Study on Chemosensitive Hairs in Wolf Spiders (Araneae, Lycosidae) by Scanning Electron Microscopy

The occurrence of chemosensitive hairs in some lycosid species is examined. The distribution and shape of such hairs dorsally on the male subadult palpal tarsus and the cymbium are compared. In certain species (e.g. of the genera. Pardosa and Alopecosa) the cymbium has a dense covering of these hairs while there are rather few of these in the male subadult palpal tarsus. The cymbium of Aulonia atbimana has comparatively few chemosensitive hairs dorsally, a condition supposedly related to the web-building habit in this species. Indications are given that the cymbial chemosensitive hairs are involved in the detection of presumed contact sex pheromones produced by the female. Certain intergeneric differences in the shape of the apical part of the cymbial chemosensitive hairs are noted.     

The basic defect in cystic fibrosis.

Recent evidence strongly suggests that the cystic fibrosis gene product (CFTR) is a Cl- channel. Its properties, however, differ from those of a 30-50 pS outwardly rectifying channel previously implicated as defective in cystic fibrosis. It is still uncertain whether the pleiotropic effects of the CF defect, such as increased airway Na+ absorption and mucus sulfation, are secondary to reduced Cl- conductance, or reflect additional functions of CFTR.     

Features of the underwater light climate just below the surface in some New Zealand inland waters

1. Using sampling rates of 8–64 Hz we found clear indications of extensive and high frequency fluctuations of underwater photosynthetically active radiation (PAR) just below the surface (0.016–1.1 m) in some New Zealand water bodies. High variability and flashing occurred down to at least 3 m depth.
2. PAR variability increased under the influence of bright sunshine if wind roughening of the surface took place. Concomitantly, the average PAR levels declined by about 10%. However, even when the surface was shaded, high variability of PAR persisted.
3. Under a calm surface, PAR irradiance followed a log normal distribution. This occurred independently of the presence of direct sunlight. However, when the surface was roughened by wind in sunshine, PAR immediately switched to a Gumbel (extreme value type EV1) distribution.
4. Neither wave action nor wave focusing of incident irradiance would explain the wide range of PAR close to the water surface, although both factors add to the PAR variability.
5. The data indicate that transmittance through the surface is highly variable at the temporal and spatial scales studied, and that the irregularity of the air–water interface is instrumental in bringing about the observed fluctuations of PAR just below the surface.     

Colonization in metapopulations: a review of theory and observations

In metapopulation dynamics turnover of populations in isolated patches may be frequent. Regional survival of a species in such a system with frequent extinctions hinges on its colonization ability. Colonization is more than just dispersal; when a propagule reaches a new patch it faces higher extinction probabilities than does an established population. Extinction models as well as empirical data suggest that a large propagule with a potential for rapid increase in a varying environment, or with a low mortality rate in an environment perceived as constant, has a higher probability of successful colonization. Large variation in population size when it is still small increases the risk of failure. Factors introducing such variation are demographic stochasticity and environmental variation. It is hard to single out demographic traits that ensure good colonizing ability, since colonization can be achieved in many different ways, but generalists and species with self-fertilization seem to be superior.