摘要:

Compared with European Red deer, Scottish Red deer stags are remarkably small. Previous research has shown that this may be primarily due to nutritional, rather than genetic reasons. The present study tested the hypothesis that poor nutrition, especially during the first winter of life, prevented the stags from reaching their genetic potential size. The study was carried out at Glensaugh Research Station on 20 newly weaned Red deer assigned to either of two groups, one fed a high plane of nutrition during the winter, the other a low plane. The trial began in December 1977 and in May 1978 both groups were released into a 200 acre paddock. In September 1978 some of each group were slaughtered. Despite considerable compensation by the low plane winter nutrition group there were significant differences in live weight, antler length and carcass weight at slaughter. It is considered that Scottish Red deer stags reach the maximum size that the environment can maintain despite this being far below their genetic potential.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb04267.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

A 12‐month investigation of the population dynamics, growth, ageing, reproduction and sexuality ofAnodonta woodiana(Lea, 1834) in Plover Cove Reservoir, Hong Kong, has been undertaken. Recruitment occurs in the summer, May through July being the period of peak incidence of glochidia on captive fish hosts. Juveniles grow rapidly to a shell length of 30 mm and are sexually mature by the following spring. A study of the population structure ofA. woodianaindicated that most animals were less than 8 years old. Results of a Walford plot for this species indicated a maximum theoretical shell length (in Plover Cove) of 162·5 mm and a life span of approximately 12 years; the latter is in good agreement with age estimates for European unionids.Anodonta woodianais dioecious with females predominating in a ratio of 60:40. A very small number of individuals (0·3%) are hermaphrodite. Males possess mature gonads throughout the year whereas females come into reproductive condition during the spring. There was no evidence of shell form sexual dimorphism, as has been recorded for other unionaceans.The reproductive strategy and time of gonad maturation ofA. woodianais compared with that of unionids from elsewhere and with other fresh water bivalves from southern Ch

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb04268.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The general structure of the skin of the Lesser octopus,Eledone cirrhosais described. The component regions and cell types being (1) the epidermis, composed of columnar cells with a border of microvilli on their external surface, mucous cells and secretory cells of an unknown type, abutting a non cellular basal lamina; (2) the dermis, containing the elements of the colour change system, vascular and neural processes and an a cellular matrix.A sequential, morphological study of wound closure revealed three major mechanisms in the healing response; muscular contraction, a dermal cellular reaction and epidermal migration. The process of wound closure inEledoneis significantly slower than that seen, for example, in teleost fish (30 h rather than 30 min for the initiation of epidermal migration). The significance of these results in relation to the osmotic balance between seawater and the internal milieu ofEledoneis discussed, together with their relevance to resistance against infection by pathogens.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb04269.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Existing data indicate that a greater preponderance of adult females rather than adult males occurs in most species of mammals. The hypothesis that such differences arise as a result of intermale reproductive competition for females (and not predation) was examined in the Equidae by comparing populations of horses (Equus caballus), asses (E. asinus), and two species of zebras (E. zebraand E. burchelli) in predator‐free, predator‐rich and insular ecosystems.Evidence is presented that: (1) sex differences in adult mortality occur; (2) they relate to the type and intensity of natural predation; and (3) asymmetries in sex ratios are most often explicable in terms of intermale reproductive competition. Exceptions are discussed and they are complicated by numerous proximate fact

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb04270.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

In a Red‐billed quelea colony in north‐eastern Nigeria that was later abandoned as a result of the poor nutritional condition of the adults, laying females showed low haematocrit values compared with normal pre‐breeding haematocrit levels but nestbuilding males did not. In females the low haematocrits were correlated with extremely low levels of reserve lipid and labile protein but males in equally poor condition did not have such low haematocrits. This difference must result in some way from the additional nutritional burden for females of mobilizing sufficient protein to form eggs. Earlier observations of massive red blood cell production in the thymus of queleas during incubation suggest that low haematocrits, indicating anaemia, may be a normal occurrence in queleas during breeding, and were not peculiar to this abnormal abandoned c

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb04271.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

In the regular echinoidDiadema setosumLeske the central ligament that connects the spine to its tubercle is mainly composed of closely‐packed collagen fibres which are arranged in the longitudinal axis of the ligament. The mechanical properties of the ligament are quite different from ligament to ligament: the viscosity determined by creep tests ranges from 0·02 to 6 GPa·s. The viscosity of a ligament changes reversibly in response to stimulation. Adrenaline and noradrenaline (10‐6‐10‐3M) decrease the viscosity. Acetylcholine (10‐8‐10‐3M), artificial sea water containing high (100 MM) potassium concentration, and electrical stimulation increase the viscosity. As the ligament contains no muscle cells in it, the viscosity change cannot be attributable to muscle activities. The functional significance of having a central ligament with variable and controllable viscosity is that it binds the spine base onto the articulation surface of the tubercle, so as to reduce the possibility of spine dislocation, while being flexible enough to allow the spine considerable freedom of movement

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb04272.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The breeding behaviour of a Common toad (Bufo bufo) population was studied at a breeding pond on Portland, Dorset. Major toad movements towards the breeding pond occurred on warm, wet nights when the temperature did not fall below 6°C. Males arrived earlier than females resulting in an initially exaggerated sex ratio which then slowly reduced as the breeding season progressed. No size assortative pairing was found although large males were more successful at mating than small males. Although males demonstrated no ESS (evolutionary stable strategy) in searching for a female between sites within the pond evidence suggesting the existence of one between the pond and an undefined area surrounding it was found

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb04273.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The use of eye lens weight, tooth eruption and tooth attrition has been investigated as a method for age determination in the hyrax. Illustrations are presented on the stages of eruption to reduce subjectivity of eruption criteria and to aid age determination. All teeth are fully erupted and in wear by five years of age, from which point age determination can be based on attrition of M3. Growth with age is described by means of the von Bertalanffy equation. Asymptotic weight is reached by 60 months, asymptotic body length and body girth by 40 months, and hindfoot length by 35 months. The asymptotes and the coefficient of catabolism (K) are compared with values obtained in other studies.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb04274.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

InLampetra planerithe epidermis of adult and ammocoete contains a type of bipolar cell, with numerous microvilli about 1 μm long on the apex, and the base associated with a nerve fibre by bar‐type synapses. These multivillous cells can be identified with types found by previous authors. In the ammocoete, they correspond to those previously described as epidermal photoreceptors, which were shown to be innervated from the lateralis nerves; this is consistent with the mode of innervation seen by electron microscopy. A pigment seen in the photoreceptors is presumably represented by an organelle consisting of a tangle of microcylinders or tubules, associated in tetrads. The organelle can be called a sinnet, from its configuration. In adult skin, multivillous cells have a close resemblance to the receptor cells of the end buds of adult lamprey epidermis, but they are not associated with supporting cel

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb04275.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Levels of progesterone in peripheral plasma samples showed a mean (± S.E.M.) ovarian cycle length of 28 ·63 ± 1·01 days (n= 19).The preovulatory, or follicular phase (mean ± S.E.M. length: 8·25 ± 0·30 days,n= 56) was defined as that period of the cycle during which progesterone levels remained below 10 ng/ml. The postovulatory, or luteal phase (mean ± S.E.M. length: 19·22 ± 0·63 days,n= 48) was defined as the remaining period of the cycle during which levels remained between 10 ng/ml and 150 ng/ml.The day of ovulation (day 0) was defined as that preceding the day on which progesterone levels first exceeded 10 ng/ml (day l), at the onset of the luteal phase. Oocytes and preim‐plantation embryos recovered from the reproductive tract provided supporting evidence for the timing of ovulation.The short follicular phase indicated that follicular growth may be initiated during the previous luteal phase. The long luteal phase may be related to the extended period of preim‐plantat

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb04276.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY