Estimating the impact of past persecution and habitat changes on the numbers of Badgers Meles meles in Britain

Data from a Badger sett survey undertaken in the mid-1980s were used to calculate the effects of past persecution and land-use changes on Badger numbers. The current British Badger population was estimated to be 41,894 ± 4404 social groups; if the effects of past persecution were eliminated, the population could be 43,437 ± 4731 social groups, an increase of 3.7%. Most of this increase relates to persecution in Norfolk and Suffolk last century. In Britain the Badger population is largely confined to those areas which are intensively managed, and the numbers and distribution of Badgers reflect patterns of agricultural activity. However, over-intensive use of the landscape is detrimental to Badger numbers. To quantify the impact of land-use changes on the British Badger population, a number of habitat features favourable to Badgers were identified; 1-km squares that contained five or more such features had significantly higher mean Badger densities. If all the 1-km squares were managed to include five or more of the habitat features favoured by Badgers, and the effects of persecution were eliminated, the Badger population could be 58,284 ± 5640 social groups, an increase of 39%. The absence of semi-natural broadleaved woodlands in a 1-km square had the greatest effect in reducing Badger numbers, and tree-planting schemes may be beneficial in providing potential new sett sites. However, Badgers are poor colonists, and the construction of artificial setts and the translocation of displaced social groups of Badgers will greatly facilitate the colonization process. The value of such an approach for predicting the effects of future land-use policy on Badgers and other species, and for managing the British wildlife resources, is discussed.     

Ant body posture: gaster curling increases ant speed

1. Body postures adopted by an animal can serve behavioural functions, homeostasis, or energy balance. 2. We investigated the function of holding the gaster curled forward under the thorax in acacia ants, Pseudomyrmex spinicola Emery, by testing whether ants adopted this posture for defence, thermoregulation, or for efficient locomotion. 3. For the defence hypothesis, we expected an increase in the proportion of ants with curled gasters after a visual threat, a vibrational disturbance of a branch, or the release of nestmate's alarm pheromones. Our data did not support these predictions. 4. For the thermoregulation hypothesis, we found a positive correlation between temperature and proportion of curled‐gaster ants. However, we did not find a reduction in the proportion of curled‐gaster ants after shading them, as predicted by this hypothesis. 5. Our data supported the locomotion hypothesis: curled‐gaster ants walked 1 cm s^?1 faster than ants with the gaster held straight. Straight‐gaster ants walked with the thorax closer to the surface, a posture that likely shifts the centre of gravity closer to the surface in a manner similar to gaster curling. 6. Studying the role of the body posture in acacia ants and other insects will provide a better understanding of the kinematics of walking in challenging angles with respect to gravity.     

Taxonomy and evolution of European brown frogs

Phylogenetic relationships within the Euro-Mediterranean stock of the Rana temporaria species group (R. temporaria, R. iberica, R. cameranoi, R. macrocnemis, R. holtzi, R. dalmatina, R. graeca, R. latastei) were studied by (1) morphometric analysis, (2) osteological study and (3) electrophoresis. The three data sets were analysed independently and phenograms and cladograms examined for congruent patterns. The tree resulting from electrophoretic analysis is the most clearly resolved (and being also compatible with the other two) is assumed to represent the most likely phylogeny of the Mediterranean brown frogs. Patterns indicated by electrophoretic data matched the molecular clock-hypothesis. This suggests that the first split of the main stock of Mediterranean brown frogs separated ancestors of Rana temporaria and R. iberica from the others during the Late Pleistocene. A second split occurred separating the ancestors of what are currently the other big-bodied and the small-bodied brown frogs. The relationships between and within the three main stocks are discussed in the context of biogeographical and geological data.     

Thermotropic Properties of Cellular Membranes in Dormant and Non-Dormant Echinochloa crus-galli(L.) Beauv. Seeds

Steady-state fluorescence polarization measurements with l,6-diphenyl-l,3,5-hexatriene(DPH) were used to monitor thermotropic transitions in microsomalfractions and plasma membrane vesicles isolated from barnyardgrass[Echinochloa crus-galli (L.) Beauv.] seeds during the transititionfrom dormancy to germination. The effect of dormancy-relievingor inactive alcohols on the thermotropic properties of the cellularmembranes was determined both in vivo and in vitro. Membranefractions isolated from dormant seeds showed some discontinuitiesin the Arrhenius plots. In non-dormant or germinating seedscellular membranes showed linear Arrhenius plots over the entirerange of temperature examined. Membrane preparations from imbibedseeds showed a similar pattern in their Arrhenius plots upontreatment with the various alcohols in vitro. The results suggestthat the release from dormancy in seeds is associated with somechanges in their cellular membranes. Key words: Germination, alcohols, thermotropic transition     

Physiological factors affecting the rapid decrease in protein assimilation efficiency by a caterpillar on newly‐mature tree leaves

Lymantria dispar L. caterpillars have a decreased ability to assimilate protein from mature leaves of red oak (Quercus rubra) compared with young, expanding leaves. The present study determines whether the drop in protein assimilation efficiency (PAE) occurs during the rapid phase of leaf maturation. Several mechanisms that might account for decreased PAE are also examined: mature leaf tissues could resist being chewed efficiently, protein in mature leaf tissues could become difficult to extract, and other nutrients in mature leaves might become growth limiting. The entire seasonal decrease in PAE occurs rapidly (in less than 2 weeks), when the leaves finished expanding. The maturation process is characterized by increased levels of fibre and decreased levels of water but no significant changes in the levels of protein or carbohydrates. Despite increased fibre in mature leaves, they are not chewed into larger food particles than are immature leaves. Carbohydrate assimilation efficiencies remain high on mature leaves, and signs of limiting water levels in larvae of L. dispar on mature leaves are not observed. The most important finding in the present study is the decreased extractability of protein in food particles from mature leaves, which plays a major role in explaining the rapid decrease in PAE. It is hypothesized that structural changes in cell walls during the rapid process of leaf maturation decrease protein extractability, which, in turn, greatly decreases the nutritional quality of mature oak leaves for caterpillars. The results of the present study therefore suggest a general mechanism to help explain the widely documented decrease in the nutritional quality of the mature leaves of many tree species for herbivorous insects.     

RELATIONSHIPS BETWEEN PATELLA FERRUGINEA GMELIN, 1791 AND THE OTHER TYRRHENIAN SPECIES OF PATELLA (GASTROPODA: PATELLIDAE)

The external morphology of soft parts of the rare Patella ferrugineaGmelin, 1791 is described, and its relationships with P. caerulea,P. rustica and P. ulys-siponensis are investigated on both morphologicaland electrophoretic grounds. Soft part morphology is a gooddiscriminative tool, but of little help in detecting affinities.Electrophoretic data on 19 presumptive loci suggest that P.rustica is the closest species to P. ferruginea, whereas P.caerulea and P. ulyssiponensis are clustered separately. Meanobserved heterozyg-osities arc higher in P. ferruginea and P.rustica. It is concluded that in case of subdivision of thegenus Patella L., 1758, P. ferruginea and P. rustica shouldbe placed together in the subgenus Patellastra Mon-terosato,1884. (Received 6 January 1993; accepted 23 February 1993)     

Effects of Cadmium in Stylonychia lemnae, Stylonychia notophora and Oxytricha granulifera: Isolation of a Cadmium-Binding Protein

ABSTRACT The effects of cadmium on three ciliates are reported here. Cultures of Stylonychia lemnae, Stylonychia notophora and Oxytricha granulifera were treated with different doses of Cd according to tolerance. The two species of Stylonychia are very sensitive to the metal, white O. granulifera tolerates higher doses. Adding 50 μM of Cd to the medium did not damage cells. The accumulated metal is almost totally present in the particulate fraction after day 3. Two Cd-Zn linking fractions were separated from the soluble fraction of culture treated on day 1. The first protein linking 17 μg Cd/mg showed an ultraviolet absorption spectrum similar to that of Cd-thioneins. Preliminary amino acid analyses indicated that it contained 13% cysteine. The second protein, linking 60 μg Cd/mg, was a glycoprotein. Its ultraviolet absorption spectrum and amino acid analysis showed that this binding protein was far from being a metallothionein: its cysteine content was very low and aromatic and cyclic residues were present. This Cd-linking compound seems to be unique, since it was very different both from metallothioneins and chelatins isolated by other protozoa. The protective role of these chelating proteins is discussed.