摘要:

Agonistic displays of larvalDiphlebia euphoeoides, an amphipterygid damselfly, are described. Damselflies are conventionally regarded as consisting of two broad taxonomic divisions, namely ‘narrow‐winged’ damselflies and ‘broad‐winged’ damselflies. Agonistic displays are known from many larval ‘narrow‐winged’ damselflies. This is the first description of agonistic behaviour in the larva of a ‘broad‐winged’ damselfly. Twenty six major displays were distinguished. Several new major displays, unlike those described for any other odonate larva, were found. Other display motor patterns showed a strong similarity with those recognized in larval Coenagrionidae. Such displays probably represent symplesiomorphies. The potential use of larval agonistic display characters in phylogenetic analysis is discussed. Contrary to recent hypotheses on turnover of agonistic displays, change within odonate lineages

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02617.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Adipose tissue was dissected completely from 21 female and two male Svalbard reindeer killed in the wild in December 1989. The gross mass, mean adipocyte volume, collagen content, the maximum activities of hexokinase and phosphofructokinase and the fatty acid composition of triacylglycerols were measured in samples of adipose tissue from at least 14 superficial, intraabdominal, cardiac and intermuscular depots homologous to those of other terrestrial mammals. The total adipocyte complement was calculated from the mass of each depot and its site‐specific adipocyte volume. Almost all the adipose depots found in other terrestrial mammals were present. Site‐specific differences in adipocyte volume were pronounced but, in contrast to other mammals, the glycolytic capacity of intermuscular adipose tissue was only slightly greater than that of other metabolically active depots, possibly because this subspecies does not naturally perform prolonged, strenuous exercise. All metabolically active depots except the cardiac adipose tissue enlarged with increasing fatness, but the superficial depots expanded more than any of the internal depots. Partitioning between anterior and posterior superficial depots was variable, with the posterior depots enlarging slightly more than the anterior depots. The adipose tissue in the hoof and around the eye was metabolically inert, but that of the bone marrow and the knee had low but detectable glycolytic capacity. The hoof and knee depots contained a high proportion of collagen, suggesting that they are load‐bearing structures.There was no statistically significant correlation between fatness and mean adipocyte volume and differences in fatness were due mainly to differences in adipocyte complement. Cell proliferation may be the principal mechanism of adipose tissue expansion in all superficial, intraabdominal and intermuscular depots studied. The total adipocyte complement was about twice that predicted from allometric equations relating adipocyte complement to body mass in other mammals and did not increase with age. There were no significant differences between lactating and non‐lactating females in any of the parameters measured. The mean volume of intra‐orbital adipocytes corresponded closely to that predicted from allometric equations. There were more unsaturated triacylglycerol fatty acids in the outer sides of the superficial depots and in other peripheral sites such as hoof, eye and distal marrow, indicating some biochemical adaptation to cooler periphera

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02618.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Behavioural observations of both captive and free‐ranging sand and mountain gazelles revealed differences in group size and composition, territory size and agonistic behaviour. Sand gazelles are seasonal breeders and form large herds (maximum = 56) during rut and post‐rut as compared to mountain gazelles, which breed throughout the year in smaller groups (maximum = 5). As a result, mountain gazelle males maintain their territories year round, whereas sand gazelle rams show marked morphological changes and defend a territory only during the rut. Mountain gazelle males exhibited threat displays rather than engaging in actual combat more often than did sand gazelles. Although subject to the same environmental conditions, sand gazelles are seasonal breeders and the young are born in March‐April, whereas mountain gazelles give birth throughout the

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02619.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The effect of maternal age and condition on the date of parturition and the duration of the perinatal period of Antarctic fur seals at Bird Island, South Georgia, were investigated over three consecutive breeding seasons. Females rear young during a four‐month lactation period in a highly seasonal but predictable environment. Although females may first pup at three years of age, they did not attain full adult size until six years of age; older females (≥ 6 years) tended to be heavier, longer, and in better condition than younger females (3–5 years). Older females returned to breeding beaches earlier and could occupy the most suitable pupping sites, and gave birth when densities of animals on the beaches were low (i.e. more favourable for pup survival). Females that arrived earlier were able to remain ashore longer with their pups prior to departing on their first foraging trips but this was unrelated to either maternal age or condition. Younger females returned later in the pupping season, possibly as a result of late implantation due to smaller energy reserves than older and larger females. In 1990 all females arrived late, were in poorer condition, gave birth to lighter pups, and had shorter perinatal periods. This suggests that not only was implantation late but that females returned to an area of low food availability prior to partur

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02620.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

A new species of pterobranch has been found that has features that could resolve the longstanding arguments by palaeontologists about how the fossil graptolites produced their elaborate extra‐corporeal homes. Many complex and biologically highly unlikely solutions previously proposed can be simplified. This animal is probably classifiable as a graptolite and thus a living fossil, representing a group thought to be extinct for 300 million year

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02621.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Euglandinawas collected over a three‐year period in four habitat types in Mauritius. Smaller collections were also made in Reunion and Rodrigues. The areas in which theEuglandinawere collected were simultaneously sampled for potential prey species. Identification of the stomach contents and comparison with the available prey shows that most prey are eaten whole and that native species are eaten in greater numbers that would be expected form a consideration of their numbers in the habital.Achatinaspp., whichEuglandinawas originally introduced to control, was not positively identified in the diet. Even if all unidentified prey fragments were formAchatinathen this would form less than 5% of the total number of items in the stomachs.Habital destruction, together with predation byEuglandina, appear to be major contributors to the extinctions of native Mauritian snails. The conservation of primary forests, into whichEuglandinahas not penetratd, is suggested as the most effective way to save the remaining endemic ground‐dwelling snails form extinction. These results add further emphasis to the importance of preventing introductions ofEuglandinato areas with native snail faunas, and show clearly that this predator is not a successful control agent forAchat

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02622.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Skuas, which are closely related to gulls, frequently use a specialized feeding method (kleptoparasitism) by which they rob other seabirds of their food. This paper tests the idea that skuas have evolved as specialist kleptoparasites.The fibre type composition of the M. pectoralis, M. supracoracoideus and M. iliofibularis of a great skuaCatharacta skua(Brünn.) and a herring gullLarus argentatus(Pontopp.) was determined by three enzyme histochemical methods commonly used for mammalian fibre classification; the reactions for alphaGPDH, NADH‐TR and mATPase activity.In both species slow fibres were present only in the M. iliofibularis, and fast twitch glycolytic fibres were not present in any of the muscles. The M. pectoralis and M. supracoracoideus of both species consisted entirely of the fast twitch oxidative‐glycolytic fibres.The overall metabolic enzyme activities of the muscles were assessed in terms of the proportions of fibres with high, intermediate and low metabolic enzyme activity. The overall levels of oxidative and glycolytic enzyme activity were significantly higher in the M. pectoralis than in the M. supracoracoideus and significantly higher in both of these than in the M. iliofibularis. This was true of both species.The oxidative and glycolytic activities of all three muscles of the great skua were significantly higher than those of the homologous muscles of the herring gull. This was particularly true of the M. pectoralis and M. supracoracoideus. It is suggested that this difference between great skuas and herring gulls enables the former to be more effective aerial kleptoparasites than the la

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02623.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

We have studied a series of natterjack populations with varying densities of adults on the three main habitat types (lowland heaths, coastal dunes and coastal marshes) occupied by this species in Britain. Animals were aged by skeletochronology, condition was assessed by measuring weight length ratios in autumn and home ranges were determined by individual‐marking and by radiotelemetry. Female longevity was inversely correlated with population density, but no similar effect was observed for males. Uniformity of growth rates, absolute growth rates and mean condition for both sexes were also inversely related to population density, whereas mean home range showed a positive correlation. Taken together the data indicated that in high‐density populations natterjack toads grew more slowly and erratically, were in poorer condition and foraged much more widely than their counterparts in low‐density popula

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02624.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Anti‐predator defence behaviour of Argiope appensa (Fuesslin) (Araneae, Araneidae) was studied in the laboratory. The most frequent response of adults and large juveniles of A. appensa to disturbance was pumping, a behaviour during which this web‐building spider moved its body rapidly up and down with its legs remaining on the silk. When disturbed, small juveniles differed from adult females and larger juveniles by often dropping from the web instead of pumping. Argiope appensa sometimes put its web betweeen itself and stimuli from potential predators by shuttling from one side of the hub to the other.Argiope appensaoccasionally tugged on the web but this behaviour appeared to be primarily a component of prey‐catching sequences instead of defence. Experiments were carried out to determine the types of stimuli that elicited pumping. Lightly touching the spider or its web, forcefully hitting the web, and air movement elicited pumping but there was no evidence that chemical stimuli from potential predators were impo

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02625.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

We tested the hypothesis that hind limb proportions may be used to predict locomotor performance in a sample of 49 species of primarily cursorial mamals. Data on maximal sprint running speeds taken from published sources were related to measurements of hind limb lengths. To control for statistical complications due to the hierarchical nature of phylogenetic relationships, we used Felsenstein's (1985) independent contrasts method for analysing comparative data, and a composite phylogeny for all 49 species, based on a variety of published sources. The independent contrasts method indicates that maximal running speed does not covary significantly with body mass for this sample of mammals (mass range= 2.5–2,000 kg). Even though quality of the available speed data is highly variable, both metatarsal/femur ratio—the traditional index of ‘cursoriality’ in mammals—and hind limb length (corrected for body size) are significant predictors of maximal running speed. When only fully curorial species are included in the analyses (n = 32), hind limb length still significantly predicts speed (r2= 16%), but MT/F ratio does not. Although ungulates tend to have larger MT/F ratios than do Carnivora, they are not generally faster; relatonships between speed and limb proportions within the two clades show no significant differences. These and previous results suggest that hind limb proportions and maximal running speed may not have evolved in a tightly coupled fashion. Prediction of locomotor performance of extinct forms, based solely on their limb proportions, should be undertaken wit

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02626.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY