Journal of Zoology
0952-8369
1469-7998
Mỹ
Cơ quản chủ quản: Wiley-Blackwell , WILEY
Lĩnh vực:
Ecology, Evolution, Behavior and SystematicsAnimal Science and Zoology
Các bài báo tiêu biểu
Living fast and dying young: A comparative analysis of life‐history variation among mammals Recent comparative studies point to the importance of mortality schedules as determinants in the evolution of life‐history characteristics. In this paper, we compare patterns of mortality from natural populations of mammals with a variety of life histories. We find that, after removing the effects of body weight, mortality is the best predictor of variation in life‐history traits. Mammals with high levels of natural mortality tend to mature early and give birth to small offspring in large litters after a short gestation, before and after body size effects are factored out. We examine the way in which life‐history traits relate to juvenile mortality versus adult mortality and find that juvenile mortality is more highly correlated with life‐history traits than is adult mortality. We discuss the necessity of distinguishing between extrinsic sources of mortality (e.g. predation) and mortality caused by intrinsic sources (e.g. costs of reproduction), and the role that ecology might play in the evolution of patterns of mortality and fecundity. We conclude that these results must be explained not simply in the light of the demographic necessity of balancing mortality and fecundity, but as a result of age‐specific costs and benefits of reproduction and parental investment. Detailed comparative studies of mortality patterns in natural populations of mammals offer a promising avenue towards understanding the evolution of life‐history strategies.
Tập 220 Số 3 - Trang 417-437 - 1990
Primates, brains and ecology The paper examines systematic relationships among primates between brain size (relative to body size) and differences in ecology and social system. Marked differences in relative brain size exist between families. These are correlated with inter‐family differences in body size and home range size. Variation in comparative brain size within families is related to diet (folivores have comparatively smaller brains than frugivores), home range size and possibly also to breeding system. The adaptive significance of these relationships is discussed.
Tập 190 Số 3 - Trang 309-323 - 1980
Experiments on whether schooling by their prey affects the hunting behaviour of cephalopods and fish predators The experiments investigated the effects of a school of live prey fish on the hunting behaviour of squid, cuttlefish and pike (ambush predators) and perch (a chasing predator). The hunting behaviour of all species is described, including some previously unrecorded actions. For all species the increasing shoal size from one fish to six, to 20, decreased the success of the predators' attacks per encounter with a prey. This was partly because attacks on larger shoals lasted longer, and fish became increasingly difficult to catch as a hunt went on. However, for some of the species there was a clear effect of the shoals at the start of the hunt. For other species it was less conclusive. The disruptive effect of the shoals was shown to act for the ambush predators by interfering with the “optimal” sequence of an attack and causing avoidance actions together with so‐called irrelevant behaviour. For the perch, shoals seemed to disrupt by forcing the predator continually to switch targets during his pursuit. The artificiality of the experiments is discussed in relation to field observations. The relatively high incidence of avoidance and irrelevant behaviour seems to be an artefact, but the main results are quite compatible with field studies. In nature fish predators may be able to get sufficient food by restricting their attacks to individuals which are conspicuous either by an abnormal appearance or by becoming separated from the school. An individual prey fish no doubt gains a considerable advantage from the school by burying itself in the crowd. Our experiments show that a shoal can provide further protection in hampering the attack of a predator.
Tập 172 Số 4 - Trang 549-569 - 1974
Mechanical properties of various mammalian tendons Dynamic tensile tests have been performed, using physiologically relevant frequencies and stress ranges, on various tendons from the legs and tails of 10 species of mammal. No consistent differences were found between tendons from different species or different anatomical sites. Tangent Young's modulus increases from low values at low stresses to about 1·5 GPa at stresses exceeding 30 MPa. Percentage energy dissipations of 6 to 11% have been measured for different species, but the lower values are probably the most reliable. There is little or no dependence of modulus or energy dissipation on frequency, in the range 0·2–11 Hz. The tensile strength of tendon (at strain rates of the order of 0·05 s−1 ) is at least 100 MPa.
Tập 209 Số 4 - Trang 537-548 - 1986
Behavioural responses of killer whales (<i>Orcinus orca</i>) to whale‐watching boats: opportunistic observations and experimental approaches Abstract Johnstone Strait provides important summer habitat for the northern resident killer whales Orcinus orca of British Columbia. The site is also an active whale‐watching area. A voluntary code of conduct requests that boats do not approach whales closer than 100 m to address perceived, rather than demonstrated, effects of boat traffic on killer whales. The purpose of the study was to test the relevance of this distance guideline. Relationships between boat traffic and whale behaviour were studied in 1995 and 1996 by shore‐based theodolite tracking of 25 identifiable focal animals from the population of 209 whales. Individual killer whales were repeatedly tracked in the absence of boats and during approaches by a 5.2 m motorboat that paralleled each whale at 100 m. In addition, whales were tracked opportunistically, when no effort was made to manipulate boat traffic. Dive times, swim speeds, and surface‐active behaviours such as breaching and spy‐hopping were recorded. On average, male killer whales swam significantly faster than females. Whales responded to experimental approaches by adopting a less predictable path than observed during the preceding, no‐boat period, although males and females used subtly different avoidance tactics. Females responded by swimming faster and increasing the angle between successive dives, whereas males maintained their speed and chose a smooth, but less direct, path. Canonical correlations between whale behaviour and vessel proximity are consistent with these conclusions, which suggest that weakening whale‐watching guidelines, or not enforcing them, would result in higher levels of disturbance. High variability in whale behaviour underscores the importance of large sample size and extensive experimentation when assessing the impacts of human activity on killer whales.
Tập 256 Số 2 - Trang 255-270 - 2002
Does metatarsal/femur ratio predict maximal running speed in cursorial mammals? 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 with caution.
Tập 229 Số 1 - Trang 133-151 - 1993
On the origin of faeces: morphological <i>versus</i> molecular methods for surveying rare carnivores from their scats Abstract Charismatic mammals remain a linchpin in attracting publicity and funds for the conservation of native habitats and organisms. Unfortunately, the same animals are frequently scarce and difficult to survey. For many, confirming their presence through faecal surveys is the only cost‐effective approach. Here we show that, contrary to received opinion, expert naturalists fail reliably to distinguish pine marten Martes martes faeces (‘scats’) from those of foxes Vulpes vulpes . Moreover, their judgement fails completely when the animals and their scats are at their most scarce. This unexpected result from such a well‐studied species has important implications for the monitoring of endangered mammals. We recommend that in the future, a multi‐evidence approach should be adopted to monitor elusive mammals, involving DNA methods, cast hair identification, camera traps, and non‐leading ‘sighting’ questionaires. For national surveys, it may soon become cost‐effective to screen large numbers of samples using microarray technology.
Tập 257 Số 2 - Trang 141-143 - 2002
Ultrasound and mating behaviour in rodents with some observations on other behavioural situations Ultrasounds have been detected during mating behaviour in all 11 species of myomorph rodents in which this behaviour has been observed. The signals produced by each of the species studied are described. In all species except hamsters, these signals appear to be produced by the male. Ultrasounds have also been detected from rodents in other situations such as during and after disturbance and when placed in new surroundings. The possible significance of these ultrasonic signals in the lives of rodents is discussed.
Tập 168 Số 2 - Trang 149-164 - 1972
Continuing wildlife population declines and range contraction in the Mara region of Kenya during 1977–2009
Tập 285 Số 2 - Trang 99-109 - 2011
Variation in the calorific value and total energy content of the lesser sandeel (<i>Ammodytes marinus</i>) and other fish preyed on by seabirds Wet and dry calorific values (energy densities) and total energy content of lesser sandeel Ammodytes marinus , sprat Sprattus sprattus , Atlantic herring Clupea harengus , whiting Merlangius merlangus , saithe Pollachius virens and cod Gadus morhua , were measured. Calorific values varied both within and between species. Larger fish tended to have higher calorific values than small ones, particularly when considered in terms of wet weight, but there was considerable temporal variation. The calorific values and body weights of sandeels larger than 10 cm showed marked seasonal trends and in consequence the total energy content of a sandeel of given length in summer is approximately double the spring value. The calorific values of herring and sprat also varied from month to month but seasonal cycles were less obvious. Whiting varied least. Both calorific values and total energy content of individual sprat were very variable in summer (the spawning season of this species). Because there is so much intraspecific variation, care must be taken when assessing the relative merits (in terms of energy) of different species as prey. The practical difficulties of obtaining reliable data on wet calorific values are discussed and the use of dry calorific values and dry weight/length relationships is recommended.
Tập 224 Số 3 - Trang 501-517 - 1991