体毛染色结合臂环的标记技术在犬蝠室内行为研究中的应用

动物行为观察中个体识别是非常重要的。而现有对蝙蝠的标记方法,如臂环和颈圈等并不能满足室内红外线摄像头下识别个体进行行为观察的需要。本文采用体毛染色和臂环相结合的方法对犬蝠(Cynopterus sphinx)进行标记,可在室内行为观察中识别个体。     

Homing precision of roach Rutilus rutilus in Lake Arungen,Norway

Synopsis The present study tests the precision of repeat homing of roach, Rutilus rutilus, to two tributaries of a small Norwegian Lake, Årungen. A sample of 19 959 spawners was tagged or marked in the spawning area. After spawning the roach intermingled with other spawning demes in the lake. The year after marking, 2515 (12.6%) roach were recaptured during spawning in the five tributaries, 340 (13.5) of these were strayers. This straying is considerably larger than found in comparable autumn spawning species, but approximately the same as reported for other spring spawning species. The recapture rate was lower for females than for males, probably due to increased female mortality induced by the tagging manipulation.     

Electron Microscopy and Spectroscopical Studies on the Coloured Patches on the Wing of a Butterfly,Graphium sarpedon (Lepidoptera: Papillionidae) With Reference to Their Photobiological and Electrical Properties

The surface ultra-structural features of the coloured patches on the wing of a butterfly Graphium sarpedon have been studied with the help of scanning electron microscopy. Comparisons have been made between the dark brown area and the light green patches of the wing. A diffraction grating pattern with 15 lines per μm² with a uniform spacing of about 1 μm is present in the light green patches. A slightly coarser grating is present on the dark brown area, which constitutes the major portion of the wing. Sensilla chaetica was found on both the light green and dark brown area. A special type of sensilla trichodea with a big socket and some elongated projections were localized only on the light green patches. This region of the wing also contains some spherical structures with a diameter of 0.5 to 0.6 μm. The infra-red spectroscopy has revealed some differences in the nature and position of the peaks in the low-energy region in the dark brown area and the light green patches. The atomic absorption spectroscopy also shows qualitative as well as quantitative differences in the inorganic set up of the two regions. The electron spin resonance spectroscopy reveals the presence of a peak in the dark brown region only, indicating the presence of free radical in it. The differences observed in the ultra-structural and spectroscopical features, and also in the inorganic components of the two regions, are discussed in relation to their physical and physiological properties.     

Butterfly larvae reduce host plant survival in vicinity of alternative host species

Summary Mortality of an annual plant. Collinsia torreyi, was increased in the vicinity of Pedicularis semibarbata plants. This was a consequence of feeding by Euphydryas editha, a herbivore which feeds on both plant species. Mortality of C. torreyi was better predicted by distance from P. semibarbata than by density of C. torreyi. Since not all herbivores are monophagous, interactions involving distance and density effects on plant survival and on vegetational diversity need to be considered with respect to plant and herbivore communities. Some of the complexities of one predator, two prey systems are discussed.     

Programmed cell death at the periphery of the pupal wing of the butterfly,Pieris rapae

The outline of the adult wing of lepidopteran insects (butterflies and moths) emerges as a result of disappearance of a group of cells at the periphery of the pupal wing. Histological observation of the pupal wing of Pieris rapae showed that, just after apolysis of the wing epithelium from the pupal cuticle, there occurs a rapid and localized decrease of the number of cells at the periphery of the wing. This decrease occurs through cell death, which lasts 1–1.5 days at 20°C. Dying cells lose contact with the neighbouring cells and show condensation of chromatin and cytoplasm. They then appear to be phagocytosed by neighbouring epithelial cells or discharged through the basal surface of the epithelium into the lumen within the wing and taken up by phagocytes. Fragmentation of DNA in the nuclei was detected in the dead cells or their debris. These results indicate that programmed cell death in the lepidopteran wing proceeds through a mechanism closely similar to that of apoptosis in the vertebrate.     

Effects of predator removal on vertebrate prey populations: birds of prey and small mammals

We studied the effects of removal of breeding nomadic avian predators (the kestrel, Falco tinnunculus and Tengmalm's owl, Aegolius funereus) on small mammals (voles of the genera Microtus and Clethrionomys and the common shrew, Sorex araneus) during 1989–1992 in western Finland to find out if these predators have a regulating or limiting impact on their prey populations. We removed potential breeding sites of raptors from five manipulation areas (c. 3 km² each), whereas control areas had nest-boxes in addition to natural cavities and stick-nests. Densities of small mammals were monitored by snap-trapping in April, June, and August, and densities of mammalian predators (the least weasel, Mustela nivalis nivalis, the stoat, M. erminea and the red fox, Vulpes vulpes) by snow tracking in early spring and late autumn. The yearly mean number of raptor breeding territories was 0.2–1.0 in reduction areas and 3.0–8.2 in control areas. Breeding raptors alone did not regulate prey populations in the long term, but probably caused short-term changes in the population dynamics of both the main prey, the sibling vole (Microtus rossiaemeridionalis) and an alternative prey (the common shrew). The densities of an alternative prey, the bank vole (Clethrionomys glareolus) decreased in raptor reduction areas, most likely due to increased least weasel predation pressure in the absence of breeding avian predators.     

Does avian predation risk depress reproduction of voles?

Reproductive output and the growth of captive voles were quantified under high and low avian predation risk in a semi-natural experiment. Voles were exposed to Eurasian kestrels (Falco tinnunculus), the main avian predator of vole species studied (Clethrionomys glareolus, Microtus agrestis and M. rossiaemeridionalis). Vole pairs were housed in cages settled under nest-boxes occupied by breeding kestrels or in control cages settled under empty nest-boxes for 2 weeks. The experiment was conducted in mid-summer when kestrels had half-grown nestlings, because in that time hunting adults and begging nestlings produce noise and scats which may indicate significant predation threat to voles housed underneath the nest-boxes. The risk of kestrel predation did not have any obvious impact on pregnancy rates, mean litter sizes, or growth rates of kestrel-exposed voles compared with control voles studied. These results indicate that the risk of avian predation does not depress the reproductive investment of voles. Received: 3 November 1997 / Accepted: 16 February 1998     

Variation in predation pressure as a mechanism underlying differences in numerical abundance between populations of the poeciliid fish Heterandria formosa

We explored whether a variation in predation and habitat complexity between conspecific populations can drive qualitatively different numerical dynamics in those populations. We considered two disjunct populations of the least killifish, Heterandria formosa, that exhibit long-term differences in density, top fish predator species, and dominant aquatic vegetation. Monthly censuses over a 3-year period found that in the higher density population, changes in H. formosa density exhibited a strong negative autocorrelation structure: increases (decreases) at one census tended to be followed by decreases (increases) at the next one. However, no such correlation was present in the lower density population. Monthly census data also revealed that predators, especially Lepomis sp., were considerably more abundant at the site with lower H. formosa densities. Experimental studies showed that the predation by Lepomis gulosus occurred at a much higher rate than predation by two other fish and two dragonfly species, although L. gulosus and L. punctatus had similar predation rates when the amount of vegetative cover was high. The most effective predator, L. gulosus, did not discriminate among life stages (males, females, and juveniles) of H. formosa. Increased predation rates by L. gulosus could keep H. formosa low in one population, thereby eliminating strong negative density-dependent regulation. In support of this, changes in H. formosa density were positively correlated with changes in vegetative cover for the population with a history of lower density, but not for the population with a history of higher density. Our results are consistent with the hypothesis that the observed differences among natural populations in numerical abundance and dynamics are caused in part by the differences in habitat complexity and the predator community.     

Proximate determinants of telomere length in sand lizards (Lacerta agilis)

Telomeres are repeat sequences of non-coding DNA that cap the ends of chromosomes and contribute to their stability and the genomic integrity of cells. In evolutionary ecology, the main research target regarding these genomic structures has been their role in ageing and as a potential index of age. However, research on humans shows that a number of traits contribute to among-individual differences in telomere length, in particular traits enhancing cell division and genetic erosion, such as levels of free radicals and stress. In lizards, tail loss owing to predation attempts results in a stress-induced shift to a more cryptic lifestyle. In sand lizard (Lacerta agilis) males, telomere length was compromised by tail regrowth in a body size-related manner, so that small males, which already exhibit more cryptic mating tactics, were less affected than larger males. Tail regrowth just fell short of having a significant relationship with telomere length in females, and so did age in males. In females, there was a significant positive relationship between age and telomere length. We conclude that the proximate effect of compromised antipredation and its associated stress seems to have a more pronounced effect in males than in females and that age-associated telomere dynamics differ between the sexes.     

Determinants of spatial distribution in a population of the subalpine butterfly Oeneis chryxus

Summary This paper describes temporally varying determinants of the spatial distribution of adults in an insect population and the relationship between that distribution and the mating system. Male Oeneis chryxus butterflies were distributed nonrandomly throughout a sloping Colorado meadow divided horizontally by a dirt road into an upper and lower slope. Over an eight-year period of intensive study, the proportion of males located on the road, the upper slope, and the lower slope varied as a function of population size and sex ratio. In each year, more than half of the male population aggregated on sections of the road in a distinct and recurring pattern that was not correlated with the distribution of any food resource or thermal regime. Females were usually extremely scarce and not distributed in any pattern apparent from the few observations of them. Areas densely occupied by males were associated with visual landmarks. We hypothesize that the male distribution is determined by a pattern of movement of receptive females toward these landmarks. The road offers a thermally favorable environment with an unobstructed view in which to await the passage of scarce females. The mating system in this population has several lek-like features and supports the prediction that landmark mating is a favored strategy under conditions of female scarcity and wide dispersal of resources.     

Foraging patterns of voles at heterogeneous avian and uniform mustelid predation risk

Temporal variation of antipredatory behavior and a uniform distribution of predation risk over refuges and foraging sites may create foraging patterns different from those anticipated from risk in heterogenous habitats. We studied the temporal variation in foraging behavior of voles exposed to uniform mustelid predation risk and heterogeneous avian predation risk of different levels induced by vegetation types in eight outdoor enclosures (0.25 ha). We manipulated mustelid predation risk with weasel presence or absence and avian predation risk by reducing or providing local cover at experimental food patches. Foraging at food patches was monitored by collecting giving-up densities at artificial food patches, overall activity was automatically monitored, and mortality of voles was monitored by live-trapping and radiotracking. Voles depleted the food to lower levels in the sheltered patches than in the exposed ones. In enclosures with higher avian predation risk caused by lower vegetation height, trays were depleted to lower levels. Unexpectedly, voles foraged in more trays and depleted trays to lower levels in the presence of weasels than in the absence. Weasels match their prey's body size and locomotive abilities and therefore increase predation risk uniformly over both foraging sites and refuge sites that can both be entered by the predator. This reduces the costs of missing opportunities other than foraging. Voles changed their foraging strategy accordingly by specializing on the experimental food patches with predictable returns and probably reduced their foraging in the matrix of natural food source with unpredictable returns and high risk to encounter the weasel. Moreover, after 1 day of weasel presence, voles shifted their main foraging activities to avoid the diurnal weasel. This behavior facilitated bird predation, probably by nocturnal owls, and more voles were killed by birds than by weasels. Food patch use of voles in weasel enclosures increased with time. Voles had to balance the previously missed feeding opportunities by progressively concentrating on artificial food patches.     

Estimation of density,survival rate and dilution rate ofMecostethus magister (Orthoptera: Acrididae) populations by the mark and recapture method

Population Ecology -     

Reduction of Banana Weevil Populations Using Different Formulations of the Entomopathogenic Fungus Beauveria bassiana

One of the major constraints for banana production in Uganda is the banana weevil, Cosmopolites sordidus (Germar), (Coleoptera: Curculionidae). Investigations were carried out to evaluate the efficacy of maize, soil-based and oil formulations of an indigenous isolate of Beauveria bassiana for the control of the banana weevil. Weekly trapping of weevils over a 9-month monitoring period showed significant reduction in unmarked and marked weevil population in B. bassiana treated plots. Application of maize formulation at 2 ×10 15 conidia ha -1 proved most effective, reducing the weevil populations by 63-72% within 8 weeks after a single application. The soil based formulation at 2 ×10 14 conidia ha -1 was intermediate while the oil formulation at 6 ×10 15 conidial ha -1 was least effective. Trapping efficiency declined in B. bassiana treated and untreated banana plots but was greatest in the latter.     

Induction and costs of tail spine elongation in Daphnia hyalina×galeata: reduction of susceptibility to copepod predation

1. Seasonal field data showed a positive correlation between the tail spine length of Daphnia hyalina × galeata and the density of the copepod Acanthocyclops robustus . Laboratory experiments were designed to assess the mechanisms underlying the induction of tail spine elongation and to test whether this morphology reduced predation on Daphnia juveniles.
2. Both the elongated tail spine morph and control spine morph produced progeny with elongated tail spine when exposed to copepods. Instar increments, calculated from individual body length, showed that individual growth decreased in the presence of copepods. This decrease in individual growth was less pronounced in spined morphs relative to control morphs.
3. Copepods exhibited significantly higher feeding rates on control morph juveniles compared to elongated tail spine morph juveniles.
4. All Daphnia matured at instar 5 even though the control morph neonates took 24–30 more hours to mature in the presence of copepods than in the absence of copepods. Enlarged body and spine lengths of progeny coincided with reduced progeny number during the first six reproductive instars. The disadvantage of the reduced offspring number produced per female was balanced by enhanced survivorship of progeny subjected to copepod predation.     

A simulation study of mutations in the genetic regulatory hierarchy for butterfly eyespot focus determination

The color patterns on the wings of butterflies have been an important model system in evolutionary developmental biology. A recent computational model tested genetic regulatory hierarchies hypothesized to underlie the formation of butterfly eyespot foci [Evans, T.M., Marcus, J.M., 2006. A simulation study of the genetic regulatory hierarchy for butterfly eyespot focus determination. Evol. Dev. 8, 273-283]. The computational model demonstrated that one proposed hierarchy was incapable of reproducing the known patterns of gene expression associated with eyespot focus determination in wild-type butterflies, but that two slightly modified alternative hierarchies were capable of reproducing all of the known gene expressions patterns. Here we extend the computational models previously implemented in Delphi 2.0 to two mutants derived from the squinting bush brown butterfly (Bicyclus anynana). These two mutants, comet and Cyclops, have aberrantly shaped eyespot foci that are produced by different mechanisms. The comet mutation appears to produce a modified interaction between the wing margin and the eyespot focus that results in a series of comet-shaped eyespot foci. The Cyclops mutation causes the failure of wing vein formation between two adjacent wing-cells and the fusion of two adjacent eyespot foci to form a single large elongated focus in their place. The computational approach to modeling pattern formation in these mutants allows us to make predictions about patterns of gene expression, which are largely unstudied in butterfly mutants. It also suggests a critical experiment that will allow us to distinguish between two hypothesized genetic regulatory hierarchies that may underlie all butterfly eyespot foci.