摘要:

Observations of reproduction in four gazelle populations in the semi–arid and arid habitats of Israel during three years have revealed intra– and interspecific differences. In the eastern Lower Galilee of northern Israel, female Mountain gazelles(Gazella gazella gazella)reproduce during every month of the year, conceive first at six months of age and exercise long parental care. Females of a population 80 km to the north (Upper Galilee) maintain a seasonal reproductive pattern, conceive first at 18 months of age and have a short parental care period. The latter pattern is similar to the Dorcas gazelle(Gazella dorcas)females of the southern Negev Desert. Interspecific similarities in reproduction of these two populations is attributed to the lack of free water during lactation in both environments where females rely on water available in plant tissue only. The importance of the daily accessibility to water during lactation in female gazelles is discussed. It is suggested that the timing of births and the ability of female gazelles to conceive while lactating are not species‐specific characteristics but simply a matter of short‐term adaptation to changing environmental conditions common understanding today that animal reproductive strategies are a function of prevailing environmental con

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb02808.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The shell of the Common dog‐whelk(Nucella lapillus(L.)) is white and unbanded at most places around the British Isles. However, high frequencies of banding occur on the Buchan coast, around Anglesey and the Menai Straits, on the Cower Peninsula, around the Devon–Somerset border in the Bristol Channel, and especially on the north Cornish coast (reaching a peak between Newquay and Padstow). The frequency of banding is significantly less in older than younger whelks in the same locality, and this change is uncorrelated with the selection against shell shape variation that takes place on exposed shores. It is concluded that banding is a pleiotropic manifestation of physiological variation, and that a study of such variation in different morphs could indicate the importance of different physiological stresses at different stages of the life history ofN. lapil

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb02809.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Oogenesis is compared in two cheilostome bryozoans with contrasting reproductive strategies. from southern Britain:Chartella papyracea(Ellis&Solander) is a non–placental ovicellate brooder, whereasBugula flabellata(Thompson in Gray) is a placental brooder. The ovarian cycles are similar, and each oocyte develops in tandem with a single nurse cell. Eggs of both species are telolecithal, However, those ofB. flabellataare less than 20% the volume of those of the other species, and there are considerable differences in the ultra‐structure of oogenesis. In both cases, spermatogenesis has the typical bryozoan pattern. Precocious insemination of the oocyte occurs in both spec

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb02810.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Recordings of maximum running speeds and maximum horizontal pulling (= pushing) forces have been obtained for 72 species of cursorial and fossorial ground beetles (Carabidae: Coleoptera) belonging to 19 tribes and 12 supertribes. Fore leg, pro‐ and meso‐femoral and tibial and mid leg measurements have also been made and all these parameters have been correlated with body lengths. It was found that those species (mainly Carabinae group I, i.e. Nebriini, Notiophilini, Loricerini, Elaphrini, Cicindelini) with relatively long, slender pro‐and mesofemora, long pro ‐ and mesotibiae and small meso‐coxal articulations were faster runners (i.e. sprinters) but weaker horizontal pushers. In contrast, species (mainly Carabinae group II, i.e. Broscini, Trechini, Pogonini, Bembidiini, Patrobini, Pterostichini, Zabrini, Callistini, Oodini, Licinini, Harpalini) with relatively short, broad pro‐femora, short (slender) mesofemora, short pro– and mesotibiae, and larger meso‐coxal articulations were stronger horizontal pushers but were slower runners. Carabinae group III (Scaritini), however, which have very short, narrow pro‐ and mesofemora, very short pro‐ and mesotibiae, and large meso‐coxal articulations were found to be very strong horizontal pushers but very slow (relatively) runners.The Carabini (including Cychrini), however, resemble Carabinae group II in their running and pushing abilities although their legs are structurally similar to those of Carabinae group I (i.e. relatively long and slender with small meso–coxal articulations). In fact, species of Carabini are fast walkers, their prey is generally slow moving (i.e. slugs, snails and caterpillars) and they hunt in restrictive habitats such as weed patches, meadows or woodland grass which produce a considerable amount of environmental resistance. Most Carabini have a heavy, powerful body which seems to be well adapted to ove

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb02811.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Female Lesser black‐backed gulls, culled from a moorland nesting site in Lancashire for public health reasons, were examined to compare their body condition with the number and quality of eggs that they would lay. The clutch size and stage of the laying cycle of each bird were determined by examining their ovaries. Fat condition was obtained by extraction of the whole carcass with chloroform and an index of protein condition was obtained from the lean dry weight of the flight muscles. Oviduct eggs were analysed for the amounts of fat and protein present in the yolk and albumen.Lesser black‐backed gulls are not fully indeterminate layers. Most females develop only enough enlarged ova to produce the normal clutch of three eggs, with some birds able to lay an additional one or two replacement eggs if necessary. The female's protein reserve, but not her fat reserve, declined during egg formation and was correlated with the total number of eggs she could potentially have laid. Similarly egg quality, as measured by yolk weight and protein content, was correlated with female condition but not her fat reserves. Albumen weight was not correlated with body condition.It is shown that egg production is a demanding process in Lesser black‐backed gulls and breeding success is influenced by the amount of the female's protein reserve both through its effect on egg quality and on her ability to lay replacement eggs if nece

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb02812.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Giant petrels are the chief scavenging seabirds in the Southern Ocean. Quantitatively analysed regurgitations from chicks of bothMacronectes halliandM. giganteusat Bird Island, South Georgia throughout the chick rearing period consisted predominantly of adult Macaroni penguinsEudyptes chrysolophus.Significant quantities of burrowing petrels and krill were taken but the amount varied in different years. Only maleM. hallifed regularly at fur seal carcases. Although 10 species were found in regurgitations, squid were unimportant in the diet. Fish are possibly more important during the winter.Intersexual differences in diet were of greater significance than interspecific ones with males taking more carrion and females more crustaceans. Chicks were fed during both day and night and in both species males received significantly more food than females during the fledging period.M. giganteuschicks received more thanM. halliat all ages.Despite their extensive reliance on carrion both species take a variety of prey and this may be especially important during the winter when penguin and seal carrion is scarce.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb02813.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Around Oxford, breeding pairs of mute swans maintained territories throughout most of the year and these territories varied considerably in potential food availability in the form of aquatic vegetation, bread supplied by the public and pasture for grazing. On territories with abundant aquatic vegetation females laid earlier larger clutches than on those with little aquatic vegetation. Clutches were also larger on territories with a high potential bread supply. In addition, adult females were heavier on territories with a high diversity of aquatic vegetation. However, contrary to expectation, there were no direct relationships between territory quality measures and other aspects of reproductive performance including number of young fledged, egg volume, cygnet weight or size, or adult male weight. Instead, the number of young fledged was related to clutch size; egg volume was related to laying date; and cygnet weight was related to age and egg volume. Adult male weight was positively related to age.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb02814.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Two new taxa,Falklandoglenes spinosagen. nov.and sp.nov.andBeauchenia striatagen.nov. and sp.nov., are described from Beauchêne Island, the most remote island in the Falkland Islands archipelago. Both species are in subfamily Mynogleninae, previously thought to be confined to Central Africa and to New Zealand and its neighbouring subantarctic islands. Both species show intermediate characters between the Mynogleninae and the remainder of the Linyphiidae, and hence they throw some light on the phylogeny of this large, complex, world–wide family of spide

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb02815.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The mating system of the bumblebeesBombus nevadensisandB. griseicollisinvolves apparent territorial defence of perch sites near or within visually conspicuous trees. Non–contact chases between perch owners and intruders are rare inB. nevadensisand more common inB. griseicollis.The perches ofB. nevadensisare in open areas whereas those ofB. griseicoilisare within trees or in sites shaded by trees. The same locations may be occupied on 2 different years. Individual males may return to favoured perches over periods ranging from 2 to 24 days. Males of both species scent–mark spots near their perches early in the morning and then scan visually for passing females for as much as 7–8 h daily. The landmark–based mating system of these bumblebees is similar to that of some other insects and closely resembles the pure dominance (lek) mating system of certain vertebrates. Some hypotheses for the evolution of diversity in male mating tactics among bumblebee species are pr

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb02816.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

A collection of 55 spiders, which was made on Beauchêne Island, Falkland Islands archipelago, in December 1980, contains seven species. Three of these are known from the main body of the Falkland Islands, one is a new subspecies of a species previously known from Patagonia and Tierra del Fuego, and the remaining three are endemic to Beauchêne Island. New taxa described areAuximus fuegianus bransfieldinssp.andEmmenomma beauchenicumn.s

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1983.tb02817.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY