Relapse may have evolved in malaria as a mechanism to avoid suppression by more virulent species in mixed infections, thereby increasing transmission opportunities. Later evolution of long latency in Plasmodium vivax was a necessary adaptation as early hominins moved to colder areas with shorter mosquito breeding seasons. Genetic diversity was maintained through heterologous hypnozoite activation.
No abstract is provided for this article.
Single suture craniosynostosis (SSC) and isolated cleft palate (ICP) in non-Apert syndrome patients rarely occur together. Management includes airway optimization, timing surgery appropriately, and assessing both cranial vault aesthetics and speech outcomes. The aim of this study was to compare treatment pathways and outcomes in patients with both conditions to standard treatment for these conditions in isolation.Patient hospital medical records were retrospectively reviewed for demographic data, timing of surgery, aesthetic outcome (using the Whitaker grading system for head shape), and speech outcome (from speech therapy records of general development and speech assessment).Six patients with SSC and ICP were identified over an 18-year period. Cranial surgery was performed between 4 and 16 months and cleft surgery between 6 and 34 months of age in all cases. Documentation of cleft surgery and genetic testing was not available for 1 patient. One patient with hemi-palatal absence had an obturator inserted at 34 months. Two patients were found to have Fragile X and Emanuel syndrome, respectively.No increased perioperative airway risk was highlighted in any case. Four cases were designated Whitaker grade 1, 1 case was designated grade 2, and 1 case was not graded as no cranial surgery was performed. Half of the patients had general and speech developmental delay, while the other half demonstrated no signs of developmental delay.Examination of 6 patients with SSC and ICP suggests the presence of both conditions does not adversely impact management or outcome for each condition, or increase perioperative risk.
Over the last three decades, research in behavioural ecology has focussed on the choices that individuals make over food (Stephens/Krebs 1986), mating opportunities (Andersson 1995), parental care (Clutton-Brock 1991) and cooperation with other group members (Brown 1987; Clutton-Brock/Parker 1995b). Yet, in social species, most individuals rarely have the opportunity to choose freely because their options are constrained by the behaviour of dominant animals (Clutton-Brock/Parker 1995b). Coercion is common in many contexts where conflicts of interest occur, but is particularly important in interactions between the sexes, where it often has substantial costs to females. In a recent paper (1993), Smuts and Smuts argue that sexual coercion should be regarded as a third form of sexual selection, separate from intrasexual competition and intersexual mate choice. Whether or not this is accepted, it is clear that sexual coercion has not received the attention that it deserves.
Summary Three patients experienced complex formed hallucinations during progressive visual failure from eye disease. The hallucinations began abruptly, were brightly coloured stereotyped figures, animals or objects, and appeared to be provoked by light. As blindness progressed the clarity, frequency and duration of the hallucinations faded. The patients had no abnormalities other than their eye disease, which in two cases was macula degeneration, and choroideraemia in the third.
Although global morbidity and mortality have decreased substantially, malaria, a parasite infection of red blood cells, still kills roughly 2000 people per day, most of whom are children in Africa. Two factors largely account for these decreases; increased deployment of insecticide-treated bednets and increased availability of highly effective artemisinin combination treatments. In large trials, parenteral artesunate (an artemisinin derivative) reduced severe malaria mortality by 22·5% in Africa and 34·7% in Asia compared with quinine, whereas adjunctive interventions have been uniformly unsuccessful. Rapid tests have been an important addition to microscopy for malaria diagnosis. Chemopreventive strategies have been increasingly deployed in Africa, notably intermittent sulfadoxine–pyrimethamine treatment in pregnancy, and monthly amodiaquine–sulfadoxine–pyrimethamine during the rainy season months in children aged between 3 months and 5 years across the sub-Sahel. Enthusiasm for malaria elimination has resurfaced. This ambitious but laudable goal faces many challenges, including the worldwide economic downturn, difficulties in elimination of vivax malaria, development of pyrethroid resistance in some anopheline mosquitoes, and the emergence of artemisinin resistance in Plasmodium falciparum in southeast Asia. We review the epidemiology, clinical features, pathology, prevention, and treatment of malaria.
This chapter reviews our understanding of the adaptive significance of variation in the length of incubation and gestation and of patterns of lactation in endotherms. Though similar questions might usefully be asked about incubation and gestation periods in invertebrates, fish, reptiles, and amphibia, questions of this kind have been more frequently asked about birds and mammals (see Lack 1960; Eisenberg 1981), and our understanding of the extent and distribution of interspecific differences in all three parameters is more advanced in these than in other groups of animals.
In cooperatively breeding species where rearing effort is shared among multiple group members, increases in group size typically reduce average per capita contributions to offspring care by all group members (load-lightening) but it is not known how changes in group size affect the distribution of workload among group members. The socioeconomic collective action theory suggests that, in larger groups, the incentives for free riding are stronger, leading to greater inequalities in work division among group members. Here, we use the Gini index to measure inequality at the group level in the contributions of helpers to three different cooperative behaviours (babysitting, pup-provisioning and raised guarding) in groups of varying size in wild Kalahari meerkats ( Suricata suricatta ). In larger groups, inequality in helpers' contributions to cooperative activities and the frequency of free riding both increased. Elevated levels of inequality were generated partly as a result of increased differences in contributions to cooperative activities between helpers in different sex and age categories in larger groups. After controlling for the positive effect of group size on total provisioning, increasing levels of inequality in contributions were associated with reductions in total pup-provisioning conducted by the group. Reductions in total pup-provisioning were, in turn, associated with reductions in the growth and survival of pups (but pup growth and survival were not directly affected by inequality in provisioning). Our results support the prediction of collective action theory described above and show how the Gini index can be used to investigate the distribution of cooperative behaviour within the group.
Darwin developed the theory of sexual selection to account for the evolution of weaponry, ornamentation and other secondary sexual characters that are commonly more developed in males and which appeared unlikely to contribute to survival. He argued that these traits had evolved either through intrasexual competition between males to monopolize access to females or through consistent female preferences for mating with superior partners. Since 1871, a substantial body of research has confirmed his explanation of the evolution of secondary sexual characters in males, although sex differences in reproductive behaviour are more diverse and the evolutionary mechanisms responsible for them are more complex than was initially recognized. However, secondary sexual characters are also widespread in females but, as yet, their evolution and distribution have received relatively little attention from evolutionary biologists. Here, I suggest that the mechanisms responsible for the evolution of secondary sexual characters in females are similar to those operating in males and include intrasexual competition between females for breeding opportunities, male mating preferences and female competition to attract mates. Unlike males, females often compete more intensely for resources necessary for successful reproduction than for access to mating partners and the development of secondary sexual characters in females may be limited by costs to fecundity rather than to survival.
