抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Beginning with Emlen (1966) and MacArthur and Pianka (1966) and extending through the last ten years, several authors have sought to predict the foraging behavior of animals by means of mathematical models. These models are very similar,in that they all assume that the fitness of a foraging animal is a function of the efficiency of foraging measured in terms of some "currency" (Schoener, 1971) -usually energy- and that natural selection has resulted in animals that forage so as to maximize this fitness. As a result of these similarities, the models have become known as "optimal foraging models"; and the theory that embodies them, "optimal foraging theory." The situations to which optimal foraging theory has been applied, with the exception of a few recent studies, can be divided into the following four categories: (1) choice by an animal of which food types to eat (i.e., optimal diet); (2) choice of which patch type to feed in (i.e., optimal patch choice); (3) optimal allocation of time to different patches; and (4) optimal patterns and speed of movements. In this review we discuss each of these categories separately, dealing with both the theoretical developments and the data that permit tests of the predictions. The review is selective in the sense that we emphasize studies that either develop testable predictions or that attempt to test predictions in a precise quantitative manner. We also discuss what we see to be some of the future developments in the area of optimal foraging theory and how this theory can be related to other areas of biology. Our general conclusion is that the simple models so far formulated are supported are supported reasonably well by available data and that we are optimistic about the value both now and in the future of optimal foraging theory. We argue, however, that these simple models will requre much modification, espicially to deal with situations that either cannot easily be put into one or another of the above four categories or entail currencies more complicated that just energy.

Citation classic - optimal foraging - a selective review of theory and tests

There is growing recognition of the important roles played by predators in regulating ecosystems and sustaining biodiversity. Much attention has focused on the consequences of predator-regulation of herbivore populations, and associated trophic cascades. However apex predators may also control smaller 'mesopredators' through intraguild interactions. Removal of apex predators can result in changes to intraguild interactions and outbreaks of mesopredators ('mesopredator release'), leading in turn to increased predation on smaller prey. Here we provide a review and synthesis of studies of predator interactions, mesopredator release and their impacts on biodiversity. Mesopredator suppression by apex predators is widespread geographically and taxonomically. Apex predators suppress mesopredators both by killing them, or instilling fear, which motivates changes in behaviour and habitat use that limit mesopredator distribution and abundance. Changes in the abundance of apex predators may have disproportionate (up to fourfold) effects on mesopredator abundance. Outcomes of interactions between predators may however vary with resource availability, habitat complexity and the complexity of predator communities. There is potential for the restoration of apex predators to have benefits for biodiversity conservation through moderation of the impacts of mesopredators on their prey, but this requires a whole-ecosystem view to avoid unforeseen negative effects. 'Nothing has changed since I began. My eye has permitted no change. I am going to keep things like this.' From 'Hawk Roosting', by Ted Hughes.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1461-0248.2009.01347.x

Predator interactions, mesopredator release and biodiversity conservation

The Vegetation of South Africa, Lesotho and Swaziland

Walker's Mammals of the World, 4th Edition, Ronald M. Nowak, John L. Paradiso. The Johns Hopkins University Press, Baltimore, Maryland (1983), 1xi, +1-568 (Vol. I), xxv+569-1362 (Vol. II). Price $65.00

For terrestrial carnivores, scat analysis is the technique most often used to deter- mine diets. Various methods of interpreting scat-analysis data exist; however, little is known about how the choice of method affects the results. 2. We reviewed 50 scat-analysis papers to assess the range of methods currently used. Furthermore, we used a large data set from cape fox Vulpes chama and black-backed jackal Canis mesomelas scats to compare 11 scat-analysis methods. Techniques tested included five biomass calculation methods, four frequency of occurrence methods, one method that estimated volume in scats, and another that estimated mass of food items in scats. 3. Frequency of occurrence methods were used in 94% of reviewed papers, and in 50% of papers they were the sole methods used. However, we conclude that fre- quency of occurrence has the least ecological significance and results can be mis- leading. Although biomass calculations probably provide the best approximation to true diets, only 23% of reviewed papers used suitable biomass calculation methods when models were available for the study species. 4. Analysis of fox and jackal scats showed that there were significant differences among methods when calculating percent diet composition and niche breadth. Additionally, dietary overlap between species differed considerably among the methods (range of R0 = 0.29-0.79). We conclude that the choice of method can have a significant impact on the results of dietary analysis, and can lead to very different conclusions about a species' ecology. 5. The best approximation of the true diet can be obtained by using a biomass calculation model that was developed for the same species, or for a closely related species with a similar food spectrum. When no such model is available, either the volume or mass of diet components in the scats should be used. To document rare food items, frequency of occurrence data could also be given.

A comparison and critique of different scat‐analysis methods for determining carnivore diet

The leopard's (Panthera pardus) broad geographic range, remarkable adaptability, and secretive nature have contributed to a misconception that this species might not be severely threatened across its range. We find that not only are several subspecies and regional populations critically endangered but also the overall range loss is greater than the average for terrestrial large carnivores. To assess the leopard's status, we compile 6,000 records at 2,500 locations from over 1,300 sources on its historic (post 1750) and current distribution. We map the species across Africa and Asia, delineating areas where the species is confirmed present, is possibly present, is possibly extinct or is almost certainly extinct. The leopard now occupies 25-37% of its historic range, but this obscures important differences between subspecies. Of the nine recognized subspecies, three (P. p. pardus, fusca, and saxicolor) account for 97% of the leopard's extant range while another three (P. p. orientalis, nimr, and japonensis) have each lost as much as 98% of their historic range. Isolation, small patch sizes, and few remaining patches further threaten the six subspecies that each have less than 100,000 km(2) of extant range. Approximately 17% of extant leopard range is protected, although some endangered subspecies have far less. We found that while leopard research was increasing, research effort was primarily on the subspecies with the most remaining range whereas subspecies that are most in need of urgent attention were neglected.

https://www.panthera.org/cms/sites/default/files/peerj_1974.pdf

Leopard (Panthera pardus) status, distribution, and the research efforts across its range

Several nonlethal methods have been developed to determine the stomach contents of fish, including gastroscopes, tubes, stomach suction, stomach flushing, emetics, forceps, and chronic fistulas. By reviewing the literature on this subject, we found that the effectiveness (ability to remove all stomach contents) of the different methods depends on size, age, species of fish, and the size of the food items in the stomach. Overall, various methods of stomach flushing were the most effective method of recovering stomach items from a variety of fishes. Mechanized pressure appeared to be the most efficient method of stomach flushing for most large fishes. The use of syringes allowed stomach flushing to be performed on most young and small fishes. The use of tubes and stomach suctions, much simpler and less expensive methods than stomach flushing, were nearly as effective for some fishes such as black bass (Micropterus spp.) and salmonids.

/pdf/nonlethal-methods-of-examining-fish-stomach-contents-hphf6rh799.pdf

Nonlethal Methods of Examining Fish Stomach Contents

The distribution of swift foxes (Vulpes velox) in the western Great Plains has been dramatically reduced since historical times. Because coyotes (Canis latrans) have been identified as the main cause of mortality in swift fox populations, we studied the impacts of coyotes on swift foxes in northwestern Texas, USA. We radiomarked and monitored 88 swift foxes and 29 coyotes at 2 study sites from 1998 to 2000. On site 1, coyotes had relatively high abundance (41 ± 6.8 scats/2 km) and survival (0.90), whereas swift foxes had low survival (0.47), low density (0.24-0.31 foxes/km 2 ), and low recruitment (0.25 young/adult), and killings by coyotes (n = 8) were the major cause of death. On site 2, coyotes had relatively low abundance (19 ± 4.9 scats/2 km) and survival (0.54) due to greater human persecution, whereas swift foxes had relatively high survival (0.69), high density (0.68-0.77 foxes/km 2 ), and high recruitment (1.3 young/adult), and few (n = 2) were killed by coyotes. Our initial results -. suggested that swift foxes benefited from lower coyote numbers. To test this hypothesis, we removed 227 coyotes on site 1 during the final year of our study. Subsequently, coyote abundance decreased (18 ± = 4.5 tcats/2 km), whereas swift foxes had increased survival (0.63), increased density (0.68 foxes/km 2 ), arid increased recruitment (1.2 young/adult), and few (n = 3) were killed by coyotes. All parameters remained consistent on site 2. Our results indicate that coyotes can suppress swift fox populations, and that reductions in coyote numbers can change a swift fox population from a sink to a source.

https://www.jstor.org/stable/pdfplus/3802773.pdf

Impacts of coyotes on swift foxes in Northwestern Texas

We radio-tracked 10 coyotes (Canis latrans) from April 1996 to March 1998 on Fort Riley Military Reserva- tion, Kansas, to compare movements, habitat use, and survival between resident (breeders and pack associates) and transient coyotes. Home ranges of resident coyotes were mutually exclusive, whereas those of transient coyotes over- lapped the home ranges of other coyotes. Excursions from home ranges were made by all resident pack associates but not by resident breeders. Grassland habitats were used more than expected by resident coyotes but less than expected by transients. Woodlands and cultivated lands were used more than expected by transients. Transient coyotes used areas between the home ranges of resident family groups. Annual survival rates were higher for resident than for transient coyotes. Avoidance of resident coyotes by transient coyotes may explain differences in space and habitat use by coyotes. Resume : Nous avons suivi 10 Coyotes (Canis latrans) par radio-telemetrie, d'avril 1996 a mars 1998, dans la reserve militaire de Fort Riley, Kansas, pour comparer les deplacements, l'utilisation de l'habitat et la survie chez les coyotes residants (les reproducteurs et les individus associes a la meute) et les coyotes de passage. Les domaines des coyotes residants etaient mutuellement exclusifs, alors que les domaines des coyotes de passage chevauchaient les domaines d'autres coyotes. Tous les coyotes associes a la meute et residants s'aventuraient hors de leur domaine, mais pas les reproducteurs residants. Les coyotes residants frequentaient les prairies plus que prevu, alors que les coyotes de pas - sage les utilisaient moins que prevu, mais ils frequentaient les boises et les terres cultivees plus que prevu. Les coyotes de passage utilisaient egalement des zones entre les domaines de groupes familiaux residants. Les taux annuels de survie etaient plus eleves chez les coyotes residants que chez les coyotes de passage. Les coyotes de passage evitent les coyotes residants, ce qui peut expliquer les differences dans les choix d'habitats chez les deux groupes.

Jan F. Kamler

Papers

A comparison and critique of different scat‐analysis methods for determining carnivore diet

Leopard (Panthera pardus) status, distribution, and the research efforts across its range

Nonlethal Methods of Examining Fish Stomach Contents

Impacts of coyotes on swift foxes in Northwestern Texas

Space and habitat use by resident and transient coyotes.