Climatic determinants of budburst seasonality in four temperate-zone tree species

Several physiological processes controlling tree phenology remain poorly understood and in particular bud dormancy. Many studies have emphasised the action of chilling temperatures in breaking dormancy. However, the effect of the preceding summer temperatures has rarely been investigated although there is some evidence that they may be involved in the settlement and intensity of dormancy as well as cold acclimation. In this paper, thermal time to budburst in relation to the duration of chilling outdoors, preceding summer temperatures and forcing temperatures was studied by outdoors experiments in seedlings of Platanus acerifolia , Vitis vinifera , Quercus pubescens and Castanea sativa . Results showed that temperatures of the preceding summer had no significant effect on the timing of budburst, P. acerifolia and Q. pubescens showed a very weak response to the duration of chilling, and the phenological characteristics of each species were found to be adapted to the climate conditions of its own geographical area. The phenological model used in this study explained 82–100% of the variance of the data without taking into account summer temperatures. Thus, although summer temperatures may be well involved in the intensity of dormancy and cold hardiness, they do not significantly affect budburst and therefore may not need to be considered in phenological models for predicting budburst.     

ISOPOD TRACKWAYS FROM THE CRAYSSAC LAGERSTÄTTE, UPPER JURASSIC, FRANCE

Abstract:  Well-preserved arthropod trackways are described from the laminated limestones of the Crayssac Lagerstätte (south-west France, Lower Tithonian). They occur in sediments deposited in the temporary coastal mudflats of intertidal to supratidal zones. The trackways are referred to Pterichnus isopodicus isp. nov., and are interpreted as the locomotion traces of isopods. Different trackway morphotypes are recognized and clearly resulted from variations in the original consistency of the sediment. Sinuous trackways may correspond to vagrant activity on wet mud whereas numerous straight ones indicate a more rapid crawling on a soft-to-firm substratum (e.g. tidal flat during emersion). The preferred orientation of trackways indicates that isopods were crawling in a direction perpendicular to shoreline as a result of possible taxis induced by sediment wetness and/or by a migratory behaviour controlled by tidal rhythm. Unusually long emergence of the sediments may have favoured the preservation of dense networks of trackways. An isopod identity is supported by the general morphology of the tracks and the association of trackways with isopod body fossils. Archaeoniscus , which occurs abundantly in Late Jurassic deposits of England and France, was probably the trace-maker.     

Multi-scale analysis of responses of stream macrobenthos to forestry activities and environmental context

1. Forestry activities can greatly modify the structure and function of invertebrate communities in streams, but the ability to detect effects of forestry may depend on the spatial scale considered, the choice of response metric and the environmental context. In this study, a multi‐scale, multi‐metric approach was used to compare the usefulness of proximate and larger‐scale measurements of forestry activity for understanding the impacts of forestry on stream macrobenthos. 2. Site‐specific responses of macrobenthic communities to forestry activities measured at four spatial scales (sub‐basin and 8‐, 2‐ and 0.5‐km radii upstream of study sites) were examined for 90 riffle sites distributed among 22 tributary streams (Strahler order 1–5) of the Cascapedia River basin, Quebec, Canada. 3. Multiple regression models and canonical correspondence analysis were used to relate six biological metrics (taxonomic richness, numerical density, biomass density, normalised biomass spectrum, individual body mass and community structure) to variables quantifying logging 1–19 years prior to the study and road density. Environmental predictors (variables quantifying local habitat or landscape features) were included in all analyses to statistically account for environmental context and increase the likelihood of detecting potentially subtle forestry impacts. 4. Forestry activities measured at the larger (sub‐basin and 8 km) scales were linked to decline in taxonomic richness, increase in numerical and biomass densities and shift in size structure of benthic macroinvertebrates, indicating that analyses encompassing larger areas, up to the full basin, may allow for more sensitive detection of effects than those of more limited span. 5. These responses primarily reflected marked increases in the abundance of chironomids and decline in the number of trichopteran taxa with increasing areal coverage of recent (≤2–4 years) cuts, suggesting that larger, longer‐lived and possibly more specialised taxa were more vulnerable to forestry impacts than smaller, multivoltine, generalist invertebrates. After partialling out the influence of other variables, rapid decline in richness occurred even when <1% of the basin had been clear cut in the year prior to the study. 6. Effects of forestry were detected after statistically accounting for natural environmental variability, which may have otherwise concealed those effects. The combined use of multiple biological metrics, partialling out of environmental effects and measurement of impacts at multiple spatial scales may be a broadly applicable approach for enhancing sensitivity and facilitating interpretation in studies of anthropogenic effects on macroinvertebrate communities.     

The Use of Protamine-Coated Slides for Immobilizing Protozoa*

Fresh-water, marine or parasitic protozoa can be immobilized for microscopic observation on protaminecoated slides. They appear not to be harmed by this procedure. The type of protamine derivative and its concentration are important, best results being obtained with 0.015–0.05% (w/v) of protamine sulfate.     

Postzygotic isolation between the two European subspecies of the house mouse: estimates from fertility patterns in wild and laboratory-bred hybrids

We assessed the fertility (reproductive success, litter size, testis weight, spermatocyte-to-spermatid ratio) of F₁s and backcrosses between different wild-derived outbred and inbred strains of two mouse subspecies, Mus musculus domesticus and M. m. musculus . A significant proportion of the F₁ females between the outbred crosses did not reproduce, suggesting that female infertility was present. As the spermatocyte-to-spermatid ratio was correlated with testis weight, the latter was used to attribute a sterile vs. fertile phenotype to all males. Segregation proportions in the backcrosses of F₁ females yielded 11 (inbred) to 17% (outbred) sterile males, suggesting the contribution of two to three major genetic factors to hybrid male sterility. Only one direction of cross between the inbred strains produced sterile F₁ males, indicating that one factor was borne by the musculus X-chromosome. No such differences were observed between reciprocal crosses in the outbred strains. The involvement of the X chromosome in male sterility thus could not be assessed, but its contribution appears likely given the limited introgression of X-linked markers through the hybrid zone between the subspecies. However, we observed no sterile phenotypes in wild males from the hybrid zone, although testis weight tended to decrease in the centre of the transect.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 84 , 379–393.     

Site prioritisation for the protection of rare subterranean species – the cases of two ostracods from south-western France

1. Delineation of protected areas for rare subterranean species is a key problem for groundwater biodiversity conservation, because of practical difficulties in implementation. Criteria for site selection are presented that are derived from studies on two remarkable Ostracoda, Dolekiella europaea Gidó, Artheau, Colin, Danielopol & Marmonier (Limnocytheridae) and Vestalenula carveli Artheau (Darwinulidae) discovered in south-western France.
2. Arguments for natural heritage value and protection of subterranean species are proposed and illustrated by using information on these two ostracod species. The proposed criteria are: (i) local and/or regional endemism; (ii) known occurrence of the species at a few localities only; (iii) representativeness for ancient phylogenetic lineages with wider geographical distributions in the past; and (iv) suitability for scientific study because of unique morphological or biological traits.
3. It is also proposed to prioritise the protection of subsurface sites using the following criteria: (i) type locality for newly described species; (ii) presence of other rare stygobiotic taxa; and (iii) high population densities of the primary target species.
4. Development and implementation of protection strategies at local scale are likely to benefit from collaboration between scientists, policy makers and stakeholders. The measures taken should complement existing national and/or international attempts at large-scale protection of groundwater biodiversity.     

Understanding Fluctuations in Bobcat Harvest at the Northern Limit of Their Range

ABSTRACT In Quebec, Canada, harvest of bobcats (Lynx rufus) started to decline in 1985 and by 1991, harvest seasons were closed due to concerns of a perceived population decline. Since the closing of harvest season in 1991, the average temperature has increased, snow quantity has decreased, and important changes in agriculture and forest management have occurred. In light of changing conditions, the situation of Quebec bobcats needed reassessment. Thus, we analyzed harvest data to clarify the current status of bobcat populations in Quebec. From 1980 to 1991, bobcat harvest in Quebec was strongly correlated with bobcat harvest in Maine (USA), Nova Scotia (Canada), Ontario (Canada), and Vermont (USA). Extrapolations of harvest in Quebec relative to harvest in Maine, Ontario, Vermont, and Nova Scotia suggested an increase in number of bobcats after 1991. Mass of male and female bobcats before 1991 was less than mass of animals captured after 1991. Percentage of juveniles in the reported harvest before 1991 was higher than after 1991. However, percentage of males and litter sizes in the harvest did not differ before and after 1991. The geographic distribution of bobcats captured has gradually expanded after the closure of the harvest season. Our findings suggest that bobcat populations in Quebec have recovered from the 1985–1991 decline, and that the harvest season for this species could resume. This study also illustrates how managers can rely on data from neighboring jurisdiction to manage species when local harvest data is unavailable.