摘要:

The millipedeOmmatoiulus moreleti(Lucas), (Julidae) originates in the south‐west Iberian Peninsula, and has successfully invaded parts of southern Australia with hot, dry summers. The species is inactive in the field during summer but is active in autumn, particularly following rains, and in spring. There is some activity in winter. In this paper, the temperature and humidity determinants of seasonal behaviour are analysed, in particular the conditions causing summer quiescence.Experiments using a millipede treadmill apparatus at different temperatures at 95% RH showed an almost linear response of locomotor activity with temperature between 3 and 21°C, but when the temperature was increased to 28°C, the millipedes became quiescent. Activity could he restored by reducing the temperature.When the millipedes were exposed to 45% RH there was comparatively little activity at any temperature. Field evidence indicates ii rapid breaking of quiescence with surface moistureThe success ofO. moreletiin invading the surface‐litter habitat in South Australia can he explained by its ability to avoid desiccation; its adaptations include its quiescent behaviour during summer and its ability to moult from a winter (reproductive) to B summer (non‐reproductiv

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb01935.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Growth, body condition and demography of a sample of 125 banteng,Bos javanicus, from a largely unharvested wild herd on Cobourg Peninsula in northern Australia were examined. Growth (measured as changes in age‐specific head‐length) was sexually dimorphic, males growing faster and attaining larger sizes than females. Females reached maximum size in three to four years, and males in five to six years. Body condition (measured by the kidney‐fat index) was low amongst juveniles, increasing into middle age. Condition of aged females showed a marked decline. Males attained sexual maturity between three and four years, females between two and four years. Fecundity declined in older females. Breeding was seasonal, mating activity peaking during October and November, with births most frequent between June and August. Mortality amongst calves was high over the first six months of life, declining rapidly amongst older animals. Comparison of demographic data with those reported for captive herds indicates that the wild banteng in this study matured later, were less fecund, and suffered a higher rate of juvenile mortality. Lower fecundity and higher juvenile mortality were associated with patterns of age‐specific body condition, suggesting that food availability was the major factor affecting demography and hence rates of change in banteng ab

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb01936.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Variation in the growth rate of long bones is a function of the number of dividing cells in the columns of the proliferation (flat) cell zone of the growth plate, the frequency with which they divide, and the size to which they grow prior to ossification. In a previous study we found that the wide variation in bone growth rates seen among species of birds was largely associated with variation in the numbers of cells in the flat cell zone. Here we have undertaken a similar study of the growth plates of mammals and have examined variation in the morphology and cell kinetics of the tibial growth plates of a variety of species. The bone growth rates tended to he lower than those observed in birds and were particularly low in the anthropoid primates. Although quite marked variation in flat cell numbers is apparent, the results suggest that variation in cell division rate may play a relatively greater role in variation in bone growth rate among mammals than it does in birds. and that the very low hone growth rates seen in the primates are due, in part, to lower rates of cell division than in other species.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb01937.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Considerable controversy exists concerning possible effects of sexually selected phenotypes via intermale competition on reproductive success. The mandrill (Mandrillus sphinx) is an extreme example of evolution by sexual selection, and hence we have studied a semi‐free‐ranging colony of mandrills in Gabon to gather information on male rank, mating success and paternity, as determined by DNA fingerprinting. Two morphological variants or adult male were identified; ‘fatted’ males, with maximum secondary sexual coloration, which occupied dominant positions in the social group, and ‘non‐fatted’ males, with muted secondary sexual adornments, smaller testes and lower plasma testosterone levels, which lived as peripheral/solitary individuals. DNA fingerprinting analyses on infants born over five successive years showed that only the two most dominant, fatted males in the group had fathered off spring. Throughout the annual mating season these males attempted to mate‐guard and copulate with females during periods of maximal sexual skin tumescence. Male rank and mating success were strongly positively related and the alpha male sired 80–100% of the resulting offspring during three consecutive years. Non‐fatted adult males and group associated subadult males engaged in infrequent, opportunistic matings and did not guard females. Loss of alpha status resulted in a fall in reproductive success, but the effect was gradual; the deposed alpha male continued to father 67% and 25% of infants born during the next two years. Thus these results of behavioural and genetic studies on mandrills demonstrate unequivocally that clear‐cut relationships exist between male secondary sexual development, social dominance, copulatory behaviour and reproductive succes

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb01938.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Predation on newt eggs (Triturus helveticusandT. alpestris) was studied in both natural (pond) and control (aquaria) conditions. Eggs were laid on artificial supports and set in a pond near Bourg‐en‐Bresse (south‐east France). Survival from segmentation to pre‐hatching stages was similar in these two species and estimated at 0·16 ± 0·07. Survival of eggs protected in a closed bag of plastic netting was significantly higher (0·79 ± 0·08), suggesting predation as the major mortality risk. Eggs ofT. alpestriswere offered to the following potential predators: newtsTriturus alpestrisandT. helveticus(males and females), adult aquatic insects (Dytiscus marginalis, Acilius suleatus. Notonecta glauca, Ranatra linearis. Ilyocoris hermanni).a snail (Lunnaea stugnalis)and a tadpole (Rana temporaria). Only the newts and water beetles were observed to cat the eggs. Females wrapped their eggs in a fold made with the support during oviposition.D. marginalisfed on wrapped eggs and those we unwrapped in the same proportion. but newts (especially females) andA. sulcatusclearly ate fewer wrapped than unwrapped eggs. These results are discussed in terms of mortality risk and antipredato

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb01939.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Duration of paternal care in the burying beetleNicrophorus orbicollisSay is highly variable. Both parents bury and defend mouse‐sized vertebrate carcasses as food resources for their offspring, but males abandon their broods several days before females. Nests defended by single female parents were taken over by aggressive conspecifics in live of nine cases, whereas only six of 16 nests defended by both parents were taken over. In the event of a takeover, the intruding beetle replaced the resident beetle of the same sex, destroyed any eggs that were present, and paired with the remaining resident to produce a new clutch. Broods raised by usurpers following takeovers were less successful than broods raised by initial residents on unused carcasses. The majority of takeovers occurred 35 days after carcass burial. The occurrence of nest intrusions by conspecifics did not significantly influence duration of male parental care; when conspecific intruders were excluded from nests males remained with their broods (± S.E.) 11·2 ± 0·8 days (n= 15), and when intruders were added to nests males remained with their broods 12·2 ± 0·6 days (n= 8). Conflict for carcasses intensified in response to larger brood mass, but duration of male care was unaffected by brood mass. Overall. brood mass and the presence or absence of intruders explained only 5% of the variance associated with brood abandonment

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb01940.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

In the present analysis experimental results and computer modelling have been used to compare biomechanics of the two most contrasting lantern types among regular echinoids, i.e. the cidarid‐type(Stylocidaris affinis)and the camarodont(Paracentrotus lividus)lantern. The lantern is modelled as a rigid pyramid anchored in the centre of the peristomial area. Each side is connected to the test by means of muscles (protractors and retractors) rind ligaments (compass depressors). The overall movement of the lantern may be resolved into vertical displacement and lateral tilting. Computer‐aided mechanical analysis of the system takes into account the action of protractor and/or retractor muscles, their elastic reaction and the interaction with the ligamentous structures (peristomial membrane and compass depressors). The geometrical parameters have been determined by preliminary structural analysis and the values of active and passive forces have been measured experimentally. The results of simulations highlight important differences in the mechanics of theStylocidarislantern compared to that ofParacentrotus:(1) a very much greater antagonistic effect of muscular passive stretch resistance on lateral tilting: (2) a minor role of the peristomial membrane tensile strength and muscular activity in controlling vertical lantern displacement: (3) a less efficient lantern retraction and protraction owing to unfavourable muscle insertion position on the perignathic girdle and ineffective muscular contraction forces. As a conclusion, inStylocidaristhe action of the protractor and retractor muscles seems to play no significant role in moving the overall lantern, their action being mainly exerted to stabilize it. On the contrary, inParacentrotussuch stabilizing action is provided by the compass depressor ligaments. Finally, on theoretical grounds the arrangement of muscle attachments around the perignathic girdle inStylocidarisseems to be just as good as that ofParacentrotusfor controlling overall lantern mobility, if relative heights of insertions are igno

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb01941.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The histological renal anatomy of 10 species of honeyeaters was examined quantitatively, using stereology. The kidneys of five species of predominantly wet zone inhabiting birds: the western spinebillAcanthorhynchus superciliosus, White‐checked honeyeaterPhylidonyris nigra. New Holland honeyeaterPhylidonyris novaehollandiae, little wattlebirdanthochaera chrysopteraand red wattlebirdAnthochaera carunculata, were compared to five predominantly arid zone inhabiting birds: the grey‐fronted honeyeaterMeliphaga plumula, white‐plumed honeyeaterMeliphaga penicillata, white‐fronted honeyeaterPhylidonyris albifrons, spiny‐checked honeyeaterAcanthogenys rufogularisand yellow‐throated minerManorina flarigula.The kidneys were asymmetrical, with the left kidney being larger than the right kidney. Kidney mass was directly proportional to body mass (coefficient of correlation, r =+0·95), as was kidney volume to kidney mass (r =+1·0). Wet zone honeyeaters generally and a higher percentage and absolute volume of renal cortex, whilst arid zone honeyeaters generally had a significantly higher percentage and absolute volume of renal medulla. There were few differences between species, in either the percentage or absolute volume or luminal surface area of nephron components within the cortex. Within the medulla, wet zone honeyeaters generally had a higher percentage and absolute luminal surface area of collecting ducts, whilst arid zone honeyeaters had a higher percentage and absolute surface area of capillaries. This may be due to factors such as variations in diet and climate between habitats resulting in differences in honeyeater renal morphology which enable arid zone birds to conserve water and wet zone birds to conserve ions mor

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb01942.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Experimental studies of the physiological mechanisms underlying avian migration have concentrated on small passerines. The present study is concerned with the regulation of migratory fat deposition in a galliform. the European quail(Coturnix coturnix).The increased mass associated with migration was due exclusively to the deposition of fat whereas the increased body mass of laying females was due to increases in lean tissue and water as well as fat. Annual cycles of body mass, moult, gonadal size and plasma luteinizing hormone were measured every other week in captive males and females held outdoors under natural daylengths and temperatures in Bristol, UK (51° 27′ N). Males and females showed two peaks of fat deposition each year which occurred at the migratory passage times reported in wild birds. Luteinizing hormone levels and gonadal size increased in parallel with vernal fat deposition, and remained high until late summer. The pattern of primary feather moult in the intact birds was similar to that of wild quail, with moult following gonadal regression and being suspended during autumnal fattening. Castration of European quail did not inhibit the expression of migratory fattening, as it does In certain passerines. In fact, castrates displayed fattening cycles that were more clearly defined and of greater amplitude than those in the intact males. The annual cycle of European quail differs from that of other well‐studied passerine migrants such asZonotrichiasparrows, and this is most likely associated with differences in breeding ecology. In addition, the ability of quail to express vernal fattening independently of the presence of the gonads suggests that taxonomic differences between migratory species are also apparent in the physiological mechanisms of migratory fatte

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb01943.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb01945.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY