Influence of adaptive evolution of cadmium tolerance on neutral and functional genetic variation in Orchesella cincta.

Adaptation to environmental toxicants, such as metals, can affect population genetic diversity, both at neutral and selectable loci. At the transcriptional level, evolution of metal tolerance is possible due to the existence of polymorphisms in the cis-regulatory sequences of stress-responsive genes such as the metallothionein gene (mt). This study investigated the influence of cadmium adaptation on genetic diversity of soil-living Orchesella cincta (Collembola) populations in neutral (microsatellites and AFLP) and in functional (mt promoter) markers.

Temperature-induced gene expression associated with different thermal reaction norms for growth rate.

Although nearly all organisms are subject to fluctuating temperature regimes in their natural habitat, little is known about the genetics underlying the response to thermal conditions, and even less about the genetic differences that cause individual variation in thermal response. Here, we aim to elucidate possible pathways involved in temperature-induced phenotypic plasticity of growth rate. Our model organism is the collembolan Orchesella cincta that occurs in a wide variety of habitats and is known to be adapted to local thermal conditions.

Single locus complementary sex determination in Hymenoptera: an "unintelligent" design?

The haplodiploid sex determining mechanism in Hymenoptera (males are haploid, females are diploid) has played an important role in the evolution of this insect order. In Hymenoptera sex is usually determined by a single locus, heterozygotes are female and hemizygotes are male. Under inbreeding, homozygous diploid and sterile males occur which form a genetic burden for a population.

Energy dynamics in a parasitoid foraging in the wild.

Although parasitoids are used widely as a biological models for understanding the evolution of animal behaviour, most studies have been constrained to the laboratory. The dearth of field studies has been compounded by the almost complete ignorance of the physiological parameters involved in foraging and dispersal, in particular of the energetic constraints imposed by resource limitation. We estimated the dynamics of carbohydrates and lipids reserves of Venturia canescens (Gravenhorst) females by releasing individuals of known nutritional status in a natural environment and recapturing them using host-containing traps.

Egg Load Evolution in Parasitoids.

Parasitic wasps lay their eggs in or on other insects. Allocation of resources to reproduction (eggs) and survival (life span) should maximize reproductive success, but stochasticity in the number of hosts encountered precludes an exact match of allocation with reproductive opportunity. We study optimal egg loads using a general model for pro-ovigenic parasitoids (which only mature eggs before adult life) and a dynamic programming model for synovigenic parasitoids (which can mature additional eggs during adult life).

Cannibalism in the red wood ant, Formica polyctena (Hymenoptera: formicidae).

(1) Wars between colonies of the red wood ant, Formica polyctena (Foerst.), are very common in the study area, a dune valley near The Hague, The Netherlands. In an extensive study Mabelis (1979) has put forward a hypothesis that explains the occurrence of wars in terms of protein supply in periods of insufficient prey availability.