摘要:

The sex ratio in five populations of the sheetweb spiderPityohyphantes phrygianusin southwest Sweden was investigated in July and September, the spiders being juveniles and subadults, respectively. In July, no heterogeneity between the five populations was found and the pooled samples revealed a sex ratio of 36% males and 64% females. A significant heterogeneity in sex ratio was observed in the September samples; the proportion of males varied between 23% and 40%. In several cases, male mean weight differed significantly between the five populations, comparing the July and September samples separately. This suggests that the prey availability varied considerably between the sites. In September, dead spiders were collected in two sites. This mortality was probably caused by starvation and the mortality rates differed significantly between the two sites. Indirect evidence suggested that the local sex ratio was affected by the prey availability, males being at a relative disadvantage in poor sites. Local environmental conditions may govern the adult sex ratio in this spider by causing differential mortality and/or migration.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02470.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The aim of this paper was to describe how the age, sex and reproductive state of hares affected the amount of fat found around their left kidney. A total of 2208 hares (Lepus europaeus) was shot and autopsied over 13 years from sub‐alpine grasslands in Canterbury, South Island, New Zealand. Adult females may be pregnant from July to mid‐March. Adult males' testis weights were highest from July to January, and some fertile males may have been present in all months but April. The amount of perirenal fat in adults increased in autumn, peaked in early winter, and decreased thereafter to low levels through spring and summer. Autumn fat deposition in males was not clearly related to reproductive state in individuals, although it coincided with seasonal testicular development. Autumn fat deposition in females may have been caused in part by the cessation of lactation, but, like that in males, the increase was also part of an endogenous pattern. Fat utilization in winter was related to breeding. In males, utilization coincided with reproductive activity and the amount of perirenal fat remained consistently low throughout the breeding season. In females, net fat utilization was associated with lactation but this was balanced to some extent by fat deposition induced by pregnancy. Females simultaneously lactating and pregnant were in finer balance between utilization and deposition. Other factors, such as the number of embryos and the stage of gestation, altered the fat balance in these hares. Fat was also deposited as a ‘yolk‐sac’ i

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02471.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The lateral fins of cuttlefish and squid consist of a tightly packed three‐dimensional array of musculature that lacks bony skeletal support or fluid‐filled cavities for hydrostatic skeletal support. During swimming and manoeuvring, the fins are bent upward and downward in undulatory waves. The fin musculature is arranged in three mutually perpendicular planes. Transverse muscle bundles extend parallel to the fin surface from the base of the fin to the fin margin. Dorso‐ventral muscle bundles extend from dorsal and ventral connective tissue fasciae to a median connective tissue fascia. A layer of longitudinal muscle bundles is situated adjacent to both the dorsal and ventral surface of the median fascia. The muscle fibres are obliquely striated and include a core of mitochondria. A zone of muscle fibres with a more extensive core of mitochondria is present in both the dorsal and the ventral transverse muscle bundles. It is hypothesized that these muscle masses include two fibre types with different aerobic capacity. A network of connective tissue fibres is present in the transverse and dorso‐ventral muscle masses. These fibres, probably collagen, are oriented at 45 to the long axes of the transverse and dorsoventral muscle fibres in transverse planes.A biomechanicayl analysis of the morphology suggests that support for fin movements is provided by simultaneous contractile activity of muscles of specific orientations in a manner similar to that proposed for other ‘muscular‐hydrostats’. The musculature therefore provides both the force and support for movement. Connective tissue fibres may aid in providing support and may also serve for elastic e

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02472.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Complete burrow systems of the mole ratSpalax ehrenbergi(Rodentia; Spalacidae), from two sites on Mount Carmel in Israel, with different soil types (terra‐rossa and rendzina), were excavated and described here for the first time.A comparison was made of burrow structure patterns in the two soils and of the sexes, with special attention to the features of the feeding tunnels.The pattern in the rendzina revealed longer burrows with a longer main tunnel and fewer branches per metre of the main tunnel, while the pattern in the terra‐rossa revealed shorter burrows with a shorter main tunnel and a relatively higher number of branches. These differences can primarily be related to the different levels of food availability, which is higher in the terra‐rossa. It is suggested that each of the patterns reflects the mole rat's ability to optimize foraging efficiency in accordance with its given food availability.The average total length of the males' burrows was much greater than those of the females' burrows in the rendzina soil. It appears that food requirements determine different burrow features of the sexes rather than reproduction requirements.Other tunnel features (e.g. structural complexity, depth and width, segment length and spatial arrangement) and the factors which may affect them, as well as burrow structure of young mole rats and evidence of the underground dispersion of young mole rats, were presented and discussed.Many similarities were found in a comparison ofS. ehrenbergiburrow features with those of other solitary subterranean ro

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02473.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Euphaea decoratain Tai Po Kau Forest Stream (Hong Kong) was univoltine. Most recruitment took place in summer, and larval growth proceeded throughout the year. Life‐cycles recorded in 1977–78 and 1978–79 were similar. Annual production estimates, using the removal‐summation, instantaneous growth and size‐frequency methods, were more similar for the 1978–79 generation (ranging from 158.7–174.7; mean 1671 mg dry wt m‐2) than for the 1977–78 generation (93.9‐173‐6; mean 131.7 mg dry wt m‐2). Mean biomass was similar for both generations (ranging from 33.5–33.9 mg dry wt m‐2), and mean P/B ratios were 3.9 1977–78) and 5.0 (1978–79). These are the first estimates of annual production by an Oriental stream insect.Larvae were most abundant at microsites in the middle of the stream. Multiple regression analysis indicated that substratum characteristics were a major determinant of microdistribution.Euphaea decorataapparently favoured poorly‐sorted sediments with highly peaked grain size‐frequency distributions, containing few fine particles.The carnivorous larvae showed ontogenetic changes in diet. Small individuals consumed mainly chironomid (Diptera) larvae; the diet expanded to include (successively) larvae of Ephemeroptera and Trichoptera asE. decoratagrew. Seasonal changes in diet were also apparent, although larval diets during spring and summer were similar. There was also considerable overlap between autumn and winter diets. Ontogenetic influences upon prey consumed were not sufficient to account fo

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02474.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Measurements of the rates at which droppings of wall lizards (Podarcis muralis) on Jersey appeared in, and disappeared from, the environment made it possible to formulate a simple mathematical model for the dynamics of faecal pellet populations. The model shows how, for a given lizard population, the number of droppings changes with time according to weather conditions. It was used to estimate lizard densities at a number of sites from daily pellet counts. There were significant differences in the densities of lizards between sites; possible reasons for these are discussed.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02475.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Studies are presented on the pulmonary circulation of three Himalayan marmots (Marmota himalayana(Hodgson)) captured in the mountains north of Lhasa, Tibet. The pulmonary arterial pressure and resistance were low, the right ventricle was not hypertrophied and the arterioles and terminal portions of the muscular pulmonary arteries had thin walls. The observations suggest that this species has adapted through natural selection to high altitude by losing the capacity for hypoxic pulmonary vasoconstriction.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02476.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Body measurements of squirrel populations are described. The relation between body length and body weight was examined and factors causing individual or seasonal variation in body weight were studied.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02477.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Acid phosphatase, non‐specific esterase, alkaline phosphatase, monoamine oxidase and true lipase activities, in the epidermis ofNatrix piscatorin different stages of the sloughing cycle, have been localized using various histochemical techniques.Different layers in scale epidermis have staining properties similar to corresponding layers in hinge epidermis.Acid phosphatase and non‐specific esterase activity in cell layers undergoing keratinization, and the lacunar tissue undergoing disintegration are associated with hydrolytic and catabolic wasting processes involving cell death. The activity of these enzymes in the clear layer is associated with the breaking down of the cementing substance resulting in the separation of clear layer from underlying tissue and facilitating the shedding of old slough.Alkaline phosphatase activity in the stratum germinativum and undifferentiated epidermal cells has been associated with cell proliferation and differentiation. The presence of alkaline phosphatase in the lacunar tissue and clear layer has been correlated with the synthesis of mucopolysaccharides in these layers.Monoamine oxidase and true lipase activity could not be located in the epidermis at any stage of the sloughing cy

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02478.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Carbohydrate histochemistry of the scale and hinge epidermis of the chequered water snake,Nalrix piscator, throughout the sloughing cycle, has been described. The small amount of mucopolysaccharide present in the Oberhautchen, mesos layer, α‐layer and β‐Mayer (in its initial stage of differentiation) is comparable with that in amphibian epidermis and the epidermis of certain freshwater fish undergoing keratinization. Moderate amounts of mucopolysaccharide in the lacunar tissue and clear layer may protect against environmental pathogens and retain water to protect the epidermis from desiccation. Mucous cells could not be located in the epidermis throughout the sloughing cycle, contrary to some previous observations that they occur in the hinge region. The general absence of glycogen in the epidermis in most stages of the sloughing cycle suggests that the glycogen metabolized in the epidermis is utilized immediately, in view of the high energy requirements of proliferation and differentiation. Accumulation of glycogen granules in the presumptive α‐layer in stage 2 and in the clear layer, presumptive Oberhautchen and presumptive β‐Mayer in stage 3 is correlated with low energy requirements, indicating a slowing down of the process of keratinization of cells in t

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02479.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY