摘要:

Incubation temperature is known to affect pigmentation in turtles and alligators, but the influence of other incubation parameters on pigmentation has not been reported previously. We examined the pigmentation of hatchling red‐eared slider turtles,Trachemys scripta elegans, incubated under various temperatures and gaseous conditions in the course of three prior studies. Reduced levels of oxygen during embryogenesis did not affect pigmentation, although such levels had produced small significant changes in developmental time. Elevated levels of carbon dioxide during development had a greater influence on pigmentation than did incubation temperature without producing as great a lengthening of incubation time. Hence, the changes in pigmentation produced by temperature and carbon dioxide could not be simply a function of their effects on developmental time. The carbon dioxide and temperature produced parallel changes in plastral pattern. In contrast, carbon dioxide had marked effects on skin pigmentation that were not paralleled by those of temperature. In addition, there were some significant differences among clutches in the effects of incubation temperature and carbon dioxide on pigmentation. Some of the differences in pigmentation among incubation treatments for this species are similar in magnitude to those occurring naturally among related turtle species. The ability to alter various developmental sequences differentially by changes in incubation conditions will facilitate both developmental and comparative evolutionary studie

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02704.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

A group of 20 pipistrelle bats were taken into captivity and allowed free flight and association within a flight room where they gave birth to and successfully reared 17 young. The flight of the females was recorded during pregnancy, early lactation and post‐lactation by using stroboscopic stereophotogrammetry (153 flights reconstructed in total). During the investigation body mass was altering owing to reproductive condition, and changes in mass were recorded daily for all (adult and juvenile) bats during the entire study period, which lasted from two weeks before the last birth until release, when the oldest baby was 43 days old. All bats were individually marked, and detailed morphological measurements were made. Pregnant and post‐lactating bats were heavier than lactating bats, which showed the lowest wingbeat frequencies. The flight speeds of pregnant, lactating and post‐lactating bats showed no significant differences, and this may be because the pregnant bats appeared to have a wider scope for selecting flight speed than the other two reproductive groups, or than animals studied previously. The group of bats as a whole decreased flight speed (scaling as M‐043) and increased wingbeat frequency (scaling as M0.58) as their mass increased. Wingbeat amplitude showed no relation to body mass, wing area or span, flight speed or frequency. A flight performance model applied to the experimental results and optimum flight conditions is used to predict cost of transport and mechanical power for steady flight, and equilibrium wingbeat amplitude which is compared with obser

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02705.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Nocturnal and siesta resting ecology and behaviour of 24 Egyptian mongooses were studied. Mongooses mainly used underground dens (rabbit warrens and badger setts) and thickets in both periods. Tree hollows were occasionally used. Twenty‐one individuals used 338 different nocturnal resting sites on 672 occasions. Mean number of resting sites per individual was 16.1, though resting sites used by each individual increased when sample size did. Mean re‐use rate was 1.99 nights/site. The majority of nocturnal resting sites were only used once, and very few more than five times. Nocturnal resting sites used two or more times were significantly more often inside than outside home range core areas, whereas resting sites used once were significantly more often outside than inside. Mean distance between consecutive nocturnal resting sites was different among classes of individuals, and annual variations were detected. Eighteen mongooses used 133 different resting sites on 171 occasions during siesta periods. Mean number of different sites used and re‐use rate were 7.4 and 1.29, respectively. Types of resting sites used during siesta periods changed throughout the year with underground dens predominating in summer. Re‐use rates remained constant for the whole year. The impacts of social structure and summer high temperatures on mongoose resting behaviour are di

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02706.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The feeding ecology of two small‐bodied primate species—saddle‐back (Saguinus fuscicollis auilapiresi) and moustached tamarins (S. mystax pileatus)—occurring in stable, mixed‐species groups was studied in aterra firmeforest site in the upper Urucu River, Amazonas, Brazil. Ecological data are based primarily on one mixed‐species group of 5–8 saddle‐back and 8–10 moustached tamarins. The overall vegetative and animal‐prey components of each tamarin species' diet, their selection of food species, and the seasonal variation in their use of plant resources are described, and compared to those of callitrichids elsewhere. The extremely diverse diet of tamarins included at least 136 tree, 33 vine and liana, 12 epiphyte and nine shrub species, as well as a wide range of prey items. They fed primarily on ripe fruit pulp of most of these species for most of the year, but shifted to floral nectar and plant exudates of a few key plant species during the dry season. Taxonomic overlap in plant diet was nearly complete between the two tamarin species, but they diverged considerably in their prey capture techniques. Saddle‐backs used the low forest understorey, and manipulatively searched for sedentary prey concealed within discrete, usually rigid, microhabitats, whereas moustached tamarins used the midstorey where they visually searched for mobile prey well exposed on foliage. These and other feeding and foraging patterns are discussed in the light of other callitrichid sp

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02707.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The relative importance of age and photoperiod in the timing of seasonal cycles was studied in red deer during the first 18 months of life. Seasonal cycles of appetite, live‐weight change, coat growth, oestrus and metabolic rate were examined in two groups of seven hind calves born in early May (group E) or nine weeks later in July (group L).There was no difference between groups in the timing or amplitude of the seasonal voluntary food intake (VFI) cycle, or in the timing of seasonal changes in rate of live‐weight gain, although mean live‐weight gain was significantly greater for group L than group E during the first winter of life.Four animals in group L retained their calf coats throughout the first winter. In group L, the first summer coat fibres appeared approximately four weeks earlier, and mean fibre length for the subsequent winter coat was longer in group L than in group E. There was no difference between groups in the timing or amplitude of the seasonal cycle of plasma prolactin concentration, or in the incidence and mean time of onset of puberty.There was no difference between groups in mean energy expenditure per unit of live weight at any time of the year. Mean daily energy expenditure was significantly higher in summer than in winter, but values measured when the animals were resting and corrected for differences in VFI were similar throughout the year.It is concluded that the seasonal cycles of appetite, live‐weight change and oestrus in young red deer hinds are not modified by age, although the normal cycle of coat replacement can be disturbed in animals born towards the end of the calving

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02708.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The woodmouse is a characteristic rodent of deciduous woodland but it also lives on maritime sand‐dunes. The population density of woodmice on sand‐dunes is much lower than in woodland. Hue we test the hypothesis that this difference is due to the fact that woodland provides substantially more food than do sand‐dunes. Our experimental approach was to provide supplementary food (wheat grain) to a sand‐dune population for a period of 22 months and to compare demographic responses with a control population.The supplemented population increased rapidly and reached a size 6–7 times that ofthe control population. The overall annual pattern of changes in density were similar in both populations with minimum numbers in late spring, maximum numbers in autumn and a loss of individuals over the winter. The woodmice receiving supplementary food bred earlier and for longer than did the con

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02709.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Mean apparent dry mass absorption efficiency byP. auritusfed on mealworms was 0.853 (S.D.=0.4, n=43). Mean apparent energy absorption efficiency byP. auritusandM. daubentonifed on mealworms was 0.90 (S.D.=0.007, n=8). The mean energy content of mealworms was 28.6 kJ.g‐1dry mass (S.D.=1.1, n=8), and that of faeces was 19.5 kJ.g‐1(S.D.=0.7, n=8) inP. auritusand 19.9 kJ.g‐1(S.D.=1.3, n=8) inM. daubentoni. Water content of mealworms was 61.1% wet mass (S.D.=1.4, n=173); water content of faeces was 73.3% inP. auritus(S.D.=6.8, n=76) and 72.3% (S.D.=7.0, n=42) inM. daubentoni. Oven‐dried mealworms consisted of<1% ash,<1% carbohydrate, 31% lipid and 39% protein. We suggest that the dry mass unaccounted for (28%) represented chitin, of which 59% was apparently absorbed during digestion. Apparent absorption by mass of both lipid and protein byP. auritusfed on mealworms was greater than 90%. Cumulative post‐prandial defecation was sigmoidal in both bat species with 50% (by mass) of faeces being voided within 4 h and 95% within 12 h of feeding. On the basis of previous measurements, using doubly‐labelled water, of daily energy expenditure and water flux in free‐livingP. auritus, we predict that water intake via the food, as free water and as potential metabolic water, represents 20 to 40% of total daily water flux forP. auritusduring lactatio

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02710.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Lagomorphs, many rodents and some other small mammals eat their faeces during the part of the day when they are not foraging for fresh food. One of the possible benefits of this habit of coprophagy is that it may enable them to extract more energy from their food. A computer model is used to assess the likely benefits and explore their relationships to food, feeding rate and gut morphology. The predicted benefits are much larger for hindgut fermenters than for foregut fermenters, and especially large for hindgut fermenters with relatively small fermentation chambers. They are larger for poor foods (with lower proportions of cell contents) than for richer ones. At low feeding rates the energetic advantage of coprophagy may disappear if the faeces from food eaten during one feeding period emerge largely during the next, but this can be avoided by adjusting the rate of passage of gut contents during the intervening rest period.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02711.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Fertile eggs were obtained from the nests of wild and captive‐breeding alligators in Louisiana, USA. Whereas embryo hatchability ofthe wild eggs was 94%, in the captive eggs it was only 500%. Analysis of the lipid and fatty acid compositions of the yolks showed extensive differences between the two sets of eggs. In particular, the lipids of the yolks from the captive eggs displayed considerably lower levels of C20 and C22 polyunsaturated fatty acids and higher levels of C18 polyunsaturates than the wild eggs. More specifically, overall levels of n‐6 polyunsaturates were increased at the expense of n‐3 acids in the captive eggs. In view of the specific role of C20 and C22 polyunsaturated fatty acids in embryo development, it is proposed that the yolk fatty acid compositional differences and the difference in hatchability are assoc

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02712.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The influence of mild temperature (20 d̀C) combined with different photoperiods (natural day length; 16L: 8D; 8L: 16D) on the testis ofGambusia affinis holbrookiduring the early (Experiment I) and late (Experiment II) phases of the testicular quiescence period was studied by histologic quantitative methods. In Experiment I (October‐January), spermatogenic development was not found in either the initial and final control fishes or the experimental groups. In Experiment II (January‐March), neither initial nor final controls showed spermatogenic development. The group subjected to the short photoperiod showed development of secondary spermatogonia but no spermatocytes. Complete spermatogenesis was observed in both the group exposed to the natural day length photoperiod and the group exposed to the long photoperiod. These results indicate that a mild temperature combined with a long photoperiod induces spermatogenesis inG. affinisin the late phase of quiesc

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1993.tb02713.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY