摘要:

Brookesiadwarf chameleons, endemic to Madagascar, were surveyed at the following localities in northern Madagascar (north of 16°S): Montagne d'Ambre, Ankarana, Manongarivo, Tsaratanana, Marojejy and Masoala. A total of 15 species occur in this region. Six new species are described and five new synonyms are identified. The genusBrookesia, the most speciose chamaeleontid genus in Madagascar, contains 23 species.Almost all the northernBrookesiaspecies are restricted to rainforest and occupy a relatively narrow elevational range. Although the northern rainforests represent just one‐third of the total rainforest and about 5% of the total island area, 65% of theBrookesiaspecies occur in this region, and 52% are endemic to the northern rainforest. Five new biogeographic regions of the northern rainforest are identified based on centres ofBrookesiaendemicity: Montagne d'Ambre, Northwest, Tsaratanana, Northeast and East. Speciation is thought to have been facilitated in the north through geographic isolation, with the Tsaratanana mountain range and the dry forests south of Montagne d'Ambre forming barriers to dispersal, and the Tsaratanana mountains acting as a centre of isolation. The fragmented distribution of severalBrookesiaspecies of low altitude rainforest suggests a period in Madagascar's history when the climate was wetter and low altitude rainforest much more widespre

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb01767.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

The technique of mark‐release‐recapture was used to study survival before and after sexual maturity in adults of the damselflyPyrrhosoma nymphula(Sulzer). Fewer females were recaptured upon return to water to breed despite no differences in dispersal or daily survival rate between the sexes over the immature period. Because females took longer to mature than males, their poorer recapture rate was attributed to greater overall mortality during their longer maturation phase. Survivorship curves for tenerals marked at emergence suggested that overall survival of immature adults was similar to, if not better than, that of mature adults. The reasons for this are discussed.Jolly's model was used to estimate daily survival rates for mature adults. The assumptions of the model were tested rigorously. Estimates for females were statistically less reliable than those for males. Mean reproductive spans for males and females were 6.8 and 6.6 days, respectively, giving mean total adult lifespans of 19.4 days and 21.6 days for individuals surviving the maturation period.Because neither sex visited the breeding site every day, sampling exclusively at water resulted in underestimation of mean reproductive spans for both sexes. Female reproductive spans were underestimated to a greater extent; because females remain away from water longer between visits, there is a greater chance that they will die before being recaptured.Mean reproductive spans were also underestimated when only a sub‐section of the habitat was sampled. Females were significantly more mobile than males and this increased the likelihood that they would move out of the study area, resulting in more severe underestimation. The importance of obtaining accurate estimates of mature lifespan for females is disc

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb01768.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

We provide evidence that normal plasma zinc levels in snakes are in the same range as the elevated zinc levels associated with haemolytic anaemia and fatal zinc toxicosis in dogs, and with weight loss and anorexia in crocodiles that had ingested coins with high zinc content. Blood plasma samples from large representative groups of snakes, lizards, turtles and alligators were analysed for zinc content by atomic absorption spectrophotometry. Plasma zinc levels in all snake species were five to 50‐fold greater than levels reported in mammals. Plasma zinc levels in lizards and turtles were also higher than those of mammals, but significantly lower than those of snakes. Plasma zinc levels in alligators were in the same range as mammals and birds. After prolonged dialysis of snake plasma, 76% of the zinc remains in the retentate, suggesting the presence of a plasma protein with a strong affinity for the metal. Zinc levels vary significantly among the taxonomic groups, emphasizing the common evolutionary origin of crocodiles and birds and their divergence from the other reptile

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb01769.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

The theraphosid spiderTheraphosa leblondi(Latreille) produces a sibilant, hissing sound during defensive displays. This sound is produced using a previously undescribed method of stridulation: setal entanglement. The opposing surfaces of the femora of the pedipalps, first, and second pair of legs are clothed in unique setae which have their distal portion bearing hooks and a shaft clothed in filaments. Experimental ablations described here showed these plumose setae to be the site of sound production. Based on examination of the fine structure of these setae, we propose that the hissing sound is produced by the entanglement and pulling apart of the hooks at the ends of the setae on one leg surface and the long, plumose filaments on the median part of the setae on the opposing leg surface. Evidence presented suggests that this is a case of an acoustic aposematic display directed at vertebrate predators.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb01770.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

The short‐nosed fruit bat(Cynopterus sphinx)creates bell‐shaped cavities in flower/fruit clusters of the kitul palm(Caryota urens)by chewing and severing flower and fruit strings. These cavities (stem tents) in which the bats roost are usually about one metre deep and 30 cm in diameter. We observed groups of bats roosting in fully‐formed stem tents during the daytime, and the construction and subsequent occupancy of newly formed tent cavities. Stem tents are similar in principle to leaf tents except, instead of being formed when bats chew veins and the surrounding tissues of leaves, stem tents are formed inC. urenswhen bats completely cut several of the central flower/fruit strings. Flower/fruit strings are mostly severed when they are in an immature stage, at times when they are thin and widely spaced. Once these strings thicken and become heavily‐laden with mature fruits, bats cannot penetrate the cluster to sever them. Our observations suggest that a single male enters an immature flower or fruit cluster either from below or the sides and severs the central strings along the peduncle. In early phases of stem‐tent construction,C. sphinxsevers flower/fruit strings at a rate of about one or two per day, and cluster alteration may continue upwards to two months. Only one immature flower/fruit cluster on aC. urenstree is available for alteration by bats at any given time. That this bat does not roost in the fruit/flower cluster during the day, when a tent is under construction, and the accumulation of chewed flower and fruit strings beneath such a cluster in the morning, suggests that tent construction byC. sphinxis a night‐ti

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb01771.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Jumping ability varies by two‐fold within an instar during the moult cycle in the grasshopper,Schistocerca americana(Acrididae: Cyrtacanthacridinae). Changes in jump distance could result from deviations in jump angle away from the optimum during development, a change in jump energy and/or a change in body mass. Body mass has already been shown to vary by over two‐ fold within an instar (Queathem, 1991). In the present study, jump angle remained near the optimum of 43° during the time course of maximal jumps throughout the instar. Jump energy was correlated with ground reaction force production because energy lost to backward rotation and drag was small. Ground reaction force production varied by nearly four‐fold over the period of the instar. Within instar six, force production and body mass accounted for 85% of the variation in jump distance. Their patterns of change relative to one another explain the four functional stages we define for within instar performance. Jump distance increased early within instar six (Stage I, days 0–2) because force production increased. In Stage II (days 3–8), jump distance remained at its peak because an increase in body mass was offset by an equal increase in force production. Jump distance decreased in Stage III (days 8–11) because body mass continued to increase while force production levelled off. Force production decreased to a greater extent than body mass during Stage IV (days 11–13), resulting in a further decline in jump distance during the three days preceding the moult to adulthood. Our results suggest that further examination of the musculo‐skeletal system could provide a causal explanation for this change in jumping ability within an instar. The present study illustrates the remarkable physiological and mechanical changes that affect locomotion within a single instar, and highlights developmental differences between arthropods and vertebrates. Arthropod development is by its very nature a discontinuous process separated by periods of continuous, parabolic changes, and this pattern of growth is reflected in locomotor performance

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb01772.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Inside the viable range 36–39°C, the development of the domestic guinea fowl embryo was studied during artificial incubation of about 5000 eggs. Equations giving internal and external pipping and hatching time as a function of incubation temperature were developed. Whatever temperature was used, internal and external pipping occurred at 89% and 95% of hatching time, respectively. The chronological developmentin ovoof the guinea fowl is illustrated by growth curves. Guinea fowl grewin ovoat the same rate as the chicken embryo. The embryonic mortality is significantly affected by incubation temperature. The thermal tolerance of the embryo follows a parabolic curve: temperatures below or above 37.2°C increase the rate of mortality. During the course of the incubation, the mortality frequency was mainly distributed around two peaks (each one third of the total), which occurred during the first days of incubation, that is, within the first 12% of the incubation time, and during the last days, that is, after 85% of the incubation time. At the optimal 37.2°C temperature, these two peaks occurred on days 1–3 and 23–27, resp

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb01773.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Activity patterns and emergence times of a colony of serotine bats,Eptesicus serotinus, were studied in southern England. Time of emergence from the day roost varied over the summer but was strongly correlated with sunset. Mean emergence time was 11.6 ± 7.7 min after sunset. Early in summer, activity patterns were unimodal, becoming bimodal during mid‐ to late pregnancy and multimodal in early to mid‐lactation. When juveniles were volant, activity patterns became unimodal again. Periods of low ambient temperature were associated with reduced activity. The duration of the first foraging flight decreased as pregnancy progressed, possibly as a result of the greater wing‐loading caused by increased body mass. However, the first foraging flight increased in duration during the course of lactation, probably in response to a combination of increased night length and the increased energetic demands of milk production. It is concluded that seasonal variation in the length of time spent away from the roost in the serotine is related to reproductive status, night length and ambient temperature. It is suggested that the more northerly distribution of this bat in continental Europe may be due to differences in habitat use an

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb01774.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Diurnal habitat use by fallow deerDama damawas studied between 1986–9 by direct observations from transects of eight populations in sites of differing environmental structure and composition. Sites chosen differed in the overall proportion of woodland cover, and ranged from virtually continuous woodland areas in the New Forest, southern England, to open agricultural sites with only scattered woodland copses.Within both New Forest and agricultural areas, individuals in male groups and female groups showed similar patterns of habitat use. In the New Forest, the habitat used most overall by both sexes was open woodland, with extensive use also made of grassland, woodland clearings and closed woodland. In agricultural areas, most extensive use was made of closed woodland, with open woodland, arable land and grassland used to a lesser extent. Individuals in mixed‐sex groups in the New Forest but not in agricultural areas made more extensive use of grasslands than those in single‐sex groups.Individuals in female groups in the New Forest showed pronounced seasonal variation in habitat use with utilization of open woodland higher in autumn and winter and grassland higher in spring and summer. Individuals in female groups in agricultural areas showed little seasonal variation in habitat use. There were insufficient data to investigate seasonal variation in habitat use by individuals in male and mixed‐sex groups.Availability of habitat types varied widely between study sites. Use of either open or closed woodland remained high in each site reflecting increased selection for woodland resources when they were of limited availability. Fallow deer appeared able to satisfy their ecological and behavioural requirements from a variety of environments through: (i) changing strength of selection of particular habitats to compensate for differing availability; and (ii) substitution of one habitat in one area for a different habitat in another area which offered the same effective resources. This flexibility in resource use parallels observed plasticity in other aspects of fallow behavioural

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb01775.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Six British species of the Cheilostomatous bryozoan genusSchizomavellaCanu&Bassler, 1917 are described and figured. Neotype specimens are selected forS. auriculata(Hassall) andS. linearis(Hassall), and lectotypes are selected forS. cuspidata(Hincks) and 5.hastata(Hincks). S.hastiformisHayward and Ryland is placed in synonymy withS. linearis. S. sarniensissp. nov.is described from several south‐west British localitie

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1995.tb01776.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY