摘要:

Wild house mice,Mus musculus, were bred in (a) warm (control) and (b) cold laboratory environments. More pairs were barren in the cold than in the warm. Fecund pairs in the cold reared fewer young than controls, but their litters were larger at birth and their young were heavier. Nestling mortality declined over ten generations in the cold. Adult mice in the cold were heavier than controls, but not longer. Mice of the tenth generation in the cold, transferred to the warm environment and bred for three generations, were heavier, fatter and more fertile than the controls, but had lighter heart, stomach and kidneys. The secular changes observed were probably genetically determined, but may have included a maternal component.SummaryWild house mice,Mus musculusL., were trapped, and their descendants reared, in permanently mated pairs, for a number of generations in two laboratory environments, at about 21°C (controls) and ‐3°C, respectively. All mice had sawdust and cottonwool for bedding; but the nests of those at ‐3°C were colder than those in the warm, and fluctuated greatly in temperature.Reproductive performance was inferior in the cold environment: more pairs were barren, and the fecund pairs reared fewer young than the controls. Yet litters at birth were usually larger in the cold, and the young at three weeks were always heavier. Over ten generations nestling mortality declined at ‐3°C.From generation 1 on, adult mice at ‐3°C were heavier than the controls, but there was no corresponding increase in body length. Tails were much shorter relative to body length in the first generations in the cold, but returned to control proportions by generation 10. Most of the structural changes in the cold accord with the “rules” of Bergmann and Allen.The incidence of abnormal sixth lumbar vertebrae was low in all generations at both temperatures.After nine generations, some mice were transferred from the cold to the warm environment, and bred for a further three generations. There they outstripped the controls both in reproductive performance and in growth. They also had more fat, and a heavier and longer small intestine; but the heart, stomach and kidneys were lighter than those of the controls. Adrenal weights at 21°C declined over the generations, but those of the mice at ‐3°C did not.The secular changes observed, especially those in the cold environment, are attributed principally to differential selection of genotypes, not to inbreeding; but maternal effects may als

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1975.tb05975.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Variation in mean cell volume of the ciliateColpidium campylumStokes is described in relation to energy consumption, temperature and population density. Mean cell volume was unaffected by temperature and population density, while energy consumption had a marked effect. A linear relationship existed between mean cell volume and energy consumption up to an energy intake of 8000 μJ during 24 h by each individual present at the beginning of each experiment, above this level of energy intake mean cell volume maintained a maximum.SummaryWithin the temperature range 10°C‐20°C, temperature had no effect on the mean cell size ofC. campylum.Population density also exerted no noticeable effect on mean cell volume. The quantity of energy consumed, however, had a marked effect. In experiments where less than 8000 μJ were consumed/individual/24 h, the mean cell volume decreased. Above this level of energy consumption mean cell volume maintained a constant level.The maximum values obtained for cell sizes were 160–190 × 103μm3and the minimum values 40–100 × 103μm3. A response to decreased food concentration and hence decreased energy consumption was obtained within the 24 h experimental period, indicating a rapid response to changed environment by

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1975.tb05976.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Patterns of colonisation and breeding behaviour were observed in part of the Grey seal rookery at North Rona during the entire breeding season in 1972.Bulls came ashore when pupping started and joined cows grouped around pools. Numbers of cows and bulls increased to maxima in three and five weeks respectively. Limited access to the rookery and the presence of pools and waterlogged ground influenced site selection by cows.In the study area the breeding season lasted for 74 days, with individual bulls staying for periods varying from 6–57 days. Daily ratios of bulls to cows varied, but the average ratio was 1:7‐5. It was estimated that 275 cows participated in mating, compared with 37 bulls, during the entire breeding season. The interval of 18 days between peak numbers of cows and bulls ashore corresponded closely with the average time that cows spent ashore.The aggressive responses of cows in mating behaviour were noted during observations of 114 copulations. It was concluded that a bull requires a very strong sexual drive in order to overcome a cow's aggressive responses, and this reinforces the selective advantage of aggressive dominance in bulls. The stimulus inducing a bull to attempt mating seemed to be the presence of oestrous cows in the rookery rather than an individual cow being in oestrus, because the number of attempted copulations increased even when the number of cows in oestrus temporarily declined during the season. Direct observations and calculations using an index of copulation suggested that the copulation frequency for individual cows ranged from 2.5‐3.6. A bull's participation in mating, and therefore, its genetic influence, was related to the length of its stay in the rookery, and from this evidence it was deduced that a social hierarchy existed amongst the bulls.Appraisal of the results led to the conclusion that the Grey seal bull maintains a high level of sexual activity so as to mate with as many cows as possible, rather than ensuring exclusive access to cows through territorial fighting and boundary di

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1975.tb05977.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Births and postnatal behaviour were observed at a breeding assembly of Grey seals on North Rona. Birth is extremely rapid and the cow immediately turns to smell the pup. Smelling continues at intervals, particularly during the first 10 min after birth and allows the cow to establish the identity of her pup. She also smells the placenta and defends it against attack by gulls. Disturbance by gulls, neighbouring seals and human intrusion may lead to the cow failing to establish a bond with the pup and consequently abandoning it.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1975.tb05978.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

The Bontebok is a rare, medium‐sized antelope (males weigh 68–86 kg and females about 56 kg) which is restricted in range to the coastal plain of the south western Cape district of South Africa. The largest herd in existence, consisting of about 250 animals, was studied for 15 months in the Bontebok National Park. Mating is seasonal, occurring in January to March. Females are in oestrus for only about 24 hours and will consort with any male during this time but due to the strongly territorial social system will often be restricted to the territory of a single male. Copulation is repeated many times during the oestrus period and is similar to that described for other members of the Bovidae.The social structure consists of territorial males, very small nursery herds of females and young and a bachelor herd of up to 100 males of all ages. Calving is also seasonal and one birth was witnessed. Females remain with the herd during parturition. There is no lying out behaviour and calves follow their mothers from birth. Calves spent 80–90% of their time lying down for the first two weeks of their life and suckle every one to two hours. Calves less than five days old suckle for significantly longer than older calves.SummaryMating and parturition in Bontebok are strongly seasonal and gestation is about eight months. Most adult females with their young spend their time grazing on the territory of a territorial male in small nursery herds. The male pays attention to all females on his territory and addresses his courtship display to each of his females frequently at all seasons of the year. A female comes into oestrus for about 24 hours and will copulate many times with any male during this period though often she may remain on the territory of a single male. The male and the oestrus female may remain slightly apart from the other females in the group during the period of her oestrus. Copulation is very brief and is similar to other bovids, consisting of a single ejaculatory thrust. There is a marked lack of precopulatory or postcopulatory displays by the male and copulation is preceded only by the normal courtship display or by no display at all. Normally there are bouts of sexual activity involving many unsuccessful mountings and a few successful copulations interspersed with longer periods of other activities (e.g. grazing). The territorial system ensures that other males do not interfere with mating.The female calves in the herd and the calf runs with the mother from birth. There is no lying out behaviour. The females eats the foetal membranes but not the placenta which is dropped 4–6 hours later. Calves spend 80–90% of their day lying down during the first two weeks of life but by seven weeks spend 40% of the day grazing. Calves in the age bracket 6–11 days have a total suckling time during the daylight hours of 80–380 seconds. Calves five days old or less suckle for an average 58 seconds per event, while for 6–11 day olds this drops to 24 seconds—statistically a highly significant difference, suggesting a possible critical period for calf survival during its first five days of life. Occasional suckling continues up to the time the calf leaves its mother. Calves of both sexes leave their mothers at the age of about one year. The female pays her offspring little attention after the age of about three weeks and it is up to the calf to stay with its mother. A lost calf utters staccato bleats when looki

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1975.tb05979.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Phthiracamssp. has one pair of coxal glands. Each gland comprises a thin‐walled sacculus which is specialized for the ultrafiltration of the haemolymph and a tubular labyrinth the ultrastructure of which indicates a specialization for the active resorption of material from the lumen.In addition to its digestive function, the alimentary canal of this mite is also involved in excretion. Excretory material accumulates at the haemocoelic surface of the gut wall and, after endocytosis, passes through the cytoplasm of the cells as discrete bodies which appear in the faecal pellet.The faecal pellet is covered with a peritrophic layer 250–500 nm thick which has no discernible structure and disintegrates in wa

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1975.tb05980.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

The ultrastructure of the metachromatic cells is described. The secretory globules arising from the polarized Golgi apparatus do not show taxonomic variation as do those of the orthochromatic mucous cells.The globular material is not uniform, three main variations being described and interpreted as a reflection of differing hydration states. Gradations and coexistence of more than one form within a cell or single globule occur but, in general, the majority of globules within a cell present the same ultrastructural pattern and size.A relationship exists between the globule size and the three main ultrastructural expressions of the mucus, a fourth variation occurring in cells with very large globules, and a correlation is described between the globule size and the state of the granular endoplasmic reticulum and Golgi apparatus. As a cell ages it gives rise to larger globules containing material of a different hydration level. Young replacement cells are described and their microanatomical differences detailed.The fibrous nature of the mucus is the same as that forming the supracuticular mucoid coat and similar to the acid mucus described in other annelids and other animal groups. Such similarities support the idea of a generalised function and it is suggested that the metachromatic mucus provides the medium through which the respiratory exchanges occur. The necessity for constant secretion leads to speculation concerning the life‐span of the metachromatic mucous cell.SummaryThe metachromatic mucous cells of 11 British lumbricids, from six genera, are characterized by the fibrous substructure of the secretory globules lying within the secretory area. Ultrastructurally the globule material does not show species variation as does the orthochromatic mucus but, nevertheless, is not consistently uniform in appearance. Variations are recorded between cells within a section, between globules within a cell and even within areas of an individual globule.Three main types of variation are described: finely fibrous, the fibrils exhibiting a random arrangement; stranded, where strands of greater electron density are frequently disposed parallel to one another; densely whorled, where the material assumes an exaggerated pattern. Since gradations between these categories exist and more than one form can be present within a cell or even a single globule, it is presumed that the variations are reflecting differing hydration states of the secretory product. In general, the majority of globules within a cell present the same ultrastructural form and size.The globules arise from the mature face of the basally situated, polarized Golgi apparatus and are extruded from the cell through the apical pore which has no occlusor organelles, though mucous pore microvilli are present.A correlation exists between the size of the globules and the fine structural appearance of the secretory material. The densely whorled form occurs only in globules smaller than 0.9 μm; the stranded type in medium sized globules 0.9 μm‐1.3 μm; the finely fibrous variation is only found in cells where the globule size exceeds 1.5 μm but is less than 2 μm. Occasionally cells occur containing very large globules, in excess of 2 μm; and here the secretory material is eccentrically condensed within the globule limit in species other thanD. hibernica.This species presented a substructure, within the very large globules, consisting of a finely fibrous matrix in which there were several electron dense areas and for which no taxonomic or eco‐physiological explanation can be advanced at present.A further correlation is apparent between the globule size and the state of the basally situated secretory apparatus. Cells with small or medium sized globules possess an active granular endoplasmic reticulum, the cisternae of which are filled with medium electron dense material. In those cells with large globules the rough endoplasmic reticulum is frequently bloated, distorted and invariably empty. In cells with very large globules the Golgi system also appears disorganised and the nucleus lacks contrast and shows a distended perinuclear space. Such cells are regarded as being senescent and it is suggested that as a secretory cell ages its ultrastructure alters and the secretory apparatus gives rise to large globules of material of a differing hydration level.Young replacement cells are described and these differ from the normal metachromatic cell in having a nucleus at mid‐epithelial level and granular endoplasmic reticulum and Golgi apparatus not restricted to the basal area of the cell.The fibrous ultrastructural nature of the metachromatic mucus is similar to that forming the supracuticular mucoid coat trapped by the epicuticular projections. It also accords well with descriptions of acid mucus in other annelids and other animal groups. A very striking similarity exists between the present results and those for a histochemically comparable mucus in a turbellarian platyhelminth where globule size and ultrastructural variation has been described.Such comparisons support the idea that the metachromatic mucus has a generalized function and its presence covering the cuticle, combined with blood capillary loops extending to within 1 μm of the cuticle, leads to the suggestion that it is the metachromatic mucus in lumbricids which provides the medium through which the primary gaseous exchanges take place. In providing such a constant respiratory surface, the metachromatic mucous cells are presumably permanently active during their life‐span which might therefore be expected to be shorter than that of a less permanently secretory cell type. The presence or both young and ageing metachromatic cells within the tissue pieces, such stages not being observed for the other secretory cell types, would appear to support s

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1975.tb05981.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

The sounds produced in the laboratory by four species of Australian hopping mice (Notomys alexis, N. cervinus, N. mitchelliiandN. fuscus) were investigated using a tape recorder and Kay Sound Spectrograph.All four species had the same basic repertoire of eight more or less discrete vocalizations.No vocalizations were associated with threat, or fighting. Calls given in the nest by suckling young are well developed and the intensity of such calls appears to mirror the general motivational state of the caller. It is suggested that these calls may act to maintain maternal behaviour in the mother.SummaryThe four species of hopping mouse studied,N. alexis, N. cervinus, N. fuscusandN. mitchellii, were found to have a basic repertoire of eight more or less discrete vocalizations: three in the young—the calls produced in the nest, ultrasonic pipping given when removed from the nest and a high intensity (pain) squeal—and five in the adult—a low intensity pip given during mutual grooming, a high intensity (pain) squeal, a medium intensity squeak given when “annoyed”, twittering given during aggressive chases and ultrasonic pipping given during non‐aggressive encounters. The calls of the different species varied in structure and in pitch. No vocalizations were associated with threat or fighting. Calls given in the nest by suckling young are well developed and the intensity of such calls appears to mirror the general motivational state of the caller. It is suggested that these calls may act to maintain maternal behaviour in

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1975.tb05982.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Force‐platform records and films of kangaroos and a wallaby hopping have been analysed to obtain data about the energetics of hopping and about the stresses which act in muscles, tendons and the tibia. The quantitative anatomical data required for the analysis have been obtained from X‐radiographs and dissections. It is shown that fluctuations of potential energy and external kinetic energy account for most of the energy cost of hopping; fluctuations of internal kinetic energy are relatively unimportant. Evidence is presented that large savings of energy are effected by elastic storage of energy in the gastrocnemius and plantaris tendons. The elastic mechanism is particularly effective at high speeds and seems to account for the observation of Dawson&Taylor (1973) that oxygen consumption is more or less constant over the whole range of hopping speeds. A mathematical model of hopping is presented. The stresses which occur in hopping are discussed.SummaryForce platform records and films have been made of kangaroos and a wallaby hopping.The maximum forces exerted on the ground were about six times body weight. The force exerted on the ground changes direction, throughout the period when the feet are on the ground, so that it is always more or less in line with the centre of mass. Consequently the animal decelerates a little and then accelerates again, during the contact phase.The fluctuations of potential energy which occur in each hop are slightly smaller at high speeds than at low ones. Fluctuations of external kinetic energy increase with speed and account for most of the energy cost of hopping at high speeds. Fluctuations of internal kinetic energy (due to acceleration and deceleration of the limbs) are relatively small. While the feet are on the ground the extensor muscles of the hip do positive work, those of the knee negative work and those of the ankle negative work followed by positive work. The energy cost of hopping is reduced substantially by elastic storage of energy in the Achilles tendon. In the case of a wallaby hopping at moderate speed the calculated saving was 40%. The maximum stresses developed in leg muscles, tendons and the tibia have been calculated and are discussed in relation to the known properties of muscle, tendon and bone. The trunk pitches as the animal hops because the two legs swing forwards and back simultaneously. Appropriate tail movements reduce, but do not eliminate, this effect. A mathematical theory of hopping is presented and used to investigate the merits of different hopping techniques.Dawson&Taylor's (1973) discovery that the rate of oxygen consumption of kangaroos decreases a little, as hopping speed increases, is probably to be explained by the increased role of elastic storage of energy at high spe

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1975.tb05983.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY