摘要:

A study spanning two breeding seasons was carried out to examine the role of androgens in the control of the frontal and gular scent glands of the marsupial sugar gliderPetaurus brevicepsWaterhouse in a wild population. Animals were captured at monthly intervals and from these blood samples were taken and tissue biopsy samples were collected from the scent glands.Several histological parameters underwent seasonal changes which were related to changes in the plasma concentration of free plus albumin bound (‘biologically active’) testosterone. The parameters which showed significant change did so during the July‐September breeding season coinciding with the peak in biologically active testosterone concentration.Castration caused a significant decrease in the nuclear diameters of gular and frontal apocrine and sebaceous gland cells, and a decrease in gular apocrine cell height. These decreases were reversed with androgen replacement therapy.The nuclear diameters of apocrine tissue cells in both scent organs are positively correlated with the plasma level of biologically active testosterone. In the gular organ, but not in the frontal organ, the depth of apocrine tissue was significantly correlated with nuclear diameter. In castration and androgen replacement studies gular apocrine tissue responded more dramatically than did frontal apocrine tissue. This suggests that the gular organ is more sensitive to testosterone than is the fr

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb03797.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The bathyergid mole‐rats provide a unique example of a family of subterranean rodents exhibiting a broad spectrum of sociality. Three genera comprise solitary, strongly territorial individuals whereas two genera are social. This sociality culminates in the eusocial naked mole‐rat,Heterocephalus glaber. The pups of solitary mole‐rats disperse, establish and thereafter defend their own burrow systems when approximately two months old, whereas those of social genera join an established natal colony. This paper examines whether these different lifestyles are reflected in the early development and rate of growth of pups of mole‐rats.Although the trends are not clear‐cut, it is apparent that the pups of solitary genera grow and mature more rapidly than those from social genera. Thus, the growth rate constant (K) for the first70–80 days of postnatal growth (using the Gompertz equation) for the solitary genera was between 0.042 and 0.052 day−1, whereas that of the social mole‐rats was considerably lower (0.01 5 day−1). Similarly the mean growth rates of solitary genera ranged between 3.3 and 1.227g/day while those of the social mole‐rats were 0.229‐0.233 g/day.The pattern of development and the rates of growth in solitary bathyergids are similar to those of other solitary subterranean rodents. One interesting feature common to all the social genera studied to date was that the first pups recruited to a ‘new colony’, consisting of a reproductive pair of adult mole‐rats, grew at a significantly faster rate than pups bo

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb03798.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The innervation of free neuromast (sensory papillae) rows is described from Sihler wholemount preparations of four species of eleotridine gobies, one (Perccottus glenii) representing the ‘longitudinal’ type of neuromast arrangement, the others (Butis buits, Bostrychus urophthalmus, B. marmoratus) the ‘transverse’ arrangement. In the latter, the characteristic transverse cheek rows (1–7) are innervated from the infraorbital trunk of the anterior lateral‐line nerve. Longitudinal cheek rowsbandd, and the three opercular rows,ot, osandoi, common to all species, are innervated by rami of the hyomandibular trunk of the same nerve. Two neuromast groupings are shown to have a mixed nerve supply. For the median preorbital snout rows, there is innervation from the infraorbital (s3andr) as well as the supraorbital (s1ands2) trunks of the anterior lateral line nerve. The anterior dorsal rows are supplied both by the posterior lateral‐line supratemporal ramus (rowsgandm) and the anterior lateral‐line supraorbital trunk (rowsoandn). The neuromast rows, under the designations of Sanzo, are tabulated according to innervation and their putative origin in the phyletic replacement of a complete head canal system seen in more generalized pe

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb03799.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

We have begun an intensive series of investigations into the environmental and endocrine mechanisms regulating cooperative breeding in a semi‐arid tropical environment. A colour‐marked population of white‐browed sparrow weavers (Plocepasser mahali) was studied at a field site near Nyamaluma Camp, Luangwa Valley, Zambia (13dG S). This species breeds from October to April, although some clutches may be found as early as August and young may be fed until May.Non‐disruptive techniques were employed to monitor annual cycles of gonadal development, body mass and fat reserves, and small blood samples were collected to measure circulating levels of reproductive hormones and corticosterone. All individuals were released after sampling and the social and reproductive activities recorded by systematic behavioural observations. Each individual could thus be identified as: (1) a breeding adult; (2) a related helper (i.e. offspring of the breeding male and female within the group); or (3) a non‐related (=invader) helper (these birds helped defend territory but did not help feed young; they were not related to the breeding pair and usually originated from outside the group).Breeding males had larger testes and higher levels of testosterone than either related helpers or invader helpers. In females, all status groups had follicles up to 2 mm in diameter, but only breeding females ovulated. There were no differences in plasma levels of reproductive hormones among different status females, except for higher circulating luteinizing hormone (LH) in invader female helpers during the first part of the breeding season. Although plasma levels of testosterone were highest in breeding males, the maximum titres were two orders of magnitude less than in males of passerine species from temperate regions. Furthermore, injections of a peptide hormone GnRH (gonadotropin‐releasing hormone) increased plasma LH levels in both males and females, and were followed by rises in testosterone levels only in males, but not over the normal maximum seen in February. GnRH‐induced high levels of LH did not affect testosterone concentrations in the blood of females.Results obtained thus far indicate that the hormonal control of aggression in white‐browed sparrow weavers is different from that predicted by investigations on north temperate species. Whether these phenomena are typical of tropical species, particularly cooperative breeders, remains to be determined. Since most of the world's species of birds live in the tropics, and a substantial fraction of them breed cooperatively, more investigations are needed to establish the hormonal basis of reproductive behaviour and cooperative breeding. Given the baseline data already collected, the white‐browed sparrow weaver will

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb03800.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The mite Antennophorus grandis (Berlese, 1903) is a large obligate ectoparasite of workers of the ant Lasius flavus(Fabricius). It rides under the head of the ants and uses its long front legs to communicate with its hosts and stimulate them to give it food. We present allometric and morphometric data showing thatL. flavusworkers can occur in two size classes. We also present the first quantitative ethograms of mite‐bearing and mite‐freeL. flavusworkers of the two size categories. The mites tend to occur on the smaller nurse workers and receive food from them at an extremely high frequency.Antennophorus grandisalso frequently gain food when one ant is donating food to the one they are riding upon. The mites seem to inhibit the ability of their host worker to show most social behaviours such as tending ant larvae. The mites frequently move from one host worker to another. For these reasons the mites may have a larger impact upon their host colony than their relative rarity first suggests. The ants do not seem to have any specific defence against these parasites. The mites live in small populations and show female‐biased sex ratios consistent with local mate competition. Preliminary evidence suggests that the mites have haplodiploid sex determination which may explain how they are able to adapt their sex allocation to their population

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb03801.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The development of vocalizations during post‐natal growth in the microchiropteran batPipistrellus pipistrellusis described. Vocalizations served as precursors of echolocation sounds and as isolation calls used to attract mothers. Although calls judged to be echolocation precursors tended to be of short duration and possessed high rates of frequency modulation when compared with isolation calls, a wide spectrum of intermediate calls existed making classification diffuse. Changes in the frequencies and durations of calls during growth are described. Multiple discriminant analysis showed considerable inter‐individual variation in isolation calls, while the calls of any individual were remarkably consistent in their structure at both six days and 15 days of age. The relative importance of acoustic call parameters in contributing towards inter‐individual variation changed between six days and 15 days. Vocal signatures of youngsters were probably important in allowing a mother to identify her own offspring in a creche thus preventing misdirected maternal care in this species, though vocal signatures of infants changed during development. Echolocation calls of flying juveniles were compared with calls from their mo

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb03802.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The stages of permanent tooth development observed in radiographs of the mandible are described and analysed for known‐aged red deer (Cervus elaphus). The ages by which the different stages of development were reached have been determined. By allocating scores for these different stages, the scores that may be expected for a particular age have been identified. Lastly, the predicted age was given, together with 95% prediction intervals obtained from a regression of age on total molariform scores. Tooth development in red deer was usually completed by 33 months. These data can be used to assess the ages of animals of unknown ag

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb03803.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The process of weaning is related to a critical or threshold body weight attained by offspring among large‐bodied mammals; the anthropoid primates, ungulates and pinnipeds. While weaning weight was allometrically related to maternal weight in interspecific comparisons, it was isometrically related to neonatal weight. When a neonate had grown to four times its birth weight, it was weaned. Differences between taxonomic groups were found only among the fasting phocids, where weanlings attained a lower, but proportional, weight. The duration of lactation was only weakly allometrically related to maternal or neonatal weight, and varied between individuals intraspecifically as a function of maternal condition. The time to weaning appears to be ecologically sensitive rather than to reflect interspecific life‐history variation, in that, irrespective of the time to weaning, similar proportional weights appear to be attained. Interspecific similarities in threshold weaning weights are suggested to result from constraints on maternal abilities to meet energetic requirements of offspring through lactation after infants attain a threshold wei

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb03804.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Three badger (Meles melesL.) setts in the south of England, which formed a single sett complex belonging to one social group of badgers, were excavated prior to being destroyed by construction of a new road. Setts 1 and 2, classified as annexes, were excavated completely; sett 3, classified as a main sett, was only excavated partially, but its total size was estimated from the excavated portion. The setts consisted of tunnels totalling 16 m, 140 m and 879 m, respectively; contained one, nine and 50 chambers; and had five, 42 and 178 entrances. The total volume of the three setts was about 45 m3, and their construction was estimated to have required the removal of about 70 tonnes of soil. In the two smaller setts tunnels ran on a single level with an average depth of 99 cm; in the larger sett they ran on two levels with modal depths of 50 cm and 110–120 cm, respectively. All three setts contained bedding material (dry grass and plastic bags) but only the main sett contained latrines. None of the setts contained badger bones and the interiors of all three setts were remarkably clean and orderly. We discuss hypotheses as to why badgers sometimes continue to extend even large well‐established setts but conclude that the survival value of very large setts remains problemati

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb03805.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Sexual encounters were staged in the laboratory among hormonally‐primed Iberian midwife toads,Alytes cisternasii. In this species, pairing and fertilization are terrestrial. The male cares for the developing embryos on land, carrying them twined around his hind limbs until they hatch into tadpoles which he releases into water; his investment in the offspring then ends. The courtship ofA. cisternasiican be divided into a pre‐ and post‐ovulatory phase. An encounter is initiated when the female approaches the male and is clasped by him in inguinal amplexus. Both the male and the female produce vocalizations during the period prior to the initiation of amplexus. During amplexus, only the female vocalizes, changing her call to one that is of lower intensity, longer duration and more regularly emitted than before. During inguinal amplexus, the male engages in bouts of intense pedalling and gentle rocking behaviour, each bout being initiated when the female repositions herself beneath him. Rocking and pedalling cease when the female ovulates, at which time she exhibits a posture that we call Unkenkrampf. Ovulation occurs at this time, and is followed by sperm release by the male (seen as a series of lateral compressions of his body). After sperm release, the male moves forwards to engage the female in cervical amplexus and then manoeuvres his hind limbs such that the egg string becomes tangled around his ankles. The female may exhibit additional episodes of Unkenkrampf during this period, but these are not accompanied by further egg release. Episodes of Unkenkrampf (without ovulation) also may occur after the male dismounts from the female. Similar behaviour patterns to those observed in the laboratory are seen in natural populations ofA. cisternasii. We compare and contrast our observations ofA. cisternasiiwith those of other authors for this species and also for the common midwife toad,A. obster

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1991.tb03806.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY