摘要:

Multiple group principal component analysis is used to investigate the relationship between morphometric characters in inbred and hybrid House mice. Weight is shown to be largely independent of linear size, and character relationships within inbreds are shown to be the same as those within hybrids. Multiple group principal component analysis is largely successful in defining general size and shape components in the Osteometric characters. General size accounts for most of the within‐group variation–in spite of the isogenicity, uniform rearing, and uniform age of the mice. Both size and shape are less variable in hybrids than in inbreds. Heterosis is apparent for general size and one component of shape, whilst dominance is widespread amongst the shape components. Canonical analysis is used to investigate inconsistency in the direction of dominance between individual components and the overall direction of domina

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb05097.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Studies were carried out during the spring, summer and autumn seasons of 1974–1976 on a natural population of the terrestrial snailBrephulopsis bidens(Pulmonata: Enidae), located on a mountain in Crimea (USSR). The overall population was characterized by a high density (50.2–124.4 ind/m2in 1974, 61.3–162.5 ind/m2in 1975 and 27.8–157.3 ind/m2in 1976) and a strongly pronounced congregational tendency of snails. There was a significant correlation (r=087,P

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb05098.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The methods used to study the populations of the Bank vole and Long‐tailed field mouse on Skomer Island in 1981 are described. The survey was a repeat of one performed in 1960 and the methods used were almost identical.The distribution of both species of rodent over the island was studied using trap lines and was found to be similar in both surveys.The vegetation of the island was divided into nine categories and the habitat preferences of both rodent species assessed. These have remained distinct and, as in the previous survey, the voles were found to be most strongly associated with areas of deep bracken with little undercover and the mice with open areas such as cliff tops and rocky outcrops.A crude survey of the distribution of the nine vegetation categories was undertaken, a vegetation map was prepared, and the area of each category was estimated. Two trapping grids were established in vegetation categories favoured by the voles. The data from these grids were used in conjunction with the vegetation map to estimate the population of voles over the whole island. Insufficient data were available for such an estimate to be made of the size of the population of mic

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb05099.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The gaits of domestic kittens between one week and six months of age were analysed according to the methods of Hildebrand (1976, 1977) to determine how gait preference and performance changes during normal ontogeny. Allometric growth of the limb segments was measured so that mechanical effects on gait behaviour could be described. Gait behaviour during ontogeny follows a pattern of increasing precision and diversity that parallels the attainment of neuromuscular maturity: one‐ and two‐week old kittens use very slow, stable walking gaits. By three weeks of age, walking patterns are more diverse and kittens begin to trot. At four weeks, animals are trotting more readily and begin to use slow gallops. Neuromuscular maturity is attained by about six weeks of age and these animals use all of the gaits common to adults. Evidence that the ontogeny of behaviour reflects a recapitulation of neural evolution is discussed.Important mechanical changes occur in the posture and limb proportions of kittens during ontogeny that markedly affect their gait performance. Until six weeks of age, kittens are plantigrade or semiplantigrade, resulting in functionally shortened limbs. The foot segments were found to be relatively long in kittens up to 12 weeks of age. While plantigrade, these long feet provide large bases of support, but are awkward to move heel‐to‐toe, and may contribute to the need for the most stable footfall patterns in young kittens. With fully digitigrade posture achieved between six to eight weeks of age, the long foot segments result in relatively longer limbs. At eight weeks, this is reflected in their preference for the pace while walking to avoid interference between ipsilateral limbs. These behavioural modifications of gait patterns in response to transient mechanical constraints support a facultative view of neural

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb05100.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Black‐backed jackalsCanis mesomelaswere studied in three areas in Southern Africa, by means of radio tracking, visual observations and ear tagging. Jackal pups moved from the close proximity of their natal dens at 3 months of age, but stayed in the vicinity of the dens for at least 6 months. Dispersal often occurred at an age of about 2 years, mainly during the winter. Adult jackals had smaller home ranges than younger animals. Adult home ranges were inhabited by mated pairs. These ranges were mutually exclusive and differed in size between study areas. The home ranges of immature jackals overlapped extensively with those of the adult jackals. Some young jackals acted as helpers in rearing the pups at natal dens, while others roamed over large areas. Adult jackals move over longer daily distances than did younger animals. The significance of the division of Black‐backed jackal populations into breeding and non‐breeding components is discussed as well as the similarities among the social systems ofCanis mesomelas. C. aureus and C. la

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb05101.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The growth and cellular composition of the thymus, spleen and kidney were monitored in Rainbow trout,Salmo gairdneri,from 1 to 15 months of age. All organs grew as the fish grew, but they attained their maximum relative weights (expressed as a percentage of body weight) at 2–3 months ofage. The organ weights showed a closer correlation to body weight than they did to age. The total number of leucocytes in the lymphoid organs increased with age; however, the number per gram of lymphoid organ tissue, and per gram of tissue per gram of fish, decreased with age. The number of cells present showed a closer correlation to the weight of their respective organ, than they did to age. A histological study of the lymphoid organs showed gradual changes in the structure of the lymphoid tissues. The thymus showed some signs of involution even at 15 months of age. The spleen and kidney had mixed populations of erythrocytes and leucocytes, with a gradual increase in the amount of melanin as the fish aged. The kidney in particular had a rich variety of leucocytes. The blood picture showed no obvious fluctuations with age or season over the period studied, with the proportion of lymphocytes present remaining remarkably constan

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb05102.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

A multivariate analysis was made of the mandible shape of wild‐caught House mice from the British mainland, various circum‐British islands and Faroe.Shape variation within any one of the three archipelagoes—Faroe, Shetland, Orkney—is greater than within mainland Britain excluding Caithness. This is probably due to the founder effect, as well as reduced subsequent swamping.The grouping of Caithness mice with those of Orkney, Shetland and Faroe may reflect their Scandinavian

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb05103.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

RarelyGasterosteus aculeatuspopulations occur where many individuals have lost their protective dorsal spines, ventral spines, pelvic girdle and lateral bony plates. Reduction in predation pressure is currently viewed as the causative factor.On the lsle of North Uist (Outer Hebrides) 10 spine‐deficientG. aculeatuspopulations, sympatric with various fish and bird predators are described. All of the spine‐deficient morph sticklebacks are found in acidic oligotrophic peat moorland lakes and pools where Ca2+is ≤ 2.5 mg/1. It is proposed that calcium deficiency may have been an important selective agency in the evolution of skeletal reduction in these unusual popula

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb05104.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Caecilians have evolved a unique, dual jaw‐closing mechanism that consists of the ancestral component in which theM. adductor mandibulaepulls up on the lower jaw in the manner of a third‐order lever, and a novel component in which theM. interhyoideus posteriorpulls back and down on the retroarticular process of the lower jaw causing the anterior jaw ramus to pivot upward around the quadrate, as in a first‐order lever. The novel component involves the acquisition of a new function for theM. interhyoideus posterior, which ancestrally is a ventral constrictor. The novel component is relatively poorly developed in rhinatrematids, a family of caecilians that is otherwise relatively primitive and is characterized by skulls with temporal fossae through which the twoM. adductor mandibulaeextend. The novel component is better developed in the other four caecilian families, all of which are thought to be relatively derived groups, and the members of which mostly have solidly roofed (stegokrotaphic) skulls. The skull of ancestral caecilians is thought to have had temporal fossae, which later became closed as the novel component of jaw‐closure became better developed, perhaps in response to selection pressure for burrowing specialization. If this sequence is correct, then the stegokrotaphic skull of caecilians is secondarily derived, and the hypothesis that caecilians arose fromGoniorhynchus‐like microsaurs with stegokrotaphic skulls is incorrect. Lysorophid microsaurs, which have skulls with open temporal regions, are more likely ancestors of c

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb05105.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

A pond was completely enclosed by a clear polythene barrier and all toads entering and leaving were recorded over an entire year. The inward breeding migration lasted one month, and the outward migration about one month for females and two months for males. Interruptions in the numbers arriving during the inward migration could be explained by low air temperature. Large males and females arrived before smaller individuals, and males arrived before females, staying about a month, four times longer than females. During the breeding season 865 individuals were captured; the male: female ratio was 4.7: 1. Relatively few toads visited the pond during the summer, but at this time the imbalance in the adult sex ratio was not so great as during the breeding season. Juvenile toads also visited the pond during the summer. It appears that females suffer a mortality rate of about 4.7% per week during their stay in the pond and males a rate of 2.6% per week.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb05106.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY