摘要:

The masses of the locomotor and acardiac muscles of wild barncale goose gollings, from migratory population, were examined systematically during development and their values compared to those of pre‐migratory geese. Pre‐flight development was typified by approximately linear increases of body, leg, and heart ventricular mass with respect to age. Flight muscle showed an exponential increase in mass. Pectoralis muscle mass was 14.2 ± 0.3% of body mass (1297 ± 73g, n=7) in early flying goslings compared to 16.6 ± 0.3% of body mass (2318 ± 109g, n=8) in pre‐migratory geese. Post‐flight development was typified by stasis of leg muscle mass but hypertrophy of Ventricular and pectoralis muscle mass in proportion to body mass. Ventricular mass relative to body mass showed the lowest values at 5 weeks of age (0.62 ± 0.01%) with peak values at 1 week of age (10.4 ± 0.04%). The latter may be associated with both requirements of thermoregualation in these precocial, arctic breeding geese and the need to forage approximately 24 hours post‐hatch. Peak values for leg muscle mass, relative to body mass, were found at 3 weeks of age (12.7 ± 0.36%), with lowest values in the pre‐migratory geese (6.7 ± 0.21%), while peak values for pectoralis muscle mass were expressed in the premigratory geese with lowest values at 1 week of age (0.94 ± 0.07%). Ventricular mass was proportional to leg muscle mass up to 5 weeks of age (Mv= 0.38Mt0.68, r2=0.95), but subsequent increase in ventricular mass was proportional to pectoralis muscle mass (Mv= 0

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1996.tb05432.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The social Matabeleland mole‐ratCryptomys hottentotus nimrodioccurs in both the high‐and lowveld of Zimbabwe. The population in the highveld has a mean (± S. D.) resting metabolic rate (RMR) when acclimated for three months in the laboratory of 0.83 ± 0.04cm3O2g‐lh‐l(n=12) within the thermoneutral zone (TNZ) of 31‐32°.The body temperature (Tb) within the thermoneutral zone is low 34.4 ± 0.18 (n= 12) and remains stable at ambient temperatures (Tas) from 25‐32°. Above 32°, Tbincreases albeit slightly to 36.6 ± 1.46° (n= 12). The conductance is high 0.17 0.02cm3O2g‐1h‐°‐1(n= 24) at the lower limit of thermoneutrality. The mean RMR at 18° (the lowest Tatested) was 2.29 ± 0.11 cm3O2g‐1h‐1, which is 2.75 times that of the RMR in the TNZ.The population in the lowveld has a mean (± S.D.) resting metabolic rate (RMR) when acclimated for three months in the laboratory of 0.95 ± 0.07 cm3O2g‐1h‐1(n= 12) within the themoneutral zone (TNZ) of 28‐30 °.The body temperature within the thermoneutral zone is low 34.0 ± 0.23 (n= 12) and remains stable at Tas from 25‐30 °. Above 32 °,Tbincreases, albeit slightly, to 37.8 ± 1.14 ° (n= 12).The conductance is high 0.14 ± 0.09cm3O2g‐1h‐1°‐1(n= 24) at the lower limit of thermoneutrality. The mean RMR at 18 ° (the lowestTatested) was 1.96 ± 0.12cm3O2g‐1h‐1, which is 2.0 times that of the RMR in the TNZ.These thermoregulatory parameters are compared with published dat

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1996.tb05433.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

In an analysis of data collected between 1954 and 1993, the breeding success of swiftsApus apuswas found to have been positively related to temperatures in June, especially in recent years. Adult survival until the next breeding season, by contrast, was found to have been more vulnerable to low temperatures in July, at the end of the breeding season. In addition to the effects of changes in June and July temperatures, both breeding success and survival have shown further long‐term trends, increasing and then decreasing through the study period. A simulation integrating all these effects suggests that lifetime reproductive success (LRS) in influenced more by changes in lifespan than annual breeding success, and so fluctutations in July temperatures, but not June temperatures, would have important effect

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1996.tb05434.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

To evaluate effects of persistent bot fly (Alouattamyia baeri) parasitism on a host population of Panamanian howler monkeys (Alouatta palliata), a 68‐month study was carried out which included: (i) examination of the parasite's life cycle; (ii) monthly estimates of prevalence and mean intensity; (iii) monitoring of howler mortality; (iv) censuses of howler monkey troops; and (v) analysis of blood samples from infected and uninfected monkeys. A complete life cycle ofA. baeritakes approximately 13 weeks; larvae remain in howlers for approximately six weeks, passing through three instars. Overall prevalence of infection was 60%, overall mean intensity 2.8±0.04. No difference in prevalence or mean intensity was found between adult males and females. As a class, juveniles had a significantly higher prevalence and a significantly lower mean intensity than adults; the adult and juvenile classes both showed a significantly higher prevalence and mean intensity than the infant class. Such differences may relate to characteristics of younger age classes rather than host selectivity on the part of the parasite. Although larvae were observed in the howler population throughout the year, relative density fluctuated from month to month, showing from one to three significant peaks per year. Larvae were most abundant during the mid‐to‐late rainy season (Aug.‐Nov.). Relative density was strongly correlated with howler mortality. Several hematological parameters including serum albumin levels and albumin/globulin ratio were significantly lower in individuals with heavy larval burdens. No endoparasites or diseases were found in blood samples. I conclude that the annual pattern of howler mortality results from a synergistic effect between the age, physical condition, and fat reserves of parasitized individuals, the size of the larval burden, and increasing dietary stress as the rainy season progresses. The lack of growth in this closed primate population over>20 years apparently results, in large part, from primary and secondary effects of bot fly pa

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1996.tb05435.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Thrichomys apereoidesis an echimyid rodent which ranges in distribution from north‐eastern and central Brazil into Paraguay, and currently five subspecies are recognized. Recent morphometric analyses of population samples formally assignable toT. a. laurentiusandT. a. inermis, which occur in north‐eastern Brazil, have shown that a major group of populations including both subspecies differ in cranial shape from a single population allocated toT. a. laurentius. In this study we employed mathematical models of evolutionary quantitative genetics to assess the role that random drift and selection may have played in the evolution of cranial shape differences inT. apereoides. The hypothesis of evolution due to drift was rejected and the selective forces necessary to account for shape differences were estimated. Minimum selective mortalities of the order of 10‐3of per generation were sufficient to explain the observed morphologic differenti

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1996.tb05436.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The prey and feeding frequency in free‐living grass snakes was studied during 1993 and 1994 at a site in southern England. Individual snakes and common toads were recognized using PIT tags and a small number of adult snakes were radio‐tracked over long periods to determine predation rates.Grass snakes fed, almost exclusively, on common toads (adult, juvenile, and tadpoles). A positive correlation was found between prey size and snake size. Large snakes did not appear to prey upon small toads, although clearly capable of doing so.Male and female snakes ate large meals (toads) approximately every 20 days between May and September, with females fasting for a period of about 45 days during gestation and egg‐laying. After allowing for differences in the number and size of toads predated by male and female snakes, the mean amount of food consumed per day was estimated to be 2.3% and 1.6% of body w

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1996.tb05437.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The body size of specimens ofTriturus marmoratus pygmaeusfrom Doñana is the smallest recorded for this subspecies. Snout‐vent length averages 42.3 mm in males, and 43.9 mm in females. Mean body mass in males is 2.04 g and 2.29 g in females. The age of newts was estimated by means of skeletochronological methods. The maximum longevity recorded was 10 years in females and nine years in males, with one or two years being the age at maturity. As in other newts, body size is not a good predictor of age, since a wide range of body length was found within each age class. Growth in females was substantial in subsequent years, showing an overall positive tendency. However, males showed slight or even negative growth. Newts from Doñana are different from other nearby localities with similar climatic characteristics. This is mainly due to their short juvenile and terrestrial ph

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1996.tb05438.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Patas monkeys (Erythrocebus patas) have aquamarine‐coloured scrota, but data are unavailable regarding the potential connection between changes in scrotal coloration and testicular function. In the rhesus monkey (Macaca mulatta), seasonality of mating is accompanied by an intensification of red colour of the scrotum and a doubling of testicle size. A one‐year study of male patas monkeys was undertaken in order to examine potential seasonal correlates of testicular function and scrotal colour. Increases in testosterone concentrations and testicular volume occurred during the mating season in adult males, but scrotal colour was fairly uniform throughout the year. Neither age, body weight, nor health influenced scrotal colour. These findings contradict the suggestion that the sex skin of seasonally breeding primates will become more intense during the mating season as a result of elevations in steroid hormone levels. Evidence from field studies in Africa suggest that the colour is part of a constellation of traits involved in male competition for ma

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1996.tb05439.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The propagation of vibrations along the trunk and branches of a manuka tree, generated in response to the impact of a steel ball‐bearing on the trunk, was measured with an accelerometer. The impact generated bending waves which travelled along the trunk and into the branches. Close to the point of impact the waveform was dominated by a damped oscillation at 518 Hz; as the bending wave progressed away from the point of impact the frequency of the dominant waveform increased. Beyond 200 cm the waveform became increasingly complex and a smallamplitude, high‐frequency component progressively preceded the main wave. Branching points also induced complex waveforms, particularly where branches lay at a large angle to the trunk. Stridulating wetas also generated bending waves in the tree at a frequency close to that generated by the ball‐bearing, as well as at a higher frequency of 7.5 kHz. The acoustic frequency of stridulation peaked at 0.8 and 3.4 kHz. Records from nerves serving the vibration‐sensitive subgenual organs showed that wetas can detect oscillations at 1 kHz at 0.015ms‐2. A stridulating weta placed on the same log as a preparation in which the nerve from the subgenual organ was monitored generated oscillatins well above the threshold for

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1996.tb05440.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The northern bottlenose whale has been caught in the Faroe Islands for centuries, with written catch records going back to 1584 and unbroken from 1709. A total of 811 whales has been reported in the period 1584‐1993. The Faroese bottlenose whaling is an opportunistic drive fishery of pods sighted very close to shore. Natural strandings also occur. Most of the fishery has taken place in two close southern villages of the Faroese archipelago (72% of the catch). The high season is 20 August‐20 September. The pod contains 1‐7 whales with an average of 2.1 whales. Most of them are immature males or mature females with juveniles, but as many males as females have been caught overall. Females and males at every stage of development have been caught in the Faroes, although it appears that the bottlenose whales approaching the Faroese coast and then driven ashore have not included as large and as small individuals as those shot offshore. A body weight (W in kg) and length (L in cm) relationship has been calculated for both sexes combined: W = 0.0000131 x L3.07. Females and immature males have a grey and bulbous forehead. As the males mature their forehead becomes flatter and lighter, and only large mature males have a white and flat forehead. The stomach contents of nine whales contained in total at least 13 squid species. A comparison with pilot whaling shows that bottlenose whales arrive 2‐4 weeks later than the pilot whales and that the geographical distribution of the catch is very different for both species, suggesting a different pattern of migration through the arch

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1996.tb05441.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY