ISSN:0305-1838    

DOI:10.1111/j.1365-2907.1995.tb00431.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTThe fossil record of elephant‐shrews, confined to Africa, goes back to the Eocene, but only three pre‐Miocene genera have been described. The two existing subfamilies, Rhynchocyoninae and Macroscelidinae, were clearly distinct in the Miocene and must have diverged much earlier, but their relationships with the Eocene Herodotinae(Chambius, Herodotius)and the OligoceneMetoldobotesare unclear. The Herodotinae have primitive characters which seem to link them with hyopsodontid condylarths. The Rhynchocyoninae have undergone only minor change since the Early Miocene. On the other hand, the Macroscelidinae, which appear in the record only in the Middle Miocene, diversified to produce at least five species in South Africa in the Pliocene. The Early Miocene Myohyracinae appear to be the sister‐group of the Macroscelidinae, with the dentition specialized for a herbivorous or seed‐eating diet. The origin of Macroscelididae is uncertain: some shared cranial characters suggest a common origin with anagalids, lagomorphs and rodents, but the dentition and eye‐lens proteins suggest condylarth rela

ISSN:0305-1838    

DOI:10.1111/j.1365-2907.1995.tb00432.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTRelationships amongst the 12 species of Macroscelidinae were reviewed by Corbet&Hanks (1968) using a purely phenetic approach. The same data base has been reassessed from a cladistic point of view. However, the polarity of very few character‐series can be assessed with any confidence. A ‘most‐probable’ cladogram is presented based upon the few characters for which polarity seems most convincing, and some alternatives are discussed. The same generic classification is supported but changes are suggested to the branching pattern withinEleph

ISSN:0305-1838    

DOI:10.1111/j.1365-2907.1995.tb00433.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTThe Four‐toed Elephant‐ShrewPetrodromus tetradactylusis one of the most widely distributed elephant‐shrew species, ranging from Kenya to South Africa, while the Golden‐rumped Elephant ShrewRhynchocyon chrysopygushas a limited distribution, being found only on the north Kenya coast. This paper compares the behaviour and ecology of the two species in Arabukc‐Sokoke Forest, Kenya. Compared with Four‐toed Elephant‐Shrews, Golden‐rumped Elephant‐Shrews have larger home ranges and maintain lower densities, as predicted from their greater body size. Both species prefer areas with dense vegetation cover, avoiding open areas, but the Four‐toed ElephantShrew shows a greater preference for dense thicket areas. Territory size was inversely correlated with dry‐season spider abundance in Golden‐rumped Elephant‐Shrews, and with dry‐season ant abundance in Four‐toed Elephant‐Shrews. Differences in activity patterns, as well as body size, may contribute to niche separation between the two species. Both species appear to be monogamous, with males and females defending overlapping territories. Male Golden‐rumped Elephant‐Shrews range over slightly larger areas than females, and are more likely to trespass into neighbouring territories. The less specific habitat requirements of Four‐toed Elephant‐Shrews and their higher densities are probably the two most important factors resul

ISSN:0305-1838    

DOI:10.1111/j.1365-2907.1995.tb00434.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTElephant‐shrews from sub‐Saharan Africa are infested by a large variety of arthropod parasites including ticks, mites, fleas, lice and the larvae of a calliphorid fly. Lists of the ectoparasites recorded from these animals are presented. Of particular importance are the ixodid ticks infesting elephantshrews, as several of these can cause toxicosis, particularly paralysis in domestic animals, while others serve as important vectors of disease. Twenty‐seven ixodid tick species belonging to six genera recorded from elephant‐shrews are listed. Both host‐and tick‐dependent factors must be examined in order to determine the ecology of ticks infesting elephant‐shrews and their relationship to disease in domestic and

ISSN:0305-1838    

DOI:10.1111/j.1365-2907.1995.tb00435.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTElephant‐shrews were classified as Insectivora and were traditionally considered to be insectivorous, although ancestral forms were herbivorous. Despite the presence of a functional caecum, many authors still describe elephant‐shrews as insectivorous. Three data sets, totalling 143 samples, of the Round‐eared Elephant‐ShrewMacroscelides proboscideusdiet from the semi‐arid Karoo, South Africa, were analysed. Results indicate that this species is largely insectivorous, although plant matter makes up almost 45% of the diet by volume. Diet varies seasonally, with the intake of herbage peaking in winter, when herbage may comprise up to 97% of the diet The contribution of insects to the diet was not related to either insect availability (as indexed by pit‐trapping) or body condition, suggesting that Round‐eared Elephant‐Shrews may be true omnivores, selecting a diet of both insects and herbage. The relatively long large intestine of this species of elephant‐shrew may not be related to the water requirements, but may be a plesiomorphic character that has been retained as a consequence of the higher degree of omnivory displayed by Round‐eared Elephant‐Shrews, which appear to consume more plant matter than the

ISSN:0305-1838    

DOI:10.1111/j.1365-2907.1995.tb00436.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTField expeditions between 1986 and 1989 yielded information about the distribution of macroscelids in Tanzania. The rareElephantulus brachyrhynchuswas captured in a natural habitat complex ofmiombowoodland,Combretumsavanna and grassland in Dakawa, Tanzania. Basic ecological data for this species were obtained from 46 animals in a removal‐trapping study and 58 in a live‐trapping study.Sex ratio was near to parity. There was no evidence of a restricted reproductive period, although pregnancy incidence was higher around January‐February. Littersin uterocomprised one or two embryos.E. brachyrhynchushad a preference for the transitionalCombretumsavanna. Stomach contents analysis showed a remarkably high proportion of green plant material in the

ISSN:0305-1838    

DOI:10.1111/j.1365-2907.1995.tb00437.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTThe reproductive ecology ofElephantulus brachyrhynchuswas studied in an area of mixed woodland in the Scngwa Wildlife Research Area, Zimbabwe (18d̀10'S, 28d̀10'E). The year may be divided into three seasons: a cool dry season from mid‐May to mid‐August, a hot dry season from September to November, and a warm wet season from December to April. No seasonal changes were observed in body mass and male reproductive activity. Reproduction occurred throughout the year, but conceptions and litter size were significantly reduced during the cool season. The average litter size of 51 pregnancies was 1.6 (SD 0.49). Adult females had the capacity to produce five to six litters each year for a total annual production of 8.3 young per female.Information on the ecology and reproductive biology of other members of the genus was reviewed to determine latitudinal trends in various life‐history parameters.The pregnancy rate and litter size are not influenced by rainfall and exhibit no seasonal variation close to the equator. At intermediate latitudes (15–20d̀) both parameters are reduced during the cooler period of the year, and at higher latitudes breeding ceases during die period of declining photoperiod. Thus, most young are produced during the warm season when insects are likely to be most available. Litter size increases with latitude, particularly above 15d̀. This increase does not totally compensate for the reduced period of breeding at higher latitudes and so the annual production of young per female is reduced at the northern and southern limits of the range of the genus.There is a particular need to study the general habits of species living at higher latitudes to assess how they adapt during the cold wi

ISSN:0305-1838    

DOI:10.1111/j.1365-2907.1995.tb00438.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTThe metabolic rates of elephant‐shrews are typical of eutherian mammals and follow allometric relationships. They do not exhibit ‘primitive’ characteristics in relation to thermal biology as shown by other insectivores, and their reduced metabolic rates are interpreted as adaptive responses to habitat variables. Stable body temperatures are maintained over a wide range of environmental extremes. Hyperthermia is prevented by evaporative water loss and peripheral vasodilation, whereas hypothermia is probably more widespread than current data suggest.Elephantulus rozetifrom the Atlas Mountains of North Africa has been shown to exhibit spontaneous daily torpor. Although the metabolic rates of macroscelids approximate those of tupaiids, they differ in maintaining a high stable body temperature below the thermoneutral zone.The ecophysiology of the species comprising the three genera studied are different.Petrodromus (tetradactylus)maintains a relatively low body temperature and metabolic rate, but has the lowest relative evaporative water loss and the highest absolute thermal conductance. These characteristics are correlated with a thermally stable but warm, humid environment, and are not explained by taxonomy. The thermal biology and metabolism of species of the other two genera,MacroscelidesandElephantulus, are interpreted as adaptations to thermally variable, arid environments. Although physiologically well adapted, the thermal and metabolic strategy ofMacroscelides (proboscideus)is greatly influenced by its nocturnal behaviour and use of a burrow. The body temperatures and metabolic rates of Elephantulus species are markedly similar, and evaporative water loss varies with water availability in their respective habitats. Species differences are discussed in relation to habitat, behaviour and taxonomy.It is suggested that the common metabolic characteristics of elephant‐shrews were evolved in a stem ancestor, whereas adaptive characters include physiological and behavioural responses to control evaporative water loss and thermal conductance. The metabolic strategy of elephantshrews contributes to their ecological and evolutionary

ISSN:0305-1838    

DOI:10.1111/j.1365-2907.1995.tb00439.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

ABSTRACTThe recommendations and implementation of the IUCN conservation plan for African Insectivora and elephant‐shrews (Nicoll&Rathbun, 1990) are reviewed. Of the 33 species and subspecies of elephant‐shrews, only six forest‐dwelling taxa are threatened. Until additional status data are gathered, assessed, and published no changes in the IUCN threatened categories should be made:Rhynchocyon chrysopygusis ‘vulnerable’;Rhynchocyon petersi petersiandRhynchocyon petersi adersiare ‘rare’; andRhynchocyon cirnei cirnei, Rhynchocyon cirnei hendersoni, andPetrodromus tetradactylus sangiare ‘insufficiently known’. Implementing status surveys that have not been completed, especially for the forms ofR. petersiandP. t. sangi, are a high priority.Rhynchocyon petersiandR. chrysopygusdensities are lower in altered and trapped forests compared with undisturbed forests. Because undisturbed forests in eastern Africa are highly fragmented, small, and disappearing due to human encroachment, it is important to determine the population dynamics ofRhynchocyonspp. that occupy degraded forest habitats, such as plantations, follow agricultural lands, and coastal scrub. In the face of the expanding human population, with its increasing need for land and natural resources,Rhynchocyonpopulations that occur in these degraded habitats may be all that rem

ISSN:0305-1838    

DOI:10.1111/j.1365-2907.1995.tb00440.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY