-based simulation
KW  - sex-specific competition
Y1  - 2009
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-48711
ER  - 
TY  - JOUR
A1  - Heisswolf, Annette
A1  - Reichmann, Stefanie
A1  - Poethke, Hans-Joachim
A1  - Schröder, Boris
A1  - Obermaier, Elisabeth
T1  - Habitat quality matters for the distribution of an endangered leaf beetle and its egg parasitoid in a fragmented landscape
N2  - Fragmentation, deterioration, and loss of habitat patches threaten the survival of many insect species. Depending on their trophic level, species may be differently affected by these factors. However, studies investigating more than one trophic level on a landscape scale are still rare. In the present study we analyzed the effects of habitat size, isolation, and quality for the occurrence and population density of the endangered leaf beetle Cassida canaliculata Laich. (Coleoptera: Chrysomelidae) and its egg parasitoid, the hymenopteran wasp Foersterella reptans Nees (Hymenoptera: Tetracampidae). C. canaliculata is strictly monophagous on meadow sage (Salvia pratensis), while F. reptans can also parasitize other hosts. Both size and isolation of habitat patches strongly determined the occurrence of the beetle. However, population density increased to a much greater extent with increasing host plant density ( = habitat quality) than with habitat size. The occurrence probability of the egg parasitoid increased with increasing population density of C. canaliculata. In conclusion, although maintaining large, well-connected patches with high host plant density is surely the major conservation goal for the specialized herbivore C. canaliculata, also small patches with high host plant densities can support viable populations and should thus be conserved. The less specialized parasitoid F. reptans is more likely to be found on patches with high beetle density, while patch size and isolation seem to be less important.
KW  - Fragmentierung
KW  - Pflanzenfressende Insekten
KW  - Eiparasitismus
KW  - Metapopulation
KW  - Habitat fragmentation
KW  - herbivore
KW  - host plant density
KW  - metapopulation
KW  - multitrophic
Y1  - 2009
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-47740
ER  -