The recent rise to the alpha-rank in a population of free-living chimpanzees

The recent rise of a high-ranking adult male chimpanzee to the alpha male position of the Gombe National Park's Kasakela chimpanzee community is reported. The male Figan is the fourth individual to assume this status in the wild chimpanzees' social hierarchy during Goodall's 16 year study in Tanzania. The paper describes the overthrow of the previous top-ranking male, and the manner in which Figan has maintained his new position after the take-over. Emphasis is placed upon his relationship with his elder male sibling, Faben, and the second highest-ranking male in the community, Evered.     

半圈养条件下白唇鹿行为时间分配及活动规律的研究

白唇鹿 (Cervus albirostris)是我国青藏高原特有种 ,在鹿类进化史上极其重要。因其药用价值很高 ,几十年来捕杀现象严重 ,数量大为减少 ,濒于灭绝 ,1 988年被列为国家一级保护动物 [13 ] 。目前白唇鹿分布在 2 9°～ 40°N,92°～ 1 0 2°E的区域内[1] 。它们主要活动于海拔 350 0～ 50 0 0 m之间的高寒半荒漠草原 ,高山草甸草原和亚高山灌丛草原 [7] 。国内对白唇鹿的研究 ,涉及到食性[7,11] 、繁殖[3～ 5] 、形态、生态地理分布[6] 等 ,而对白唇鹿非发情期行为时间分配尚无报道。 1 998年 3～ 4月我们在上海野生动物园对其进行了专题研…     

Social rejection,exclusion, and shunning among the Gombe chimpanzees

From the observations at Gombe over the past 23 years it appears that group punishment of deviant behavior through ostracism, as practiced in human groups, has not yet evolved in a truly sophisticated way in chimpanzee society. However, cases of “social rejection or exclusion” have been observed in three different behavioral contexts. Most frequently, a chimpanzee is the target of hostility as the result of competitive interaction within the community; in such cases, social cohesion counterbalances rejection, typically leading to integration within a relatively stable pattern of dominance and social interaction. The occasional departure of an individual who has been the target of aggression —like the withdrawal of Evered after repeated attacks by Figan and Faban—seems due to persistent hostility by a few males rather than general “ostracism” by the group as a whole. A second form of exclusion concerns outsiders found in the home range of the group: in these cases, hostility is more generalized, particularly in response to the attempt of an adult female with offspring to join the community. Finally, there are the rarely observed instances of shunning a group member whose behavior seems abnormal the social rejection of Pepe and Old Mr. McGregor after they suffered from polio.     

Gestational length in the koala, Phascolarctos cinereus

We report a possible case of extended gestation in the koala, Phascolarctos cinereus. Birth of a pouch young was first observed 127 days after the removal of the male from a multi-female colony at Taronga Zoo. No other males were present at that time or had access to the facility. Head measurements and other growth data collected at the time of detection and over the period of pouch life indicates the time from removal of the male and the date of birth to be between 50 and 77 days. DNA fingerprinting using microsatellite loci unambiguously assigned paternity of the pouch young to this male.

These observations suggest either an extended period of gestation of at least 50 days, or activation of a dormant blastocyst from the previous breeding season, as the female entered the period of seasonal oestrus.     

Dietary constraints on sexual activity, mating success, and survivorship of male Delia antiqua

The effects of protein-deprivation on the sexual activity and reproductive fitness of male onion flies, Delia antiqua (Meigen) (Diptera: Anthomyiidae), were investigated under laboratory conditions. The percentage of males inseminating gravid females, the magnitude of ovipositional response, and the total numbers of eggs deposited in 1:1 or 1:10 male:female matchings over two days was unaffected by deprivation of dietary protein. The LT₅₀'s (median survival time) for solitary males provided proteinaceous, sucrose, or water diets were 38.0, 25.8, and 6.0 days, respectively. Yet independent of diet effects, males lost 50% of their wing tissue by fragmentation after 26 days, suggesting that wing condition is more important in determining male reproductive fitness than longevity. Male mating frequency in single pairings with previtellogenic females deprived of proteinaceous diet for ten days was similar to that of gravid, protein-fed females. In no-choice and choice mating bioassays at a 10:1 female:male ratio, however, males inseminated significantly fewer previtellogenic than gravid females over 24 h. Despite evidence for male autogeny, removal of exogenous protein resources in the Allium agroecosystem may have important effects on the reproductive competency and fecundity of D. antiqua.     

The Role of Scent Marking in Mate Selection by Female Pumas (Puma concolor)

Mate selection influences individual fitness, is often based on complex cues and behaviours, and can be difficult to study in solitary species including carnivores. We used motion-triggered cameras at 29 community scrapes (i.e. scent marking locations used by multiple individuals) and home range data from 39 GPS-collared pumas (Puma concolor) to assess the relevance of communication behaviours for mate selection by female pumas in California. Female pumas visited community scrapes irregularly and visitation bouts appeared to be correlated with oestrus. Female pumas on average selected from 1.7 collared males, and selection was based on multiple cues that varied among the different time periods measured (i.e. the female’s visitation bout and in 90 days previous to the consorting event). Female mate selection over the course of a visitation bout was based on frequency of the male visitation, mass, and age. In the 90 days previous to consorting, the number of scrapes a male created was the most important contributor to selection, which was likely related to his residency status. We also found that at least 14% of females mated with multiple males, thus possibly confusing paternity. Our findings provide a mechanistic understanding of how female pumas use scent and auditory communication at community scrapes to select dominant resident males to mate with.     

Effect of deuterium oxide on the pituitary gonadotrophs of the brown spiny mouse. Mus platythrix Bennett.

Adult individuals of M. platythrix were maintained on 30 per cent D2O by volume in drinking water at varying periods of time. Qualitative and quantitative changes in pituitary FSH and LH cells were observed. The former revealed hyperplasia and hypertrophy by 10 days attaining their peak of activity and hyalinization by 20 days. In contrast response in the LH cells was rather slow. They showed a significant increase in number after 30 days and hyalinization by 50 days. FSH cells revealed decline in activity by 50 days whereas LH cells attained their peak numerically by 40 days and underwent no change thereafter. These observations suggest that in the adult male D2O reveals: 1. hyperactive influence on the gonadotrophs, and 2. differential in FSH and LH secreting cells.     

The degradation of the herbicide bromoxynil and its impact on bacterial diversity in a top soil

Aims: To study how repeated applications of an herbicide bromoxynil to a soil, mimicking the regime used in the field, affected the degradation of the compound and whether such affects were reflected by changes in the indigenous bacterial community present. Methods and Results: Bromoxynil degradation was monitored in soil microcosms using HPLC. Its impact on the bacterial community was determined using denaturing gradient gel electrophoresis (DGGE) and quantitative PCR of five bacterial taxa (Pseudomonads, Actinobacteria, α‐Proteobacteria, Acidobacteria and nitrifying bacteria). Three applications of 10 mg kg^?1 of bromoxynil at 28‐day intervals resulted in rapid degradation, the time for removal of 50% of the compound decreasing from 6·4 days on the first application to 4·9 days by the third. Bacterial population profiles showed significant similarity throughout the experiment. With the addition of 50 mg kg^?1 bromoxynil to soil, the degradation was preceded by a lag phase and the time for 50% of the compound to be degraded increased from 7 days to 28 days by the third application. The bacterial population showed significant differences 7 days after the final application of bromoxynil that correlated with an inhibition of degradation during the same period. Conclusions: These analyses highlighted that the addition of bromoxynil gave rise to significant shifts in the community diversity and its structure as measured by four abundant taxa, when compared with the control microcosm. These changes persisted even after bromoxynil had been degraded. Significance and Impact of the Study: Here we show that bromoxynil can exert an inhibitory effect on the bacterial population that results in decreased rates of degradation and increased persistence of the compound. In addition, we demonstrate that molecular approaches can identify statistically significant changes in microbial communities that occur in conjunction with changes in the rate of degradation of the compound in the soil.     

Effect of sheep urine deposition on the bacterial community structure in an acidic upland grassland soil

The effect of the addition of synthetic sheep urine (SSU) and plant species on the bacterial community composition of upland acidic grasslands was studied using a microcosm approach. Low, medium, and high concentrations of SSU were applied to pots containing plant species typical of both unimproved (Agrostis capillaris) and agriculturally improved (Lolium perenne) grasslands, and harvests were carried out 10 days and 50 days after the addition of SSU. SSU application significantly increased both soil pH (P < 0.005), with pH values ranging from pH 5.4 (zero SSU) to pH 6.4 (high SSU), and microbial activity (P < 0.005), with treatment with medium and high levels of SSU displaying significantly higher microbial activity (triphenylformazan dehydrogenase activity) than treatment of soil with zero or low concentrations of SSU. Microbial biomass, however, was not significantly altered by any of the SSU applications. Plant species alone had no effect on microbial biomass or activity. Bacterial community structure was profiled using bacterial automated ribosomal intergenic spacer analysis. Multidimensional scaling plots indicated that applications of high concentrations of SSU significantly altered the bacterial community composition in the presence of plant species but at different times: 10 days after application of high concentrations of SSU, the bacterial community composition of L. perenne-planted soils differed significantly from those of any other soils, whereas in the case of A. capillaris-planted soils, the bacterial community composition was different 50 days after treatment with high concentrations of SSU. Canonical correspondence analysis also highlighted the importance of interactions between SSU addition, plant species, and time in the bacterial community structure. This study has shown that the response of plants and bacterial communities to sheep urine deposition in grasslands is dependent on both the grass species present and the concentration of SSU applied, which may have important ecological consequences for agricultural grasslands.     

Estrogen uptake capacity of individual pituitary cell types from male and female rats one, fourteen and fifty days after castration

A quantitative autoradiographic technique was combined with immunocytochemical staining to compare 3H-estrogen uptake in individual pituitary cell types 1, 14 or 50 days after castration in both male and female rats. Silver grains were counted over nuclei of immunocytochemically stained cells and means were computed for each cell type. The order of labelling intensity for all groups was gonadotropes greater than or equal to lactotropes = somatotropes greater than thyrotropes = corticotropes. In male rats 3H-estrogen uptake capacity in all of these cell types remained unchanged over the post-castration interval. Only gonadotropes from female rats demonstrated a significant change in estrogen uptake capacity over the intervals examined. Uptake in these cells increased by 137% between 1 and 50 days after ovariectomy. At both 14 and 50 days post-ovariectomy, gonadotropes concentrated significantly more radioactive label than either lactotropes or somatotropes. One day after castration, gonadotropes from females concentrated less 3H-estrogen than males while at 50 days after castration they concentrated significantly more than gonadotropes from male rats.     

Schistosoma mansoni: male-biased sex ratios in snails and mice

Adult sex ratios of Schistosoma mansoni, in mice, were shown to be biased toward males (3:1) despite the finding that sex ratios of miracidia were 50:50. The adult male bias was caused by greater male infectivity of miracidia for snails and cercariae for mice. A significantly higher percentage of male miracidia developed to cercarial production in unimiracidial infections (57 male, 34 female), and a significantly higher percentage of male cercariae developed to adulthood in mice (143 male, 79 female worms resulted from 900 male and 900 female cercariae). No significant differences were found between male and female parasites for longevity of miracidia (both sexes, 10 hr) and cercariae (males 21.3 +/- 5.75 hr, females 25.0 +/- 7.02 hr), prepatent periods in snail hosts (male 34 +/- 2.92 days, females 33 +/- 2.36 days), longevity of snail infections (males 96.6 +/- 25.15 days, females 115.2 +/- 82.43 days), and the numbers of cercariae produced per snail lifetime (males 30,751.44 +/- 18,064.33, females 34,083.00 +/- 33,732.82). Present results provide a better understanding of the life cycle of S. mansoni, are of theoretical significance for theories of biased sex ratios (which at present cannot account for the male-biased ratio of S. mansoni), and also suggest that schistosomiasis transmission models assuming a 50:50 sex ratio at all stages of the life cycle should be reassessed.     

Modulation by neonatal thymectomy of the reproductive axis in male and female rats during development

The effects of neonatal thymectomy, at 3 days of age, on parameters of the reproductive axis were examined in male and female Sprague-Dawley rats. Gonadal and accessory sex tissue (male: epididymis, seminal vesicle, and ventral prostate; female: uterus) weights as well as anterior pituitary, spleen, and adrenal weights were determined in the thymectomized and sham-thymectomized animals at 20, 30, 40, 50, 60, and 90 days of age. Plasma gonadotropin concentrations as well as pituitary content of the gonadotropins and prolactin were assessed at each of these time intervals. No significant difference in gonad and accessory sex tissue weights was detected in thymectomized versus sham-operated controls at each of these times. Adrenal weights were increased in thymectomized animals compared with controls at 50 days of age and older in male rats and at 90 days in females. Spleen weights were decreased in the thymectomized males at 50 and 60 days of age. Thymectomy did not affect the spleen weight of females. Plasma concentrations of gonadotropins were unaffected in thymectomized males but were altered in females during the pre- and peripubertal period (Days 20-40). Vaginal opening, however, occurred at the same time in the thymectomized and control females. Pituitary gonadotropin and prolactin content were unaffected by thymectomy of the females, except at 90 days when pituitary luteinizing hormone (LH) content was lower in thymectomized than in control animals. LH and prolactin content were significantly reduced in the males at 60 and 90 days of age. These results demonstrate that there are sexual differences in the effects of thymectomy on parameters of the reproductive axis.(ABSTRACT TRUNCATED AT 250 WORDS)     

The Foraging Costs of Mating Effort in Male Chimpanzees (Pan troglodytes schweinfurthii)

Costs of mating effort can affect the reproductive strategies and lifetime fitness of male primates, but interspecific and interindividual variation in the magnitude and distribution of costs is poorly understood. Male costs have primarily been recognized in seasonally breeding species that experience concentrated periods of mating competition. Here, we examine foraging costs associated with male mating effort in chimpanzees (Pan troglodytes schweinfurthii), a polygynandrous species, in which mating opportunities occur intermittently throughout the year. To quantify male feeding, aggression, and mating, we conducted focal follows on 12 males in a wild community (Kanyawara, Kibale National Park, Uganda) for 11 mo. Males fed less on days when high-value mating opportunities (estrous parous females) were available than on days without any mating opportunities. Reductions in feeding time were related to increased rates of aggression and copulation, indicating that the proximate cause of changes in male foraging was mating effort. Surprisingly, however, there was no relationship between dominance rank and the extent to which feeding time was reduced. High costs of mating effort may reduce the degree of reproductive skew and limit the use of possessive tactics in chimpanzees. We suggest that male bonding in chimpanzees may be favored not only for its benefits but because intragroup competition is so costly. Our results complement the available data on mammals, and primates in particular, by showing that mating effort can have measurable foraging costs even in species, in which breeding is aseasonal and only moderately skewed.     

Cold-tolerance of the oriental cockroachBlatta orientalis

The cold-hardiness of nymphal stages 1 to 5 and adult male and femaleBlatta orientalis was tested at 2°, −5° and −10°C. The LT50 (time) of insects exposed to −5° ranged from 0.21 to 0.43 days. Acclimation at 10° C for times varying up to 14 days progressively increased cold-hardiness. A 14 day acclimation at 10° prior to exposure at −5°C increased LT50 (time) to 1.1–4.2 days for the various stages; prolonging the acclimation time to 28 days produced no further increase in LT50. All stages were rapidly killed at −10°C (LT50<0.04 days) and survived prolonged exposures at 2°C (LT50s from 16 to >42 days) following acclimation. The potential for survival of outdoor populations ofB. orientalis over winter is discussed.     

The effects of aging on carbonic anhydrase concentrations in rat liver and skeletal muscle.

The isoenzymes carbonic anhydrase II (CAII) and III (CAIII) have been measured by radioimmunoassay in the livers of male and female rats aged from 21 to 800 days. No sexual dimorphism at 21 days was found, but from 50 to 400 days both isoenzymes show sexual differences. From 600 days onwards, these differences are less apparent. CAIII concentrations in two 'fast' fibre muscles and one 'slow' fibre muscle have been determined. There is no sexual dimorphism in muscle, but a wide variation between individuals was observed. Fast muscles show maximal CAIII levels at 800 days, whereas in slow muscle the concentration of the isoenzyme is declining at this time.     

Developmental time,longevity, reproductive capacity and sex ratio of the mealybug parasitoid Anagyrus sp. nr. pseudococci (Girault) (Hymenoptera: Encyrtidae)

Key biological parameters of Anagyrus sp. nr. pseudococci reared on the citrus mealybug Planococcus citri (Risso) were determined. The mean longevity of female wasps was 21.1 days, the median lethal time (LT₅₀) was 22 days, the mean number of offspring per female was 30.2 wasps and the sex ratio of the progeny was slightly male biased (1.1 males per female). Wasps fed with water showed a significantly lower longevity compared to that recorded for wasps fed with syrup for bee nutrition mixed with water. The longevity of female wasps was significantly higher compared to males when the syrup-water solution was provided as food. Longevity was significantly higher for female wasps fed with syrup and water in comparison with those exposed to host mealybugs. The mean development time of female and male wasps was 14.7±0.1 and 14.5±0.1 days, respectively.     

Effects of extremely low frequency magnetic field on fertility of adult male and female rats.

To investigate the effects of an extremely low-frequency (ELF) magnetic field on their fertility, adult male and female Sprague-Dawley rats were exposed to a 50 Hz sinusoidal magnetic field of approximately 25 microT (rms) for 90 days before they were mated with unexposed counterparts. Exposure to a 50 Hz field reduced male rat fertility. The number of pregnant females was reduced when mated with exposed males, and the number of resorptions increased. The effects of magnetic field on male fertility were shown to be partly reversible, when the same exposed group of males were remated 45 and 90 days after being removed from the fields. Exposure of adult female rats to 50 Hz magnetic fields for 90 days before mating significantly reduced their fertility. The mean numbers of implantations and living fetuses per litter were statistically significantly decreased in the 50 Hz group. These results suggest that low frequency magnetic fields have some adverse effects on fertility of male and female rats.     

Heat Stress Impedes Development and Lowers Fecundity of the Brown Planthopper Nilaparvata lugens (St?l)

This study investigated the effects of sub-lethal high temperatures on the development and reproduction of the brown plant hopper Nilaparvata lugens (Stål). When first instar nymphs were exposed at their ULT₅₀ (41.8°C) mean development time to adult was increased in both males and females, from 15.2±0.3 and 18.2±0.3 days respectively in the control to 18.7±0.2 and 19±0.2 days in the treated insects. These differences in development arising from heat stress experienced in the first instar nymph did not persist into the adult stage (adult longevity of 23.5±1.1 and 24.4±1.1 days for treated males and females compared with 25.7±1.0 and 20.6±1.1 days in the control groups), although untreated males lived longer than untreated females. Total mean longevity was increased from 38.8±0.1 to 43.4±1.0 days in treated females, but male longevity was not affected (40.9±0.9 and 42.2±1.1 days respectively). When male and female first instar nymphs were exposed at their ULT₅₀ of 41.8°C and allowed to mate on reaching adult, mean fecundity was reduced from 403.8±13.7 to 128.0±16.6 eggs per female in the treated insects. Following exposure of adult insects at their equivalent ULT₅₀ (42.5°C), the three mating combinations of treated male x treated female, treated male x untreated female, and untreated male x treated female produced 169.3±14.7, 249.6±21.3 and 233.4±17.2 eggs per female respectively, all significantly lower than the control. Exposure of nymphs and adults at their respective ULT₅₀ temperatures also significantly extended the time required for their progeny to complete egg development for all mating combinations compared with control. Overall, sub-lethal heat stress inhibited nymphal development, lowered fecundity and extended egg development time.     

Song development in the white-crowned sparrow: social factors and sex differences

Results of earlier studies indicated that hand-raised white-crowned sparrows exposed to taperecorded songs learned conspecific song between ages 10–50 days, but not before or after that age. These studies also indicated that allospecific songs were not learned. We describe song development in 41 male and 22 female hand-raised white-crowned sparrows. Thirty males and 15 females were exposed to a live adult singing male. It was found that most male students learned the song of their live tutor even though tutoring was begun at 50 days of age, an age by which young would have dispersed from the natal to the breeding area. Male students learned allospecific song as easily as they did conspecific song, even though conspecific song was present in the laboratory. Only three females copied any part of the song of either conspecific or allospecific live tutors. Six 50-day-old males and seven females were exposed to taperecorded song and none learned the tutor song. These results indicate that there are sex differences in song learning, and that, if live tutors are used, the sensitive phase for male song learning extends beyond 50 days of age. We conclude that social interaction can override any auditory gating mechanism that prevents inappropriate stimuli from influencing song learning centres.     

Does flower color variation matter in deception pollinated<Emphasis Type="Italic"> Psychilis monensis</Emphasis> (Orchidaceae)?

Negative frequency dependent selection (FDS) had been proposed as a mechanism for the maintenance of the high levels of variability in floral traits of rewardless plants. Thus far the evidence has been equivocal for discontinuous traits. We experimentally tested the FDS hypothesis for continuous variation in flower color of Psychilis monensis, a rewardless, epiphytic orchid of Mona Island, Puerto Rico. P. monensis flowers all year long with a peak in June and July. Plants are self-incompatible. Individual flowers last 9–15 days if unpollinated. Over a 9-month observation of an unmanipulated population, a high percentage of plants showed pollinarium removals (79%) and fruit initiation (63%), but the actual percentage of flowers visited was very low (12%) and final fruit set was as low as the lowest recorded for orchids (2.4%). In a FDS experiment using a Latin Square design, we manipulated flower color in three populations. Over 50% of the variation in either male or female reproductive success was explained by time and site with no significant effect of treatment except as part of a three-way interaction of time × site × treatment. Paired comparisons with the controls gave equivocal results for both male and female measures of reproductive success. Major community changes had occurred during the FDS experiment with flower activity falling dramatically and by the third run of the experiment, only P. monensis was in flower. Coincidentally, the numbers of effective visits increased with time, presumably as pollinators became less discriminating in search of new food resources. Thus, negative frequency dependent selection is either sporadic or non-existent. Reproductive success was statistically related to locality and date, which was reflected in the flowering phenology of the local communities. High natural levels of color variation may be more influenced by drift than selection.