摘要:

The scaling rate of metabolism with respect to body mass is analysed. Scaling of heat production implies that scaling also exists between temperature regulation and body mass. Most vertebrates follow a Kleiber relation down to a “critical mass, below which the scaling of metabolism must be changed to ensure the maintenance of endothermy. Such an adjustment is found interspecifically in birds and mammals, and is found intraspecifically in mammals during post‐natal growth. If the Kleiber scaling relation is maintained below the critical mass, mammals and birds shiR from endothermic temperature regulation (above critical mass) to endothermy with obligatory torpor (below critical mass). If the Kleiber relation is followed to masses far below the critical mass, ectothermy results. Critical mass varies inversely with the level of energy expenditure, which therefore accounts for the fact that most mammals and birds are endotherms and most reptiles and fish are ectotherms. The same relationship permits the facultative endothermy found in some insects and plants.The scaling relations existing among rate of metabolism, endothermy, and body mass can be written as a modification of the Kleiber relation. This analysis suggests that any organism, irrespective of phylogenetic position, can be endothermic at any body size, if its rate of metabolism is high enough, or can be endothermic with any rate of metabolism, if it is large enough. Consequently, it is difficult to distinguish minimal endothermy from inertial homoiothermy in animals having a large mass. The boundary conditions for effective endothermy are similar to the relationship described between metabolism and mass in the evolution of endothermy through a decrease in mass in the phylogeny of mammals. Even though endothermy may evolve with an increase in mass, its perfection may always require an evolutionary decrease in m

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb06114.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The adults ofStreptogonopus phipsoni(Pocock), an Indian polydesmoid millipede, emerge from the soil at the onset of the monsoon and mate. Eggs are laid in the soil and the adults die. The larvae leave the soil at stadium III and, apart from moulting periods, remain on the surface until the end of the monsoon. The larvae are aggregated in swarms, usually consisting of several hundred individuals. They are active on open ground, including metalled roads, during daylight, but usually spend the night in an inactive state under cover of stones or vegetation. If a swarm is disturbed, the individuals scatter but later reaggregate.Laboratory experiments show that the larvae are sensitive to light even though they lack eyes, and if given a choice spend more time in the light than the dark. Just before and after moulting however they spend more time in the dark than in the light.Experiments were carried out on the reactions of the larvae to aquatic suspensions of benzaldeyde, since this substance is related to components of the exudate of the repugnatorial glands; strong concentrations (10‐1) repelled the larvae, whilst weak concentrations (10‐6) attracted them. It is suggested that swarms may be dispersed or reaggregated by the effects of variations in concentration of components of the exudates. The benefits to the larvae which may result from swarming are discus

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb06115.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The relative size and the ultrastructure of the heart ventricle of a haemoglobinless and myoglobinless teleost,Channichthys rhinoceratus, has been investigated. It is two to three times larger than that of a red‐blooded species which also lives in the Kerguelen archipelago,Notothenia magellanica.At first sight, electron micrographs of the myocardial cell do not reveal peculiar features related to the absence of respiratory pigments. A mitochondrial compartment amounting to 18% volume fractions indicates a fairly high aerobic metabolis

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb06116.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

In this paper blood lead levels in three categories of Mute swan are examined, (i) flock birds (ii) breeding birds and (iii) cygnets. From these regional, seasonal and sex variation for both 1980 and 1981 was examined. In addition a portable haematofluorometer was assessed to determine its possible use as an alternative to atomic absorption and spectrophotometry for determining a measure of lead exposure.Very few swans on the River Thames had blood lead levels below the maximum acceptable level of 40 mgg/100 ml. In general lead levels increased with proximity to London and the swans on the tributaries consistently had the lowest levels which were always below the maximum acceptable level. Blood lead levels in flock birds were shown to be highest during the coarse fishing season and it was only during the close season that levels dropped to around 40m̀g/1OO ml. Breeding females had significantly higher lead levels than males and females with lead levels in excess of 200m̀g/1OO ml seemed to have a poor chance of producing cygnets or surviving to the next breeding season. Cygnet mortality was significantly higher on the lower Thames where blood lead levels were also known to be at their highes

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb06117.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The paper is a taxonomic study of the limneticDaphniapopulations of the English Lake District, the populations upon which the most popular taxonomic scheme is based (Johnson, 1952).Johnson treats these populations as three varieties of the speciesD. hyalina,namelyD. hyalinas. str.,D.h.var.galeataandD.h.var.lacustris.Careful examination of the populations of Esthwaite reveals that what has previously been regarded as a population of a single variety ofD. hyalina.includes three distinct forms. Experimental work confirms that these are genetically distinct. One of these forms corresponds toD. hyalinavar.galeata, whilst the other two are designated the “toothed” and “round‐headed” forms.The first part of the paper is concerned with the taxonomic status of var.galeata. Brooks (1957) and some later workers treat this as a separate species(D. galeata)on morphological grounds. This is fully supported by the present work. Differences between var.galeataand co‐existing forms in incidence of sexual reproduction, in vertical distribution and in seasonal abundance and average brood‐size provide further support for the separation ofD. galeata.The second part of the paper is concerned withD. hyalinas.str. which, on the basis of morphology, ecology and reproductive behaviour, is shown to be at least as distinct from other members of the complex as isD. galeata. It is argued that other forms should therefore to be removed fromD. hyalina. The taxonomic status and affinities of the remaining “toothed” and “round‐headed

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb06118.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The paper describes the relationships between adult age, hatching date, egg volume, brood size, hatching sequence, chick weight at hatching, chick growth rate and chick body size for a population of Great skuas in Shetland. The relative importance of these factors, and food availability, is assessed in determining chick size, weight, and growth rate.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb06119.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Fat deposits of463 Red fox vixens shot during autumn‐winter were monitored throughout a four‐year cycle of vole abundance (1975‐79) in south‐central Sweden. The growth ofjuveniles during the same period was indexed by lower jaw length during winter. The reproduction of foxes in the study area was correlated with vole abundance. Fat deposits built up during autumn and were depleted during winter. Subadults had consistently smaller fat deposits than adults. There was no positive correlation between vole abundance and mean fat deposits in autumn or degree of depletion during winter. The mean amount of fat deposited during autumn was correlated with the frequency ofoccurrence offruit and berries in fox stomachs. The degree of depletion of fat deposits during winter was correlated with mean snow depth. It is hypothesized that the availability of fruit and berries (a major source of carbohydrates in the diet of foxes) determines the amount of fat reserves built up during autumn, whereas the energy requirement of moving in deep snow determines the degree of depletion during winter. Juvenile growth was correlated with vole abundance but growth later in life seemed to compensate for this va

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb06120.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Aspects of the breeding biology of the Light‐mantled sooty albatrossPhoebetria palpebratawere studied at South Georgia. Its breeding distribution there is summarized and an annual breeding population ofc.5000 breeding pairs estiamted. Laying, hatching and fledgine dates are given, together with egg measurements and data on the duration of incubation and brooding shift. Chick growth in weight and wing length from hatching to fledging was followed in detail.Breeding season adaptations ofP. palpebrataare compared with those of the other three albatrosses at South Georgia. The slow chick growth ofP. palpebrataresults in a nestling period even longer than those of the two larger mollymawks and is attributable mainly to the lower frequency of feeding resulting from the highly pelagic existence of adultP. palpebrata.Comparisons are made with other breeding populations and especially with that on Marion Island. This is basically very similar and differences in chick growth patters are suggested to relate to differences in diet and particulartly to the frequency with which chicks receive foo

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb06121.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY