Offspring performance in dynamic habitats: key factors for a riparian carabid beetle

Abstract.  1. Knowledge of the ecology of carabid species is largely restricted to adults, although larval mortality is assumed to be the key factor in overall mortality. As low-mobility larvae are unable to avoid unfavourable conditions, habitat selection of reproducing adults should be clearly affected by the habitat factors which determine offspring performance.
2. The present study examines the key habitat factors governing the distribution patterns of Bembidion velox larvae and adults on the river banks of the River Elbe by means of habitat suitability models. The validity of the determined habitat factors for offspring performance and survival was tested in laboratory experiments.
3. In the field, B. velox adults as well as larvae show a strong association with semi-terrestrial, sandy, open soil habitats.
4. In the laboratory, overall mortality of larvae reared in different substrates was lowest in sand of medium grain size mixed with fine and coarse sand. The first larval instars in particular reacted sensitively to variations in grain size. Furthermore, flood resistance of eggs was demonstrated, as 90% of larvae hatched under permanently flooded conditions.
5. Short development times were recorded, with 4–7 days for hatching of young larvae from eggs after oviposition and approximately 28 days for the development of adults from newly hatched larvae. This probably increases the survival probability for the pre-imaginal stages in dynamic habitats.
6. In conclusion, it can be said that reproductive success is strongly dependent on oviposition site selection by adults as this reflects the ecological demands of the immature stages.     

Leaf‐cutting ants as ecosystem engineers: topsoil and litter perturbations around Atta cephalotes nests reduce nutrient availability

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A pooling approach to detect signatures of selective sweeps in genome scans using microsatellites

We have evaluated a pooling approach that can reduce the number of polymerase chain reactions in a screen for selective sweeps by more than an order of magnitude. We show that the complex peak pattern that results from pooling of all samples from a given population is a faithful reflection of the composite pattern of the individual alleles, although with an under‐representation of the larger alleles. Candidate loci for selective sweeps can be identified by visual inspection of the pool patterns. We have also implemented a software tool, which can find suitable microsatellite loci in the vicinity of annotated genes.     

Microsatellite variability in wild populations of the house mouse is not influenced by differences in chromosomal recombination rates

Differences in recombination rates along the chromosomes can influence the evolution of neutral loci via hitchhiking effects. Generally, these effects should be stronger in regions of low recombination than in regions of high recombination. Detailed information on physical and genetic maps in the house mouse now allows an assessment of the correlation between neutral variability and recombination rates at given chromosomal regions. We chose 29 microsatellite loci from chromosomal regions which show differences in recombination rates and tested their variability in samples from five wild populations of Mus musculus musculus and M. m. domesticus . Our results provide no evidence for a correlation between microsatellite variability and recombination rates. This suggests that the high average mutation rate of microsatellites in mammals counterbalances the effects of long-range hitchhiking in the mouse genome.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 84 , 629–635.