摘要:

The land snailSphincterochilais represented in Israel by five species that replace one another along a climatic gradient that ranges from the Mediterranean areas receiving up to 1000 mm down to arid areas receiving only 70 mm of rain per year.The resistance to three weeks of desiccation was studied in all five species. Total water loss was lowest in the desert‐dwelling speciesS. zonataand highest in the MediterraneanS. aharoniiand the desert‐dwellingS. prophetarum, while the steppe‐dwellingS. cariosaandS. fimbriatawere intermediate.Sphincterochila zonatahad a significantly thicker epiphragm, the lowest area specific water vapour conductance, the quickest response to desiccation (secretion of epiphragm), and a favourable surface‐to‐volume ratio compared to all other species. The Mediterranean‐type water economy ofS. prophetarum, despite its desert distribution, is related to its being an under‐rock‐dweller while S.zonata, which has the best adaptions to desiccating conditions, thrives in exposed areas. It is concluded that the differences in resistance to desiccation among the five species of one genus correspond to the gross distribution patterns and reflect the abiotic regime and the microhabitat

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02549.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The ontogenetic growth pattern of selected components of the skeleton, muscle mass, and muscle lever arms within the head of the red‐sided garter snake,Thamnophis sirtalis parietalis, were investigated. The results of this analysis appear to indicate an ontogenetic shift from an early emphasis upon prey manipulation to a later emphasis upon striking. The ecological, morphological and phylogenetic evidence for this shift is described and specific testable hypotheses are propose

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02550.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The hock (ankle) joint of horses is bistable: if placed in an intermediate position it springs either to full extension or to strong flexion. We have performed experiments to measure the torques involved and to elucidate the mechanism. The torques were much smaller in hocks of Przewalski's horse (E. ferus) and zebra (E. grevyi) than in those of domestic horses. We suggest that the bistability of the hock is too slight to have much importance for wild horses but may have been enhanced in the breeding of domestic horses by selection for elegance of gait. The elbow joint is also bistable but the stifle (knee) and carpal joints are not.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02551.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

One‐third of territories on South East Island are occupied by trios or groups of communally breeding skuas. Comparisons were made of the reproductive performance of pairs, trios and groups over three (and ten) seasons to assess whether any ‘advantage’–in terms of offspring production–could be demonstrated for communal breeding. Egg size was not significantly different between pairs and trios, or between years. There were no significant differences between the chicks of pairs, trios or groups in growth characteristics and chick condition appeared similarly good. Overall breeding success was generally lower for trios than for pairs. Although chick production per territory was not significantly different between pairs and trios, it was substantially lower on a per‐adult basis. The breeding success of this population is generally high compared to others studied, however, there is no evidence to suggest that skua communal breeding has advantages in terms of offspring

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02552.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Gerhillurus paeba paeba, G. tytonisandPelromyscus collinusinhabit arid areas of southern Africa. Several litters of each species were bred in the laboratory; aspects of maternal behaviour and development of neonates are reported.Pelromyscus collinushas a smaller litter size and the young are less altricial at birth than young ofG. paebaorG. tytonis. Gerhillurus tytonisyoung have the slowest rate of physical and behavioural development, whileP. collinusyoung develop most rapidly. Young ofP. collinusnipple‐cling from birth, but those ofG. paebaandG. tytonisdo not. This dichotomy may be related to phylogeny, mode of locomotion, and/or nesting habit

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02553.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The amount of honeydew collected by the weaver antPolyrhachis simplex(Hymenoptera: Formicidae) was measured when it attended the mealybugTrabutinasp. (Homoptera: Pseudococcidae). Measurements were made in a relatively cool month (March; mean daily minimum and maximum air temperatures while the ants were active were 17 °C and 23 °C, respectively), a warm month (April; 18 °C and 28 °C) and a hot month (May; 20 °C and 35 °C). TheTrabutinasp. were located on a tamarisk tree. No byres were made by the ants aroundTrabutinasp. clusters in March, initial byre stages were noted in April and many byres were found in May. In March, maximum ant activity was at midday, the hottest part of the day, whereas in April and May there were troughs of activity at that time. In May, the trough was more pronounced than in April and activity was high in the early morning while it was low in April. Honeydew fresh matter collected by the ants was significantly negatively correlated with air temperature and positively correlated with relative humidity. Dry matter collected was not significantly correlated with any of these two variables and showed no difference throughout the day or among months. Within months, the least amount of honeydew fresh matter was collected at the highest air temperatures and at the lowest relative humidities and, among months, the least was collected during the hottest month. It was postulated that evaporative water loss of the ants increased with high air temperature and low relative humidity. Activity and honeydew collection by the ants was highest in April. During March, 3372 ants entered the nest daily with 2900 mg dry matter of honeydew, during April, 8157 ants entered daily with 6933 mg and during May, 6207 ants entered daily with 5152 mg. This daily honeydew intake had an energy content of 51 1 kJ, 122.3 kJ and 90.9 kJ in the three months, respectively. EachTrabutinasp. attended by ants excreted 0–51 mg dry matter of honeydew per hour, whereas each unattendedTrabutinasp. excreted 012 mg dry matter per hour.It was concluded thatP. simplexused both behavioural and physiological mechanisms in coping with the environment. During cool months they increased their activity at the hottest part of the day. During hot months they reduced their activity during the hottest part of the day and they either remained in their nests, where the air temperature was lower and relative humidity was higher, or many ants remained in byres protected from much of the solar radiation. Those ants that were active during the hottest part of the day increased their evaporative wat

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02554.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Daily activity of Eurasian otters(Lutra lutra) was recorded along the coast of Shetland, UK, in the summer of 1984. Data of three otters fitted with radio‐transmitters were analysed in detail. Compared to sea otters (Enhydra lutris), these otters spent up to 4.5 times less time per day hunting (12%), but devoted the same time per day to grooming (6%). Hunting bouts (mean 13.7 min) were interrupted by resting bouts (17.0 min) during which the otters groomed (9.1 min) and slept (6.6 min). The duration of the resting bout was significantly correlated (P<0.05) with that of the preceding hunting bout. Also, the time spent grooming was correlated with the encountered underwjter pressure (P<0.05). The functions of resting and grooming probably include reestablishing air in the fur and rapid recovery after diving; also avoiding encrustation of salt on the fur might be importan

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02555.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Biomechanical scaling of long bone joint surface areas was investigated in 13 species of anthropoid primates. It was proposed that joint surface areas should scale with positive allometry with respect to body size in order to maintain relatively constant safety factors for joints in small and large animals and that modifications from the overall pattern of scaling may be expected in the limb joints of species exhibiting specialized locomotor behaviours that radically alter limb loading. Within anthropoids, the brachiating primates, white‐handed gibbons (Hylobates lar) and black‐handed spider monkeys (Ateles geoffroyi), were used to test this hypothesis. Total joint surface areas were found to scale with significant positive allometry in 11 of 12 limb joints. The observed pattern of interspecific allometry supports the hypothesis that weight bearing is a major constraint on the design of joints. This positive interspecific allometry is reflected at the intraspecific level as well, with larger joints of larger species showing significant intraspecific scaling. Suspensory species showed no significant deviations from the overall anthropoid pattern, despite their reduced compressive loading of the limb joints, even after controlling for joint mobility. These results suggest that, while evolutionary changes in locomotor behaviour that produce significant increases in loading of a joint may be accompanied by selection for increased joint surface areas, adoption of locomotor repertoires that reduce limb loading may have no selective effect on joint morphology, and joint design in these cases will reflect the biomechanics of the ancestral locomotor condit

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02556.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Total body water (TBW) and water turnover rate (WTR) were measured in 24 subterranean mole rats comprising four populations, each belonging to a different chromosomal species of theSpalax ehrenbergisuperspecies in Israel. The four species range in different climates: humid‐cool (2n = 52); semiarid‐cool (2n = 54); humid‐warm (2n = 58) and arid‐warm (2n = 60). TBW, as a percentage of body weight, measured by tritiated water (HTO), was 72.4%±4–7 in 2n = 52, significantly (P<005) higher than the similar estimates 61.7%± 7.2, and 59.4%± 5–3, for 2n = 60 and 58, respectively. A comparison of HTO space, as a percentage of TBW, closely approximated TBW, ranging from 97% to 108%. WTR was high, 218.1 and 230.9 ml/kg0‐75/day in the mesic populations of 2n = 58 and 52, respectively. By contrast, WTR estimates were significantlylower, (P<0.001), 150.2 and 148.9 ml/kg0‐75/day in the xeric populations of 2n = 54 and 60, respectively. The biological half‐life time, T1/2, was similar and faster, 32.7 and 27.9 hours in the mesic populations of 2n = 52 and 58, as compared with slower, 47.9 and 40.8 hours in the xeric populations of 2n = 54 and 60, respectively. Urine osmolarity in the most xeric northern Negev steppic population of 2n = 60 (737 ± 45 mmol/kg) was significantly (P<0.001) higher than in the other species.We conclude that adaptive radiation in theSpalax ehrenbergisuperspecies involves speciation in semiarid (2n = 54) and arid (2n = 60) climates by physiological adaptations of kidney water conservation, along with multiple morphological, physiological and behavioural syndromes of climatic adaptations to increasing

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02557.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The abyssal propeamussiidPropeamussiumis well known from studies of shell structure and is believed to be representative of a relict lineage, sister to the group which gave rise to all shallow‐water pectinaceans.From analyses of stomach contents, species ofPropeamussiumhave been reported to be predators. This study confirms this and shows that small meiobenthos or epibenthic planktonic larvae and crustaceans constitute the diet. Prey is thought to be caught by an inrush of water to the mantle cavity and pushed into the mouth with the foot. The stomach is small, secondarily simplified and adapted for the digestion of small creatures. It is convergent with the stomachs of similarly predatory, abyssal anomalodesmatans. Palps are vestigial. The ctenidia are of a new type (B(4)), perhaps derivable from the dimyid ctenidium by the loss of the ascending lamellae of all four demibranchs and the ventral fusion of inner and outer descending lamellae on each side of the body to create a gill where the apices of the filaments are internal. Filter feeding is thus impossible, the ctenidia now wholly subserving a respiratory function.Aspects of shell structure, adductor muscle arrangement and form of the pallial margin suggest thatP. lucidumis a proficient swimmer. It is concluded, however, that prey is not caught during swimming, and that the two activities are mutually incompatible. Probably swimming is used only for escape.Ctenidial structure forges links with the Plicatulacea (Dimyidae, Plicatulidae), shell structure with the Pectinacea (Pectinidae, Spondylidae) and it is concluded that the Propeamussiidae is indeed a relict group with links back to more primitive plicatulaceans and with the modern shallow‐water Pectinacea, but evolving, in the isolation of the abyss, remarkable adaptations for a predatory mode of life. The Propeamussiidae also demonstrate striking convergence with the abyssal predatory Anomalodesm

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1989.tb02558.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY