摘要:

The cattle of Doñana (139 individuals in four social groups in 1989) have lived under free‐ranging conditions for centuries. Their ranging behaviour was analysed during a three‐year period. A total of 17,603 locations corresponding to 247 different animals allowed both for the estimation of global and seasonal home ranges of individuals and social groups and for the comparison of movement patterns. Cattle ranging behaviour was not affected by human interference, and was shown to be regulated by a complex interaction of environment, individual and social factors. Habitat structure and seasonal fluctuations in abundance and distribution of resources determined general patterns of ranging behaviour: the greater the concentration of resources, the smaller the home ranges of individuals and social groups. These patterns were modified at an individual level by the sex of the animal and its reproductive status if male. Social influences on ranging behaviour were important because these implied the segregation of home ranges among dominant bulls and among social groups. As a result, there was a great variability in space use and home‐range beh

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb02718.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

In this paper, we present an analysis of the consequences of increasing density, over a period of nine years (from 1980 to 1988), on the dynamics, and the social and spatial organization of a forest roe deer population. Hunting of this population ceased in 1979, after which time there was a significant increase in population density, with three distinct periods easily identified: 1980–1983 (PI), immediately following cessation of hunting, characterized by a relatively low density (d = 5–7 animals/100 ha), 1984–1985 (P2), a period of rapid population growth, and 1986–88 (P3), a period of high density (d = 25 animals/100 ha). During PI, the population was irregularly distributed across the study site but, as density increased, distribution became more uniform, and eventually covered the whole of the available area. Home‐range structure and shape remained unchanged from PI to P3 but, by the end of the study, average range size was 30% lower for adult males only, and the period prior to subadult males, but not females, establishing a permanent home range had increased fromc.18 month toc.30 months. Winter group size increased overall from PI to P3 with, for the first time, observations of groups of five or more animals and a reduction in the frequency of observations of solitary females, with does more commonly observed in pairs or small groups; the proportion of solitary males, however, did not change between the two periods. The mean number of kids per female declined significantly from PI to P3 and body weights recorded for juveniles of both sexes and for adult males were also significantly lower during the period of relatively high density (P3). However, for adult females, absolutely no body weight change was observed. This divergence between the sexes of response to increasing density is

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb02719.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

The endemic Seychelles treefrog,Tachycnemis seychellensis(Duméril&Bibron), is restricted to four of the granitic islands of the Seychelles: La Digue, Mahe, Praslin and Silhouette.Megalixalus infrarufusGunther 1869 is a junior synonym ofEucnemis(Tachycnemis)seychellensisDumeril Bibron, 1841. Significant variation in colour and morphometric characteristics exists within and between island populations. The patterns of geographic variation revealed support the hypothesis that the distribution ofTachycnemis seychellensisin the granitic Seychelles reflects vicariance through fragmentation of the Seychelles Microcontinent 10,000 years B. P. by marine transgression. However, the possibility of low rates of postfragmentation dispersal between islands cannot be ruled out. The close relationship of the nearby Mahe and Silhouette populations probably reflects prefragmentation gene flow over relatively short distances and postfragmentation stasis due to large population size and similar environments. The small body size and colour similarities of the Praslin and La Digue populations may result from prefragmentation gene flow between these close populations, but the relatively great differences in morphometric traits suggest rapid divergence in isolation perhaps as a result of genetic drift and strong selection. It is argued that the four island populations represent a single species and that subspecies should not be named

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb02720.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Twenty‐eight generations of mass selection for an unstable micropterism (short wings) in the red firebug,Pyrrhocoris apterus(L.), resulted in anunstable micropterous(ump) strain with a high frequency of micropterous individuals. The strain, segregating individuals with enormously reduced wings, is polymorphic for mosaic pigmentation in the epidermis. Micropterous individuals, both symmetric and asymmetric, appear predominantly among pigmentation mosaic (umpmo) forms. Individuals with a normal, nonmosaic epidermis (umpwt) are rarely micropterous. The reproductive capacity of micropterousumpmofemales is strongly reduced. It is suggested that pigmentation mosaicism and unstable micropterism may have a common or linked genetic basis. A new mode of wing length regulation is suggested, engaged in conspicuous destabilization ofumpwings and consisting presumably of transpositions of mobile genetic element

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb02721.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Golden moles (Chrysochloridae) are fossorial mammals known to have unusual mallei. The aim of this study was to describe and quantify aspects of the auditory morphology of golden moles in order to determine their systematic and functional implications. Observations were made on skeletal material as well as histological sections. The results of this study do not support the separation of the genusCalcochlorisfromAmblysomus. It was found that the morphology shared by all the studied genera is indicative of specialization for hearing low frequency sound. The tympanic membrane to stapes footplate ratios, ossicular lever arm ratios and incudomallear joint morphology suggest low frequency specializations in genera with small mallear heads and high frequency specializations in genera with large mallear heads. However, the size and degree of trabeculation of the tympanic cavity are not consistent with this result. It is proposed that all golden moles are low frequency hearers with differences in their range of sensitivity according to how much time they spend foraging above ground.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb02722.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

This paper is dedicated to the late Nigel Bonner, who as Head of the Life Sciences Division at British Antarctic Survey, encouraged and supported this research with his characteristic enthusiasm.The cryptostigmatid miteAlaskozetes antarcticus(Michael) is a dominant member of many terrestrial communities in the maritime Antarctic, where it survives extreme temperatures, short cold summers, numerous freeze‐thaw cycles, desiccating conditions and a limited season for growth and reproduction. However, examination of features of its biology, from morphology, through life‐history strategy to physiology, indicate very little specialization to the Antarctic environment.Alaskozetes antarcticusis a herbivore/detritivore, typical of the Cryptostigmata in general, with low feeding and growth rates, long life span and low reproductive output. Physiological specializations exist in the form of low enzyme activation energies and elevated metabolic rates at low temperatures when compared with temperate species, and associated low optimum temperatures for activity, feeding and growth. Growth rates comparable with temperate species are achieved in the field, with an extended life cycle of five years or more as a result of the short growing season, and the ability of all life stages to overwinter equally successfully. Overwintering survival, involving supercooling enhanced by the use of antifreezes such as glycerol, although initially described in Antarctic species, is now known to be characteristic of many temperate relatives, so it is not a specific adaptation to the polar environment. The obvious success ofA. antarcticusin maritime Antarctic terrestrial environments must be attributed to a combination of several features characteristic of the Cryptostigmata in general, rather than to specific polar adaptati

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb02723.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Small mammals were found on set‐aside and surrounding farmland. Wood mice showed a different pattern of demography at two sites, with higher densities, greater survival, heavier weights and longer breeding seasons at Aldroughty than at Newburgh. These differences were thought to be due to a difference in habitat productivity at the two sites. Field voles showed less of a difference in population dynamics between the two sites, and both species of vole maintained populations at low densitie

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb02724.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

The ecology of four species of Psephenidae (water penny beetles) was investigated in Tai Po Kau Forest Stream (TPKFS), New Territories, Hong Kong, over a two‐year period. Quantitative benthic samples were taken from different microhabitats in the stream on 47 occasions and, in combination with light‐trap catches of adult beetles, were used as a basis for investigating life‐history patterns and estimating secondary production. Total psephenid annual production over the period 1977–79 was 930–5 mg AFDW (ash‐free dry weight) 0.5 m‐2, but was more than twice as high in 1977–78 (1381–6mg AFDW 0.5m‐2) than in 1978–79 (562.6mg AFDW 0.5m‐2).Sinopsephenus chinensisandEubrianaxsp. were the most abundant psephenids in TPKFS, but the largerS. chinensiscontributed most to total psephenid secondary production.Eubrianaxsp. made the second largest contribution to production, while the contribution of the two remaining species (Psephenoidessp. andMataeopsephussp.) was minor.Eubrianaxsp. production was generally constant between years, but production (and population densities) of the other three psephenids declined in 1978–79.Sinopsephenus chinensiswas clearly bivoltine in TPKFS, butEubrianaxsp. andPsephenoidessp. showed asynchronous growth and almost continuous recruitment. Accurate estimates of production: biomass ratio (P: B) ratio were possible forS. chinensisonly, and varied between 12.8 and 19.4 over the two years of the study.Eubrianaxsp. and (especially)S. chinensiswere most abundant in midstream microhabitats butPsephenoidessp. was more numerous close to the stream banks.Mataeopsephussp. was relatively rare and lacked an obvious microdistribution pattern. Multivariate statistics (principal components analysis followed by multiple regression) were used to investigate the relationship between psephenid densities in each benthic sample and the sediment characteristics, detrital standing stocks and algal biomass in the environment where the sample was taken. The analysis revealed that psephenid microdistribution was influenced by sediment grain‐size characteristics rather than by algae or detritus, but the proportion of variation in the abundance of psephenid species accounted for by sediment cha

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb02725.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Postural and kinematic characteristics of the drinking behaviour in the diamondback turtle,Malaclemys terrapin(Latreille) were investigated by video and high‐speed filming experiments. Head, jaw and throat movements in drinking cycles are described. Postures of neck and head were compared for three water depths (2, 10 and 30 mm). Water expulsion, occurring after the turtle was disturbed, is also kinematically described. Finally, a drinking mechanism in the turtle is propose

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb02726.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

The lesser pouched rat,Beamys hindeiThomas 1909, is one of Africa's rarest and least known rodents, recorded only from a few localities in Kenya and Tanzania. The results of this study show thatB. hindeiis more widely distributed than previously thought and occurs at high densities in suitable habitat. It breeds throughout the year, but maintains relatively constant population densities as recruitment rates are low. On account of its ability to cache food, it is well adapted to seasonally dry forests where food is in short supply for part of the year. The need for suitable soil in which to construct its burrows and dense vegetation cover may partly account for its patchy distribution. Morphological data collected during this study provide no evidence for separatingB. hindeifromB. majorand suggest that the differences previously recorded between the two forms may be actually due to clinal variation in size from north to south.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb02727.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY