摘要:

A decline in recent decades in the status ofRana temporariain the British Isles has been attributed to a number of factors, mostly relating to increased urbanization. Acidification has recently been suggested as a factor which could affectR. temporariapopulations in certain areas.The effects of acid water and aluminium on the embryonic development ofR. temporariawere investigated using eggs obtained by artificial fertilization from frogs caught in two widely separated areas; an upland area (acidic ponds) and a lowland area (circumneutral ponds). The eggs were kept in artificial soft water at either pH 4.5 or pH 6.0 and with aluminium concentrations covering the range measured in water from the acidic ponds.The survival of embryos to normal free‐swimming larvae was not affected by water pH in the absence of aluminium. Increasing aluminium concentrations reduced the survival of lowland embryos in circumneutral water, but upland embryos were unaffected. However, in acidic water the survival of embryos from both areas decreased with increasing aluminium concentrations. Embryos which did not survive either died early in development, or developed gross abnormalities, or were constricted in the perivitelline membrane and failed to hatch. The body length of surviving larvae was decreased by both increasing aluminium concentrations and low pH, probably owing to a reduction in growth rate rather than development rate. The body length of larvae from upland ponds was decreased less than that of lowland larvae in acidic water, suggesting a greater acid tolerance in embryos from acidic ponds.Reduced embryo survival, sublethal effects, such as reductions in embryonic growth rate, and indirect ecological effects may affect recruitment to the adult population in acid ponds. It is not possible to predict from the present data what effects these results of acidification may have on regional population because the acid tolerance of embryos varies widely within region

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02585.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Radiotracking and live‐trapping were used to describe spacing patterns ofDasyurus geoffroiialong the Murray River in Western Australia. Both sexes are essentially solitary, and occupy numerous dens which define stable core areas. Female core areas typically showed little or no mutual overlap, suggesting that females are intrasexually territorial. As an exception to this, a non‐dispersing daughter may share her mother's core area and successfully rear young there. Transient females were rarely encountered, and vacant female core areas were eventually occupied by juveniles known to have been born on the study area. Male core areas were much larger than those of females, and overlapped broadly with those of other males as well as females. In captivity, females deposit scent by cloacal dragging in response to odours left by foreign conspecifics, and both sexes tend to defecate at sites already containing faeces. In the wild, faecal aggregations occurred throughout the areas used byDasyurus, but were especially well developed in places where animal movements were likely to be concentrated, such as paths and river crossing poi

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02586.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The milk intake of suckling tammar wallabies (Macropus eugenii) was estimated between 213 and 339 days of age using a double‐isotope procedure in which tritiated water (TOH) was injected into the dams and deuterium oxide (D2O) injected into the offspring. Recycling of isotopes between mothers and offspring was shown not to be a significant source of error. Estimates of body water (isotope dilution space) in the mothers or offspring, as a proportion of their body weight, were similar to values obtained with other macropodids and with placental mammals (0.73–0.75). Total water inflow in the offspring increased throughout the period, but the proportion of this contributed by milk fell in sigmoid fashion from 95.6% at 213 d to 3.7% at 340 d. Milk intakes reached a peak of about 86 ml/d, which was low compared with placental species. Before the peak, intakes were more closely related to body weight than age. Peak milk intake corresponded with the period of emergence from the pouch. Milk intakes were also in excellent agreement with published data obtained earlier in lactation, in animals drawn from the same population. These data were therefore combined to provide estimates of intake for the whole of lactation in the tammar wallaby, and algebraic models fitted to describe the pattern of milk intake in relation to body weight or age. With body weight, the pattern of milk intake was well described by a rising linear phase to a peak intake of about 86 ml/d near 1110 g body weight, followed by a gradual exponential decline. When related to age, the pattern was well described by a rising logistic phase (peak at 251 d) followed by a sharp exponential decline. It is shown that this latter pattern is markedly similar to the shape of the functions describing the energy requirements for the sum of pregnancy and lactation in a placental species, the sh

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02587.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The intake of milk components (total solids, carbohydrate, protein, lipid, energy) by suckling tammar wallabies (Macropus eugenii), from peak lactation to independence, was measured using a double‐isotope dilution technique and chemical analysis of milk samples. The time of peak intake of milk solids (day 256 of lactation or 1126 g of offspring weight) was similar to that for whole milk. Peak intake of carbohydrate occurred earlier than this (235 days) and peak intakes of protein and lipid occurred later (262 days and 266 days, respectively). Intake of gross energy peaked at 262 days and represented a maternal yield of about 207 KJ.Kg‐0.75.d‐1. This is much lower than peak lactational energy yields in most other mammals, but the duration of lactation is longer in tammars than in other mammals. Total output of energy in milk by tammar mothers was 63 MJ, and this would require an intake of about 98 MJ of metabolizable energy in food. This requirement, which is equivalent to 21 MJ/kg of maternal weight, is similar to those calculated for sheep and cattle, suggesting that there are not large differences between marsupial and placental herbivores in terms of weight‐related allocation of energy to reproduction. We suggest that a strategy of minimizing the peak energetic demand of lactation may be an important adaptation for a small, primarily grazing mammal due to size‐related physiological constraints on elevating herbage intake and the increasing risk from predators when grazing time is

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02588.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Changes in the plumage of the wandering albatrossDiomedea exulanswere studied on the Crozet Islands, using a population of birds of known sex and age and including some birds more than 32 years old. Plumage phases of a cross‐section of the male and female populations are presented. Males and females fledge with a dark brown plumage. Between the first and fourth year the male's plumage becomes much whiter than the female's. Between five and 15–18 years old the whitening of plumage in either sex develops in parallel though still separated by the extent of the initial divergence. Male plumage probably attains a definitive snowy stage after 30 years while the plumage of the female does not mature beyond an intermediate stage, which is reached after 20 to 25 years. Maturation of the plumage of head, back and wing are compared. In birds of similar age, breeding birds tend to have a whiter plumage than non‐breeders. In the oceanic range of the species, white birds, i.e. mostly adult males, favour cold antarctic waters while dark birds, i.e. mostly adult females and juveniles, are observed in warmer subtropical and subantarctic waters. We discuss the possible adaptive significance of the slow maturation in the plumage of the wandering albatross and of the differences in plumage between sexes and between popula

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02589.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Morphometric, histological and histochemical investigations were carried out on the ventral buccal salivary glands of the Arabian camel (Camelus dromedarius). The ventral part (inferior molar gland) is composed of serous acini with abundant myoepithelial cells and the dorsal part of the gland comprises mucoserous acini. The serous acini are devoid of any type of mucosubstances while the mucoserous cells of the dorsal part show neutral glycoproteins and sialomucins but neither glycogen nor sulfomucins. The histoenzymological tests employed have detected alkaline phosphatase, adenosine triphosphatase, succinic dehydrogenase, non‐specific esterases and α‐amylase but no activities for aminopeptidase, lipase, cholinesterases and β‐glucur

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02590.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The weight gain in lactating harbour seal pups and sex‐specific growth curves are described. The relationship between body length, body weight and age were derived by regression analysis based on length and age data from 365 seals, and weight values from 136 seals. The asymptotic values of the curves describing body length were 148.0 cm and 147.2 cm in females and 153.9 cm and 155.5 cm in males using Gompertz and von Bertalanffy, respectively. The corresponding body weight values were 72.8 kg and 76.7 kg in females and 90.7 kg and 88.4 kg in male

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02591.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

There has been much uncertainty in the past concerning the identity of the pterygoid bones in Siluroidei (catfishes). This confusion stems from the often increased number of pterygoid elements and their modified development, as compared with other teleosts. The ontogeny of the hyomandibula‐pterygoquadrate series in a 20‐day developmental sequence ofCorydoras paleatus(Jenyns, 1842) embryos is described and supplemented with observations on a clariid and an ageniosid. A historical résumé of previous interpretations of siluroid pterygoid bone homologies is given together with our own which regards the metapterygoid as the central, densely ossified area of the pterygoquadrate, surrounded by the membranodermal ento‐ and ectopte

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02592.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Red and grey brocket deer and collared and white‐lipped peccary of the Peruvian Amazon are frugivores and consume many types of seeds. The ruminant stomach of brocket deer functions as a mechanism to digest the abundant hard palm seeds ofIriarteasp.,Euterpesp. andMauritia flexuosa. The sympatric peccaries also consume hard palm seeds; however, peccaries crack these palms by using their strong jaws, thick skull bones and interlocking canines. The ruminant stomach might have evolved as a means to digest structural components of seeds, similar to that employed by extant brocket deer, since ancestral ruminants appear to have evolved as smallbodied, forest‐dwelling frugivo

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02593.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

First recorded from Hong Kong in 1980,Mytilopsis salleinow dominates the intertidal pier community within the Government Dockyard, Victoria Harbour. Analysis of monthly samples ofM. salleihas demonstrated aspects of the reproductive strategy and life‐history characteristics correlated with seasonal changes in local water quality.Mytilopsis salleiis dioecious, has a high fecundity, matures early (at 8–10 mm shell length), grows fast and the majority of the population is probably semelparous. These are characteristic traits of opportunisticr‐strategists. Comparable characteristics are typical of other introduced bivalves. Maximum life span ofM. salleiin the Dockyard is probably less than 20 months with, however, most of the population dying before that. Heavy recruitment, particularly during spring‐summer, suffocates older individuals. The shells of dead animals similarly last for little more than one year, dissolution and crushing effecting this. A mat of byssal threads serves to bind the mass and anchor it to the substratum.Mytilopsis salleiexhibits two periods of reproductive activity and settlement per year. These are possibly two elements of a single recruitment divided into minor (autumn‐winter) and major (spring‐summer) components by either high summer temperatures or low salinities. Summer and winter recruits ofM. sallei, respectively, mature to produce the summer and winter juveniles of the following year. Over‐stepping generations plus survival of a few individuals into their second year thus ensure continued success ofM. sallei, and account for its spread and dominance in its introduced range. Such a bimodal pattern appears typical of many Hong Kong intertidal, estuarine and freshw

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02594.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY