The performance of RDTs in detecting simian malaria varies according to RDT brand, infecting Plasmodium species, and parasite density. Most RDT brands show good performance to detect simian Plasmodium species when parasite density exceeds 200 parasites/µL.
No abstract is provided for this article.
In vertebrate societies where young are reared communally, nonbreeding helpers are usually closely related to young but often vary widely in their contributions to feeding them. Evolutionary explanations of helping behaviour have focused on whether differences in the level of contributions between helpers are related to variation in kinship. We investigated the contribution of helpers in meerkats, Suricata suricatta. The helpers varied widely in the number of food items they gave to pups and individual differences were related to variation in foraging success as well as to sex and age. When we controlled the influence of these variables, the level of contributions that helpers made to rearing pups was not significantly correlated with variation in kinship to the litters they were rearing.
We investigated cohort differences in the lifetime breeding success and survival of male red deer Cervus elaphus L. in an increasing population on the Isle of Rum, Scotland. There were significant differences in survival through different stages of the life span between 15 cohorts of males, ranging between: 0.26-1.00, calf survival through first winter; 0.56-1.00, yearling survival; 0.44-0.94, adult survival. This variation in survival was related to environmental conditions in the cohorts' year of birth, whilst controlling for annual effects. For 10 cohorts of males with complete lifetime data, mean breeding success also varied significantly, between 0.83 and 3.86. This variation, too, was associated with environmental conditions in the cohorts' year of birth. Since in many sexually dimorphic mammals, the growth and survival of males is more strongly affected by adverse environmental conditions than that of females, we expected that cohort variation would be more extreme amongst males than females. This was true, for both cohort survival and reproduction. We expected to observe selection on cohort adult body size, related to survival or reproduction. However, there was no evidence of variation in adult body size between cohorts, nor for relationships between differences in body size between cohorts and measures of survival or breeding success. Cohorts which underwent high intial mortality subsequently experienced higher adult survival than cohorts not subjected to high density-related selection early in life.
Comparative studies of social insects and birds show that the evolution of cooperative and eusocial breeding systems has been confined to species where females mate completely or almost exclusively with a single male, indicating that high levels of average kinship between group members are necessary for the evolution of reproductive altruism. In this paper, we show that in mammals, the evolution of cooperative breeding has been restricted to socially monogamous species which currently represent 5 per cent of all mammalian species. Since extra-pair paternity is relatively uncommon in socially monogamous and cooperatively breeding mammals, our analyses support the suggestion that high levels of average kinship between group members have played an important role in the evolution of cooperative breeding in non-human mammals, as well as in birds and insects.
Journal Article Mate retention, harassment, and the evolution of ungulate leks Get access T. H. Clutton-Brock, T. H. Clutton-Brock Large Animal Research Group, Department of Zoology, University of CambridgeDowning Street, Cambridge CB2 3EJ, UK Search for other works by this author on: Oxford Academic Google Scholar O. F. Price, O. F. Price Large Animal Research Group, Department of Zoology, University of CambridgeDowning Street, Cambridge CB2 3EJ, UK Search for other works by this author on: Oxford Academic Google Scholar A. D. C MacColl A. D. C MacColl Large Animal Research Group, Department of Zoology, University of CambridgeDowning Street, Cambridge CB2 3EJ, UK Search for other works by this author on: Oxford Academic Google Scholar Behavioral Ecology, Volume 3, Issue 3, Fall 1992, Pages 234–242, https://doi.org/10.1093/beheco/3.3.234 Published: 01 October 1992 Article history Received: 18 June 1991 Revision received: 28 November 1991 Accepted: 28 November 1991 Published: 01 October 1992
A fit ASA grade 1 82-year-old woman presented for an ultra low anterior resection. She had no significant premorbid conditions and was fit for elective surgery. She was premedicated with temazepam 10 mg. On arrival in the operating theatre, she had a 16-gauge intravenous cannula sited in her right forearm and, in the sitting position, had an epidural catheter sited at the T9/10 level. The depth to the epidural space was 4 cm and 5 cm of catheter was left in the space. Anaesthesia was induced with a combination of fentanyl 100 μg, midazolam 2 mg and propofol 80 mg. She was then given vecuronium 8 mg and intubated with an 8.0-mm tracheal tube after 2 min. Right internal jugular and radial arterial lines were then sited. A test dose of 3 ml of bupivacaine 0.25% plus 1 : 200 000 epinephrine was given and, 10 min later, epidural block was established with 10 ml of bupivacaine 0.25%. In the operating theatre, she was placed in the Lloyd Davis position and tilted 15 degrees head down at the request of the surgeon. Anaesthesia was maintained with 0.5–1% isoflurane in 70% nitrous oxide/30% oxygen. She was ventilated to maintain an end-tidal carbon dioxide of 4–4.5 kPa. Body temperature was maintained with a forced air warming system and monitored with a nasopharyngeal temperature probe. The operation lasted 4.5 h. After 1.5 h, an infusion of bupivacaine 0.1% with fentanyl 2 μg.ml−1 was started at a rate of 10 ml.h−1. The patient remained stable throughout the operation and received no further opioids or neuromuscular blocking agents. At the end of the operation, she was ventilated with 100% oxygen and allowed to wake up. Despite being responsive and obviously awake, her respiratory effort was poor and her tidal volumes were 100–150 ml as measured with a Wright's respirometer. Neuromuscular blockade was assessed with double burst stimulation and there was no significant block detected. Her core temperature was 36.2 °C. Her respiratory effort appeared inadequate and a blood gas revealed a Paco2 of 10.1 kPa. She was given doxapram 50 mg with no effect and so was ventilated in recovery and reassessed. It became apparent that she was fully awake and aware but had poor respiratory effort. She was also noted to have grade 3+/5 power in her legs but only grade 1/5 power in her arms. She was well analgesed but it was difficult to assess the height of the sensory block as she was still intubated. The presumed diagnosis of a high epidural block was made. The epidural infusion was stopped and she was sedated with sevoflurane and ventilated for a further 2 h, after which the sevoflurane was stopped and she was reassessed. At this stage, she had grade 4/5 power in her arms and her legs and had tidal volumes of 300–400 ml. Blood gases at this stage showed Paco2 of 6.1 kPa and PaO2 of 16.2 kPa on 40% oxygen. She was extubated and the epidural infusion was restarted. After a further 4 h in recovery, she was sent back to the ward. The rest of her recovery was uneventful. One can only assume that the cause for her respiratory failure was cephalad spread of the epidural block caused by the infusion running in a 15 degree head-down position. I have used this technique in other patients without problems and would be interested to hear if anyone else has experienced a similar problem as I can find no cases reported in the literature. There have been many studies trying to establish the effect of gravity and posture on spread of epidural anaesthesia. Grundy reported that epidural anaesthesia induced in the lateral position appeared 2 min earlier, spread two segments higher and lasted 75 min longer [1]. Hodgkinson documented that keeping patients in the sitting position for 5 min after injection of 20 ml of bupivacaine 0.75% limited cephalad spread but only in obese patients [2]. Apostolou demonstrated slightly higher and slightly longer block on the dependent side when epidural anaesthesia was induced in the lateral position, although he felt these differences were of only minor significance [3]. In 1993, Ponhold documented a decrease in maximum cephalad spread of L1 vs. T10 when epidural anaesthesia was induced with patients who had 30 degrees trunk elevation [4]. However, other investigators [5678] have reported no significant difference in the eventual spread and distribution of block regardless of position. I can find no studies documenting the effects of infusions in the epidural space in various positions. It may well be that with bolus injections of local anaesthetic, the pressure generated by the injection is such that the effect of posture is relatively small. However, one could suppose that with an infusion running at a low rate, the pressure generated at the tip of the epidural catheter is lower and hence the relative effects of posture and gravity would be much more. I am not sure how this problem could be avoided. Siting the epidural lower would mean that cephalad spread would be less likely to affect respiratory function although cephalad spread is probably not predictable and postoperatively a higher infusion rate may be required to achieve adequate analgesia. Alternatively, giving boluses of local anaesthetic via the epidural catheter rather than an infusion may encourage more even spread around the tip of the catheter as discussed above. This would appear to be a rare but important complication of epidural use in the head-down position and should be considered if such a patient presents with respiratory difficulty postoperatively.
In cooperatively breeding vertebrates, nonbreeding helpers raise young produced by dominant breeders. Although the evolution of cooperative breeding has often been attributed primarily to kin selection (whereby individuals gain “indirect” benefits to their fitness by assisting collateral relatives), there is increasing evidence that helpers can be unrelated to the young they are raising. Recent studies also suggest that the indirect benefits of cooperative behavior may often have been overestimated while the direct benefits of helping to the helper's own fitness have probably been underestimated. It now seems likely that the evolutionary mechanisms maintaining cooperative breeding are diverse and that, in some species, the direct benefits of helping may be sufficient to maintain cooperative societies. The benefits of cooperation in vertebrate societies may consequently show parallels with those in human societies, where cooperation between unrelated individuals is frequent and social institutions are often maintained by generalized reciprocity.
Studies of mate choice in vertebrates have focused principally on birds, in which male ornaments are often highly developed, and have shown that females commonly select mates on the basis of particular phenotypic characteristics that may reflect their genetic quality. Studies of female mate choice in mammals are less highly developed, and they have commonly focused on female mating preferences that are likely to be maintained by benefits to the female’s own survival or breeding success. However, recent experimental studies of mate choice in mammals—especially rodents—provide increasing evidence of consistent female preferences that appear likely to generate benefits to the fitness of offspring. As yet, there is no compelling evidence that female mating preferences are less highly developed in female mammals than in female birds, although these preferences may more often be masked by the effects of male competition or of attempts by males to constrain female choice.
