摘要:

Stomach contents were examined from guillemotsUria aalge(Pont.), RazorbillsAlca torda Linnaeusand Little auksAlle alle(Linnaeus) killed by oil in the Skagerrak in January 1981. The range of prey species was small; the commonest fish found in the stomachs wereGobiusculus flavescens(Fabricius),Crystallogobius linearis(Düben),Sprattus sprattus(L.),Trisopterus minutus(L.) andAmmodytessp. The relative importance of these fish depended on bird species and locality. Guillemots contained gadoids more frequently and sandeels less frequently than razorbills, and the composition of guillemot samples from Oslo Fjord differed from that of samples from Sweden. Invertebrate remains were uncommon in all bird species; the commonest items recorded were polychaete jaws. The frequency of occurrence of items in the diet of guillemots from Oslo Fjord was apparently influenced by the extent of oiling suffered by the birds

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb04257.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Using tooth number in Green geckos from the Seychelles it is shown that growth influences can perturb an analysis of geographic variation in two ways. First, the pervasive influence of growth results in a high within‐group correlation between characters as each character is repeatedly measuring similar aspects of the phenotype. Second, there can be a bias in the growth stage of the sample such that one population is represented mainly by juveniles whilst another is represented mainly by adults. The former source of perturbation (correlation) is shown to be more influential than the latter (bias). Growth is negated, either by bivariate regression using the pooled‐within group slope, or by multiple‐group principal component analysis. The relative advantages of these procedures is discussed but in practice they gave extremely similar results. When growth is negated in this way the choice of final ordination technique is unimportant. When growth is not negated then the choice of technique is extremely important. Techniques that take account of the within‐group covariance (canonical variates) give results that are similar to the growth‐free analyses even when growth is not negated. Several facets of morphometrics such as logarithmic transformation, assessing the contribution of characters and pooling irrespective of group are critically

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb04258.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The ontogeny of 23 postcranial skeletal dimensions, mechanical properties of the third metatarsal and the femur, and the isometric contractile properties of the gastrocnemius muscle were measured in a complete postnatal growth series of the highly cursorial hareLepus californicus.Newborn hares are handicapped by short limbs, relatively weak muscles and bone tissue, and shorter muscular contractile distances. However, during growth these deficiencies are rapidly overcome. Hind limb length and gastrocnemius contractile distance undergo positive allometry, scaling as (body mass)0·39and (body mass)0·41, respectively. The mechanical advantage of the gastrocnemius lever system experiences negative allometry (a(body mass)‐0·12), giving young hares larger advantage around their joints. This, combined with initial positive allometry of gastrocnemius contractile force (α(body mass) 1·23) and subsequent negative allometry of contractile force (α(body mass)0·61), results in the production of relatively greater propulsive forces transmitted from the foot to the ground in juveniles than in adults. In addition, the second moment of area of the metatarsal is relatively large in younger animals, and scales in such a way that during the first half of postnatal growth mechanical similarity is maintained between the breaking moment of the bone (α(body mass)1·50) and the moment imposed on the bone by the gastrocnemius (a(body mass)l·54). These ontogenetic changes contribute to the development of a locomotor system which is effective at escape by the time the young hare is only 20% of adult body size, and must forage independently. Differences between the ontogenetic allometry ofLepus, the interspecific allometry of mammals and the ontogenetic allometry of reptiles are noted and considered in a phylogene

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb04259.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The breeding behaviour of Malaysian peacock pheasantsPolyplectron malacensewas studied in West Malaysian rain forest. Males maintained territories, within which some called from cleaned display areas. There were calling interactions between males but no stable dominance hierarchy. Females approached calling males at these display areas for mating. There were year to year variations in males' behaviour, apparently related to the food supply, and it is suggested that food levels may shift the balance between alternative mating strategies.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb04260.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Principal stresses acting in the midshafts of the radius and metacarpus of the horse were determined fromin vivostrain recordings during locomotion and jumping. Ground forces and limb position were also recorded. Over a range of speed and gait the radius was subjected to considerable bending, whereas the metacarpus was loaded primarily in axial compression. As a result, peak stresses acting in the radius (maximum: –45 MN/m2) were consistently 50% greater than those acting in the metacarpus (maximum: –31 MN/m2). The increase in peak bone stress (radius: 119% and metacarpus; 114%) with increasing speed was matched by a 103% increase in the mass‐specific vertical force (Av) exerted on the limb and a 55% decline in duty factor of the limb. The forelimb was closely aligned with the direction of ground force during the support phase (<9° when peak force acted) to minimize bending forces exerted on the distal limb bones. Hence, bending of the radius resulted mainly from axial forces acting about its longitudinal curvature. This was in contrast to the metacarpus, which is a much straighter bone.Significantly greater stresses were recorded in each bone during jumping: –81 MN/m2in the radius and –53 MN/m2in the metacarpus. While the distribution of loading in the radius was similar to that during steady state locomotion, greater variability in the magnitude and/or distribution of metacarpal loading was observed between animals, largely due to differences in the orientation of the limb during takeoff and landing. These data demonstrate that the horse, despite its large size, maintains a safety factor of nearly 3–4 during peak

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb04261.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Is there a predictable relationship between species‐typical behavioural development and social organization in mammals? Earlier work on canids and rodents suggested that adult sociality is associated with a developmental schedule in which juveniles showed, among themselves: (1) frequent social play; (2) frequent amicable contact; (3) frequent olfactory contact; (4) a delay in the emergence of agonistic behaviour. In the highly social Collared peccary (Tayassu tajacu) the behaviour of juveniles conformed only partially to this scheme. Juveniles engaged in social play with each other at an early age, but showed no other observable amicable or olfactory contact until eight to twelve weeks of age and showed no delay in the emergence of agonistic behaviour among themselves. Adults, in contrast, were conspicuously tolerant of juveniles, and 86% of juvenile social interactions in the first year took place with adult

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb04262.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The gross anatomy and histochemistry of the mucus‐producing glands ofLimax pseudoflavusEvans were investigated. The body mucus can be divided into three areas. The dorsal body surface is covered with a sulphated acid mucopolysaccharide/protein mixture secreted largely by five cell types. The pedal mucus is a mixture of neutral mucopolysaccharide from the suprapedal gland. The dorsal and pedal mucus sheets are separated by the peripodal groove whose cells secrete a weakly acid mucus. The duct of the suprapedal gland, the epidermis around the pneumostome, the ventral surface of the peripodal groove and the centre of the underside of the foot are ciliated. The dorsal and pedal mucus remain stationary relative to the body and the substrate respectively and the only rejection currents seen in the mucus are around the pneumostome.It is suggested that the pedal mucus is formed by the mixture of the products of the suprapedal gland and the mucoprotein secreting gland in the leading edge of the foot, thus producing a mucus suitable for locomotion. Many areas of the animal (e.g. the head, pneumostome, sole and the leading edge of the foot) are capable of producing both a fluid (neutral or weakly acid) and a viscous (acid) mucus. It is postulated that such an arrangement allows for both adhesion and lubrication at different time

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb04263.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

AdultHoplopleura erraticasucking lice were labelled using a setal clipping technique. Host exchange for lice marked in this manner was monitored through a small population of dye‐marked Eastern chipmunks, Tamias striatus, the normal host of this ectoparasite, in a deciduous woodland in central Tennessee, U.S.A. This was accomplished by frequent host live‐trapping, anaesthetization and pelage examinations. Louse transfer was most prevalent during the host summer mating period, presumably because of increased chipmunk contacts. At this time, 66·7% of marked adult lice within the host population transferred. Exchanges between opposite sex hosts were more common and adult males donated most lice; no juvenile chipmunks were recorded as louse donors. A greater proportion of male than female lice transferred. Using the exclusive boundary strip method, all exchanging chipmunks had overlapping ranges or shared at least one boundary

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb04264.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Two species of helicinid land snails, the Jamaican endemicEutrochatella pulchellaand the Cuban endemicViana regina, display a colour pattern of white spots on a greenish background. Microstructural and optical investigations of the shells have revealed that the colour patterns are non‐homologous. InE. pulchellathe white spots are associated with areas of granular shell structure, in which the crystals have an irregular, peak‐like form. InV. regina, there is no structural modification of the shell mineral associated with the spots. Modification of the organic matrix is responsible for the appearance of spotting. InV. regina, the shell pigment is yellow and located in the inner part of the shell. It appears greenish as seen from the outside through the translucent shell. The pigment fluoresces yellow under ultraviolet light. The greenish shell pigment of E. pulchella is non‐fluorescent and is uniformly distributed through the shell (except in the white spots).Since the colour patterns are non‐homologous, their similarity must have arisen through convergent evolution. The adaptive value of the colour patterns is thus indicated. Both species live exposed on limestone rocks and their colour patterns (at least in the case ofE. pulchella) cause them to be very cryptic. Predation by visually oriented predators (perhaps birds) is a probable cause of selection for shell colour pattern.The association of polymorphism with wide habitat breadth and of monomorphism with narrow habitat breadth is proposed. This relationship is seen in the two helicinid species, both of which show little within‐population variation as compared with polymorphic snails (e.g. helicids), which occupy a wide range of habitats. The generally monomorphic character of populations of Jamaican snails may be a result of habitat specialization associated with the unusually high species diversity on the island (some 450 species in 11,400 km2).The need for studies on the relationship of shell colour and structure is po

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb04265.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The dynamic similarity hypothesis postulates that different mammals move in a dynamically similar fashion whenever they travel at speeds that give them equal values of a dimensionless parameter, the Froude number. Thus, given information about one species, it could be possible to predict for others relationships between size, speed and features of gait such as stride length, duty factor, the phase relationships of the feet and the patterns of force exerted on the ground.Data for a diverse sample of mammals have been used to test the hypothesis. It is found to be tenable in many cases when comparisons are confined to quadrupedal mammals of the type described by Jenkins (1971) as “cursorial”. Most mammals of mass greater than 5 kg are of this type. Although the hypothesis applies less successfully to comparisons between cursorial and non‐cursorial mammals it is shown to be a reasonable approximation even for such comparisons and for comparisons between quadrupedal mammals and bipedal mammals and

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb04266.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY