Climatic adaptations in the Drosophila immigrans species group: seasonal migration and thermal tolerance

Abstract. 1. In central Japan, Drosophila curviceps Okada and Kurokawa was collected in spring and autumn but not in summer at lowlands (alt. 500–1200 m), while it was collected only in summer at highlands (1500–2000 m). Experiments on its thermal tolerance suggested that summer heat at the lowlands and winter low temperatures at the highlands were adverse to this species. It is considered that this species escapes from these extreme temperatures by undergoing seasonal migration between the lowlands and the highlands. This species had no photo-periodic diapause and bred at both lowlands and highlands.
2. D.immigrans Sturtevant was less cold-hardy but more heat-tolerant than D.curviceps. It is considered that this species is unable to overwinter outdoors at least in the study areas (i.e. alt. 500m or higher in central Japan) and its populations in these areas originate with migrants from warmer areas.
3. D.albomicans Duda, a subtropical species, was less cold-hardy but more heat-tolerant than the above two species.
4. Climatic adaptations and distributions of these species are discussed with reference to their thermal tolerance.     

Development of microsatellite markers in the grey‐crowned babbler (Pomatostomus temporalis)

The grey‐crowned babbler (Pomatostomus temporalis) is a cooperative breeding bird species in which nonbreeding helpers of both sexes care for the young of breeding individuals. To measure the genetic relatedness between breeders and their offspring and helpers, we developed nine microsatellite markers. Most of the loci were highly polymorphic. These loci will be useful in understanding the evolution and maintenance of cooperative breeding and helping behaviour in this species.     

The effect of chlorophyll content on changes of photochemical reactions in intact kidney bean leaves

Abstract. Activation spectra of photochemical reactions were measured by a flash spectrophotometer in leaves having varying chlorophyll contents at different stages of greening. The increase of chlorophyll concentration up to 30 nmol cm^-2 elevated the rates of photochemical reactions at all wavelengths of light used, and was found to be produced by an increase in the amounts of reaction centres. Further accumulation of chlorophyll up to 40 nmol cm^-2 was associated with an increase in light-harvesting chlorophyll, an improved rate of photochemical reactions around 600 nm and at 700 nm, and self-absorption and screening effects where chlorophyll absorbed maximally (400–450 nm and around 680 nm).     

Negative genetic correlation between diapause duration and fecundity after diapause in a spider mite

Abstract.  1. Recently, the costs of diapause, i.e. the reduction of fecundity after diapause, have been examined from an evolutionary perspective.
2. The evolution of this trade-off should be clarified by quantitative genetic approaches, as theoretical studies address the evolution of multiple traits. Nevertheless, previous studies on the costs of diapause have been based on phenotypic correlations or experimental manipulations, whereas the genetic background underlying this trade-off remains unclear.
3. In the present study, a half-sib breeding design was used to examine the quantitative genetic relationships between diapause duration and post-diapause fecundity in the Kanzawa spider mite Tetranychus kanzawai Kishida (Acari: Tetranychidae).
4. The heritability of diapause duration, post-diapause total fecundity, and post-diapause early fecundity were 0.37, 0.14, and 0.11 respectively. Genetic correlations between diapause duration and post-diapause total fecundity, and between diapause duration and early fecundity were both significantly negative (–0.70 and –0.90 respectively). These results suggest that the cost of prolonging diapause duration is genetically based, and that these life-history traits respond to natural selection acting on them simultaneously.     

Sexual dimorphism in Champsosaurus (Diapsida, Choristodera)

Two nearly complete specimens of Champsosaurus (Diapsida, Choristodera) with distinctive morphologies, from the Tullock Formation (Early Paleocene) of northeastern Montana, USA, were described as different species. The limb bones of C. ambulator are more robust than those of C. laramiensis, indicating that C. ambulator was more adapted for walking than C. laramiensis. The phylogenetic significance of these limb bone morphologies, however, appears questionable because similar dimorphic variations occur in a closely related genus and champsosaurs from other geologic ages and locations. Female champsosaurs may have been better adapted to a terrestrial life than males due to nesting behavior on land, resulting in variable limb bone morphologies between sexes. The observed morphologic variations are, hence, hypothesized to reflect sexual dimorphism rather than sympatry of species. The C. ambulator-shaped humeri and femora, demonstrating a terrestrial adaptation, are suggested to belong to females and C. laramiensis-shaped limb bones to males. No significant variations of humeral and femoral morphologies occur in small champsosaur specimens, suggesting an aquatic niche for juveniles like adult males.