摘要:

The ecological genetics of a population of fieldmice at the edge of a deciduous wood was studied over two years using starch‐gel electrophoresis and mark‐recapture techniques. Numbers fluctuated widely and the survival rates indicated a high degree of dispersal away from the grid in summer. In autumn 1974 a large influx of animals occurred when the adjacent fields were harvested. During the following winter significant changes in the phosphoglucomutase genotype frequency were observed, associated with a marked fall in numbers. Winter survival is normally good inApodemus.These results are therefore of some interest.Either differential mortality or differential emigration could be responsible for the genetic changes. The former explanation is preferred in this situation. Fieldmice are known to exploit both field and wood habitats where they meet, and could be subject to differences in selection pressure in the two nic

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb03910.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Glycacarus combinatusgen. andsp. nov. was collected from the nest of the White chinned petrel (Procellaria aequinoctialis) on Possession Island Sub‐Antarctica. It can be distinguished from all other members of the Astigmata by the M‐shaped prodorsal shield and by the fact that it is made up of a complete mixture of the morphological characters which separate the Glycyphagidae from the Acaridae. In order to maintain the present familial structure within the free‐living Astigmata a new family Glycacaridae is proposed. It is suggested that these three families arose from three evolutionary lines which separated from a common ancestor possibly during the Cretaceous period. Ontogenetic development of the body setae is described and a new interpretation of setal homologies relative to different life‐cycle stages is discussed, together with a revised nomenclatural system for the idiosom

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb03911.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The structure of the cochlea has been studied in 26 species of feral rodents from the Sub‐Orders Myomorpha and Caviomorpha. The specimens were all intravitally perfused to obtain good preservation of the internal ear. The following measurements were made on the cochleae: the height and width of the cochlea, the number of half‐turns, the width and thickness of the basilar membrane, the height of the cells of Claudius and the size of the spiral ligament; other special features were also no

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb03912.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The habitat preferences of small rodents were studied by live trapping methods at Wicken Fen, Cambridgeshire, a relict area of East Anglian fenland. The study sites were chosen to cover areas of managed fields, dominated by sedge (Cladium mwiscus) or by litter (grasses with sedges); the adjacent fen carr “bush growth”; and an area of unmanaged sedge.Clethrionomys glareolusis the commonest rodent species, occurring at relatively high densities, and closely associated with sedge growth. It is ubiquitous in unmanaged sedge but in managed sedge and litter field areas there is a marked preference for the field/fen carr transition where sedge growth is not cut. Thick sedge seems to afford the optimum habitat for this species probably because of the three‐dimensional vegetation structure which provides dense ground cover with a natural thatch of dead leaves; this decays only slowly, even in succeeding fen carr. Sedge fields provide a less stable habitat and recolonization of a harvested field byClethrionomysonly began after eight months of sedge regrowth.Micromys minutusare caught only in sedge and litter.Apodemus sylvaticusseem to show no marked habitat preference but there are some data which suggest that highClethrionomysdensities can affectApodemusdistributions locally.Microtus agrestisprefers grassy patches within sedge fields; trap success points tending to be associated with the presence ofCalamagrostis canescens. Microtusavoids fen carr and unmanaged sedge and is generally caught more often in litter fields than in sedge fields; however, this preference seems to disappear at the end of theClethrionomysbreeding season. During flooding,Clethrionomysfound refuge in the dense sedge and sedge/carr transition habitats; prolonged flooding caused a decline in numbers ofClethrionomysand the elimination ofMicrotus, while the distribution ofApodemuswas apparently unaff

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb03913.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Fox size variation, both today over a wide geographic range and during the late quaternary in Israel, was correlated with temperature changes. Competition with the related Asiatic jackal was not considered to have any effect on fox size; the degree of dwarfing of the fox was utilized in a speculative estimate of the Pleistocene—Holocene temperature ris

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb03914.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Light and electron microscopy has shown the alimentary canal ofParanthessiusto be composed of clearly defined foregut, midgut and hindgut regions. The spacious foregut is cuticle‐lined and separated from the midgut by a valve. The midgut epithelium is composed of columnar cells with an apparent secretary/absorptive rôle, and amoeboid cells thought to engulf material from the lumen. The amoeboid cells have large electron‐dense central vacuoles containing carbohydrate‐and protein‐staining material. These cells appear to be sloughed off into the lumen to form part of a faecal pellet. Apart from their digestive rôle the midgut cells store lipid and it is considered possible that they have an osmoregulatory function. The hindgut epithelium cell type, lacks a cuticular layer and is thought to be mainly concerned with absorption. The alimentary canal is surrounded by strands of longitudinal and circul

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb03915.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The burrows of the Red band fish,Cepola rubescensL. are described from casts takenin situusing polyester resin. Observations of behaviour and spatial distribution are presented and the coloration, morphology, age, gonad condition and diet of captured specimens are discussed.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb03916.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The previous multitude of taxa of North Pacific Harbour seals is referable to, at most, three forms: the ice‐inhabiting Larga seal,Phoca vitulina largha; the Insular seal of eastern Asia,P. v. stejnegeri; and the coastal Harbour seal of western North America,P. v. richardsi.In the breeding season,larghaoccurs on the pack ice of the Bering, Okhotsk, Japan, and Po Hai seas as adult pairs with single pup, whereasstejnegeriandrichardsiare associated with coastal and insular habitats, around the perimeter of the North Pacific Ocean from Hokkaido to Baja California (i.e. mostly well away from ice), and occur on land in dense aggregations of less than ten to more than a thousand animals. In general, where the ranges of thelarghaand thestejnegeri‐richardsiforms meet or overlap, their respective breeding seasons are about two months apart, which, together with the social and habitat differences, tends to result in reproductive isolation. Apparently, the young oflarghaare always born with a whitish lanugo, whereas those ofstejnegeriandrichardsiusually shed their lanugo (either whitish or mottled greyish)in uteroand are born with an adult‐like pelage. The adult pelage oflarghaseems always to be pale background with a spattering of small, blackish spots, whereas thatof stejnegeriandrichardsiranges from black with scattered whitish rings (dark phase) to pale with small black spots (light phase). Light phase animals usually differ fromlarghain having some whitish rings on the back. In body and skull size,stejnegeriexceeds the others, but in cranial characters,stejnegeriandrichardsiseem very similar and to differ mutually fromlarghain all respects. They also differ fromlarghain having abbreviated stylohyals, not connected to the bulla. The complex nomenclatural history of each taxon is reviewed, and the namelarghaPallas, 1811 is retained for the ice‐inhabiting form. For the insular form,stejnegeriAllen, 1902 has priority, and for the American coastal form,richardsi(Gray, 1864).Larghaoccurs as eight geographical populations that are morphologically alike, suggesting that they have been separated for a relatively short period in geologic time. Thestejnegeri‐richardsicomplex, conversely, shows a much greater degree of regional differentiation, as indicated by the frequency of occurrence of dark and light colour phases, but appears to be all of one polytypic, trans‐Pacific form, which is more similar to the North Atlantic Harbour seals than islargha.Althoughlarghahas usually been regarded as a subspecies ofP. vitulina, it seems advisable on the basis of this review to accord it sp

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb03917.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1977.tb03918.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY