The responses of wild jacamars (Galbula ruficauda,Galbulidae) to aposematic,aposematic and cryptic,and cryptic butterflies in central Brazil

1. This article reports the responses of wild, adult jacamars to butterflies with distinct coloration types in central Brazil. Fully aposematic species, i.e. those exhibiting bright and/or contrasting colours on both wing surfaces (= A/A), were predominantly sight‐rejected by birds and, with one exception, the few butterflies attacked and captured were taste‐rejected afterwards. 2. Aposematic and cryptic butterflies, i.e. those exhibiting bright and/or contrasting colours on the upper and cryptic colours on the underwings (= A/C) were sight‐rejected while flying, when they show their conspicuous colours to predators. This suggests that birds associate butterfly colours with their difficulty of capture, as in the case of Morpho and several Coliadinae species. These butterflies, however, were heavily attacked at rest, when they are cryptic. 3, Fully cryptic butterflies, i.e. those exhibiting cryptic colours on both wing surfaces (= C/C) did not elicit sight rejections by birds. Comparisons involving the number of attacks and the capture success of flying and resting individuals showed no significant differences in species more frequently observed like some cracker butterflies (Hamadryas feronia and H. februa) and Taygetis laches. Compared with the A/C Coliadinae, these butterflies showed a lesser, although not significantly different, ability to escape while flying, but a greater and significantly different ability to escape while at rest. 4, A hunting tactic of jacamars, which consists of following flying A/C and C/C butterflies on sight, and waiting until they perch to locate and attack them, is described for the first time.     

Butterfly visual characteristics and ontogeny of responses to butterflies by a specialized tropical bird

The responses of two adult and three hand-reared, naive young rufous-tailed jacamars (Galbula ruficauda) to local butterflies were studied in feeding experiments. Four behavioural characteristics distinguish jacamars from other less specialized avian predators: (1) Exposed to butterflies for the first time, naive young jacamars would attack butterflies without showing signs of inhibition. Unacceptable butterflies, once captured, were taste-rejected quickly, and most survived the sampling. The few presumably unacceptable butterflies consumed by the birds were not observed to cause vomiting. (2) After gaining some familiarity with butterflies, young birds, like the adults, developed a reluctance to attack. They visually rejected certain classes of butterflies, often failing to attack them during an entire four-hour feeding trial. However, occasional attacks were made on butterflies in these ‘rejected’ classes. When this did occur, the insects proved to be actually easier to catch than those that were more often attacked. Once captured, however, the majority of these butterflies were taste-rejected. (3) For a given butterfly species, most individuals were either consumed or rejected. Thus, each species could be clearly classified as either acceptable or unacceptable to the jacamars. This consistency in jacamar responses resulted in a bimodal acceptability distribution of sympatric butterflies. (4) Young jacamars were capable of rapid associative learning and their responses were closely associated with butterfly visual characteristics in which colour pattern, flight behaviour, and morphology were also closely correlated. Thus, a single butterfly morphological parameter termed body shape (body length/thoracic diameter ratio) can adequately predict the feeding responses of jacamars. Visually detectable traits associated with butterflies possessing chemical defences may represent a balance between the need to signal unambiguously to specialized and/or experienced predators and the need to escape attacks by generalized and/or opportunistic predators. Since the proportion of specialized predators is higher in the tropical rainforest than in other habitat types, we expect greater divergence of morphological and behavioural characteristics between palatable and unpalatable butterflies in rainforest habitats.     

Biogeography of milkweed butterflies (Nymphalidae: Danainae) and mimetic patterns on tropical Paciflc archipelagos

Distributions of danaine butterfly species and associated mimetic patterns were compared among fifteen archipelagos of the tropical Pacific Ocean, and within five major archipelagos (the Bismarcks, Fiji, East and West Solomon Islands, and Vanuatu). Using both simple and stepwise linear regression analysis, variation in the total number of danaine species and number of mimetic patterns was assessed with respect to island size, isolation and elevation. Relative to interarchipelago distributions, the distribution of danaine species and number of mimetic patterns on islands within archipelagos exhibited less dependence upon interisland distance and island area. Geographical features influencing the number of mimetic patterns were similar to those of danaines as a whole. Analysis of residuals from stepwise linear regression suggested that factors influencing danaine distributions were different from those for non-danaine butterflies. This result is consistent with the hypothesis of enhancement of danaine species establishment through Müllerian mimicry, although other factors such as host plant availability and similar habitat use may also be important.     

Importance of colour in the reaction of passerine predators to aposematic prey: experiments with mutants of Pyrrhocoris apterus (Heteroptera)

Persistent questions concerning the warning coloration of unpalatable insects address whether the bright aposematic colour itself or its combination with a species-specific dark pattern is the key factor in their protection against insectivorous birds, and how chromatic polymorphism originates and is maintained in aposematics. In the present study, these questions were tested experimentally, using the birds Parus major , Parus caeruleus , Erithacus rubecula , and Sylvia atricapilla as predators, and chromatically polymorphic firebug Pyrrhocoris apterus : red wild form, white, yellow, and orange mutants (all four of them with the same black melanin pattern, the mutants differing in colour of pteridine pigments only) and the nonaposematic brown-painted wild form as prey. The results show that a specific colour is essential for the birds to recognize the specific aposematic prey; the melanin pattern is not sufficient. White mutants were no better protected than nonaposematic firebugs; red wild-type and orange mutants were equally well protected against all bird species; and the reaction of birds to yellow mutants was species-specific. An evolutionary scenario of 'recurrent recessive mutations' is formulated to explain the origin of colour polymorphism in some aposematics.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 143–153.     

A review of the diversity and evolution of photonic structures in butterflies, incorporating the work of John Huxley (The Natural History Museum, London from 1961 to 1990)

The photonic structures of butterfly wings are among the most anatomically diverse of all those in nature, giving rise to an unrivalled display of structural colours. These have recently become the focus of research by workers in a variety of disciplines, stimulated by their potential applications to technology ('biomimetics'). This interest, together with the discovery of unpublished electron micrographs taken by the late Dr John Huxley (Natural History Museum, London), prompted this review of butterfly photonics in general. The current work provides a synopsis of the literature to date, covering the diversity and evolution of these optical structures and incorporating Huxley's work, which represents an important biomimetic and evolutionary database on its own. This review deals with butterfly photonic devices according to the parts of the butterfly scales on which they occur. In this way, the information is ripe for evolutionary study.     

Presence of a cerebral factor showing summer-morph-producing hormone activity in the brain of the seasonal non-polyphenic butterflies Vanessa cardui, V. indica and Nymphalis xanthomelas japonica (Lepidoptera: Nymphalidae)

Three species of nymphalid butterflies, Vanessa cardui, V. indica and Nymphalis xanthomelas japonica , do not exhibit seasonal polyphenism in wing coloration. To determine whether seasonal non-polyphenic butterflies possess a cerebral factor affecting wing coloration, we used a Polygonia c-aureum female short-day pupal assay for detection of summer-morph-producing hormone (SMPH) activity in P. c-aureum. When 2% NaCl extracts of 25 brain-equivalents prepared from the pupal brains of V. cardui, V. indica or N. xanthomelas japonica were injected into Polygonia female short-day pupae, all recipients developed into summer-morph adults with dark-yellow wings, and the average grade score (AGS) of summer morphs showing SMPH activity was 3.8, 3.7 and 4.0, respectively. In contrast, when acetone or 80% ethanol extracts prepared from pupal brains were injected into Polygonia pupae, all recipients developed into autumn-morph adults with a dark-brown coloration and each exhibited an AGS of less than 0.5. Our results indicate that a cerebral factor showing SMPH activity is present in the pupal brain of seasonal non-polyphenic nymphalid butterflies, suggesting that a SMPH and cerebral factor showing SMPH activity occur widely among butterfly species. This finding will improve our understanding of the presence of cerebral factors showing interspecific actions of SHPH.     

Body size as a primary determinant of ecomorphological diversification and the evolution of mimicry in the lampropeltinine snakes (Serpentes: Colubridae)

Evolutionary correlations between functionally related character suites are expected as a consequence of coadaptation due to physiological relationships between traits. However, significant correlations may also exist between putatively unrelated characters due to shared relationships between those traits and underlying variables, such as body size. Although such patterns are often dismissed as simple body size scaling, this presumption may overlook important evolutionary patterns of diversification. If body size is the primary determinant of potential diversity in multiple unrelated characters, the observed differentiation of species may be governed by variability in body size, and any biotic or abiotic constraints on the diversification thereof. Here, we demonstrate that traits related to both predatory specialization (gape and diet preference) and predatory avoidance (the development of Batesian mimicry) are phylogenetically correlated in the North American snake tribe Lampropeltini. This is apparently due to shared relationships between those traits and adult body size, suggesting that size is the primary determinant of ecomorphological differentiation in the lampropeltinines. Diversification in body size is apparently not linked to climatic or environmental factors, and may have been driven by interspecific interactions such as competition. Additionally, we find the presence of a ‘key zone’ for the development of both rattle‐ and coral snake mimicry; only small snakes feeding primarily on ectothermic prey develop mimetic colour patterns, in or near the range of venomous model species.     

獐(Hydropotes inermis)的警戒行为模式及逃跑起始距离的适应性变化

为了掌握獐的警戒行为特征并为重引入项目提供管理依据,以人为干扰源观察獐的警戒反应,发现其警戒模式包括听 (listen) 或扫视 (scan) ,盯视 (stare) ,走开 (walk away) ,跑开 (run away),吼叫 (bark) 和压脖 (stretch) 。利用逃跑起始距离对上海松江圈养 (自由采食) 獐、上海华夏圈养(人工饲喂) 獐和江苏盐城野生獐进行警戒性比较,得出：人工饲喂獐警戒性最小,野生獐警戒性最大。可通过野化训练提高人工饲喂獐的警戒性;人类活动、种群密度、围栏和区域面积可能影响獐的警戒性。     

The feeding behaviour of a deep-sea holothurian, Stichopus tremulus (Gunnerus) based on in situ observations and experiments using a Remotely Operated Vehicle

Using a Remotely Operated Vehicle (ROV) to deploy an in situ cage experiment incorporating fluorescent Luminophore particle tracers, the gut throughput time of the deposit feeding holothurian, Stichopus tremulus (Gunnerus) was determined as 23.73 h (S.D.±2.3). For a range of individuals examined at different depths (350-500 m) and locations, throughput times varied between 19 and 26 h irrespective of animal size or gut tract length. In situ video observations of feeding behaviour showed that this species uses fine oral papillae in a ‘sweeping’ motion to target particles on the seafloor. Following detection of a food source fine-branched digitate tentacles collect a large range of sediment fragments from the seabed. The main types of particles ingested include silica fragments (<20 >500 μm), pelagic foraminifera, benthic foraminifera, fine phytodetrital remains and occasional larger rock fragments (∼1 cm). Ingested sediment consisted mainly of very fine silica fragments (∼50 μm) accounting for over 50% of the total gut contents. Frame-by-frame video analysis revealed that the particle handling time (i.e. the time taken for a tentacle insertion and the subsequent collection of food) was found to be ∼54 s. Only 10 of the 20 feeding tentacles were simultaneously employed during feeding. Use of tentacles appeared to be in sequence, alternating between the reserve and active tentacles. Estimating the rate of movement over the seabed and the total effective capture area of each tentacle, the impact of this animal on the turnover and quality of surface sediment at this deepwater site is potentially substantial. The in situ experiments provided a significant improvement over previous methods used to investigate deep-sea deposit feeders and represent a useful concept for further in situ deep-sea research using an industrial ROV.     

Field and laboratory observations on the foraging and feeding techniques of blue tits (Parus caeruleus) and coal tits (P. ater) in relation to their habitats

I have tried to show (a) that results in the literature suggest that blue tits and coal tits survive better in their usual habitats of broad-leaved and conifer woods respectively; (b) that the higher mortality in the ‘wrong’ habitat may be attributed at least in part to an inability to acquire an adequate supply of food; (c) from my own and other people's field observations, that wild coal tits and blue tits use different feeding techniques; (d) from my own laboratory experiments, that each species is ‘best’ at the feeding techniques which it in general uses in the wild, and also that each species prefers to use the feeding techniques at which it is ‘best’; (e) that the feeding techniques of coal tits may be adapted to exploit the type of food supply found in conifers, while those of blue tits may be adapted for feeding in broad-leaved trees.     

Laboratory observations on the vertical distribution of a tropical pelagic flatworm (Mesostoma sp.) in relation to satiation

Mesostoma sp., isolated from different lakes in Brazil, was taken to the laboratory and fed Moina sp. The vertical position of satiated and non-satiated individuals was monitored in 25 cm high columns exposed to natural sunlight. Phototactic responses were studied under standardised experimental conditions.Satiated individuals resided nearer to the bottom than non-satiated Mesostoma. Non-satiated individuals showed an irregular vertical distribution due to swimming behaviour, whereas satiated animals remained stationary.     

Field experiments on interactions between vertebrate predators and larval midges (Diptera: Chironomidae) in the littoral zone of a reservoir

Summary A field experiment was designed to test a frequent assumption in the literature that vertebrate predators (in this case, fish and turtles) are capable of regulating the seasonal abundance and diversity of benthic communities in the littoral zone of lentic environments. Effects of thermal effluents from a nuclear reactor on predator-prey relationships were also examined. Benthic samples were removed after each of three, 3-month test periods from 36 predator exclusion cages (4m²) and 36 control plots located along a thermal gradient in Par Pond, an 1,100 ha freshwater reservoir in the southeastern United States.Results of our field experiments provide little evidence to suggest that either a single keystone species or vertebrate predators as a group were capable of regulating the abundance, diversity or productivity of chironomids in Par Pond. The relationship between predator treatment and community response (changes in density and species richness) was generally unaffected by either plot location or temperature fluctuations. When data from caged and control plots were pooled, however, both location and water temperature individually had significant impacts on the chironomid community. Alternative hypotheses are proposed to explain the lack of regulatory control of the benthic community by individual species or guilds of predators.     

Field experiments on the ability of Arthrobotrys oligospora (Hyphomycetales) to reduce the number of larvae of Cooperia oncophora (Trichostrongylidae) in cow pats and surrounding grass

In field experiments, conducted on parasite-free grass plots in two consecutive summers, artificially prepared cow pats containing Cooperia oncophora eggs were inoculated with the nematode-trapping fungus Arthrobotrys oligospora. Numbers of infective C. oncophora larvae isolated from the pats as well as from the surrounding herbage were subject to an approximately ten-fold reduction as compared with numbers in fungus-free pats and herbage surrounding these. This reduction was undoubtedly a result of entrapment of the parasite larvae within the faecal pats.     

On the reliability of a simple method for scoring phenotypes to estimate heritability: A case study with pupal color in Heliconius erato phyllis, Fabricius 1775 (Lepidoptera, Nymphalidae)

In this paper, two methods for assessing the degree of melanization of pupal exuviae from the butterfly Heliconius erato phyllis, Fabricius 1775 (Lepidoptera, Nymphalidae, Heliconiini) are compared. In the first method, which was qualitative, the exuviae were classified by scoring the degree of melanization, whereas in the second method, which was quantitative, the exuviae were classified by optical density followed by analysis with appropriate software. The heritability (h(2)) of the degree of melanization was estimated by regression and analysis of variance. The estimates of h (2) were similar with both methods, indicating that the qualitative method could be particularly suitable for field work. The low estimates obtained for heritability may have resulted from the small sample size (n = 7-18 broods, including the parents) or from the allocation-priority hypothesis in which pupal color would be a lower priority trait compared to morphological traits and adequate larval development.     

A bioenergetic assessment of the influence of stocking practices on rainbow trout (Oncorhynchus mykiss) growth and consumption in a New Zealand lake

Summary

• 1 To investigate the carrying capacity and factors affecting growth of rainbow trout in Lake Rotoiti, we employed a bioenergetics model to assess the influence of stocking rates, timing of releases and prey abundance on growth and prey consumption. We hypothesised that stocking rates and prey abundance would affect growth and prey consumption by influencing per‐capita prey availability, and that the environmental conditions encountered by fish at the time of stocking would affect growth and consumption.
• 2 Prey consumption of stocked rainbow trout was calculated with the Wisconsin bioenergetics model. We calculated growth trajectories of released trout based on data from stocked trout that were released in spring and autumn from 1993 to 2009 and then re‐captured by anglers. Diet, prey energy density, body mass lost during spawning and lake temperature were measured locally.
• 3 Stocking timing had no effect on return rates to anglers or length or weight of caught fish. Although trout released in autumn were smaller than those released in spring, autumn‐released trout grew at a faster rate and had similar lengths and weights to spring cohorts after 2 years of growth in the lake. Modelled consumption parameters were negatively correlated with trout population size, suggesting that stocking rates (347–809 fish ha^?1 year^?1) caused density‐dependent effects on growth. Although common smelt (Retropinna retropinna) accounted for 85% of total prey consumption, no significant relationship was found between prey consumption by individual trout and adult smelt abundance, possibly because trout are targeting smaller smelt that our abundance estimate did not account for.
• 4 Releasing trout in autumn appears to be advantageous for growth, possibly because (i) temperature is more suitable for growth in autumn–winter than in spring–summer and (ii) prey for small trout is abundant in autumn. Mild winter conditions appear to enhance overwinter survival and growth of rainbow trout in warm‐temperate lakes compared to higher latitudes. This implies that moderately productive warm‐temperate lake ecosystems are highly suitable for trout growth in winter, but less so in summer, when lake stratification and high nutrient levels may create conditions suitable for algal blooms and hypolimnetic deoxygenation. High growth rates of trout in warm‐temperate lakes can therefore be supported by timing releases to coincide with favourable winter conditions.

     

Effects of pheromone plume structure and visual stimuli on the pheromone-modulated upwind flight of male gypsy moths (Lymantria dispar) in a Forest (Lepidoptera: Lymantriidae)

The pheromone-modulated upwind flight ofLymantria dispar males responding to different pheromone plume structures and visual stimuli designed to mimic trees was video recorded in a forest. Males flying upwind along pheromone plumes of similar structure generated tracks that were similar in appearance and quantitatively similar in almost all parameters measured, regardless of the experimentally manipulated visual stimuli associated with the pheromone source. Net velocities, ground speeds, and airspeeds of males flying in point-source plumes were slower than those of males flying in the wider, more diffuse plumes issuing from a cylindrical baffle. The mean track angle of males flying in plumes issuing from a point source was greater (oriented more across the wind) than that of males flying in plumes issuing from a transparent cylindrical baffle. Males flying in point-source plumes also turned more frequently and had narrower tracks overall than males responding to plumes from a cylindrical baffle. These data suggest thatL. dispar males orienting to pheromone sources (i.e., calling females) associated with visible vertical cylinders (i.e., trees) use predominantly olfactory cues to locate the source and that the structure of the pheromone plume markedly affects the flight orientation and the resultant track.     

Algal respiration and the regulation of phytoplankton biomass in a polymictic tropical lake (Lake Xolotlán,Nicaragua)

Community respiration in tropical Lake Xolotlán, Nicaragua, was assessed seasonally and during diurnal cycles, via oxygen consumption in bottle enclosures. Results were analysed in relation to phytoplankton biomass, mixing depth, depth of photic zone and phytoplankton production. A great part of community respiration was associated with the heterotrophic activity of the phytoplankton biomass or its degradation by bacteria and 80% of the variability in oxygen consumption was explained by the variation of chlorophyll-a. Specific rate of respiration was 1.5 mg O2 mg Chla-1 h-1 during diurnal cycles, which corresponded to less than 5% of the specific rate at optimum depth of production. Still, diurnal water column respiratory losses were always of the same magnitude as the total photosynthetic gains in the photic zone, since the mixing depth exceeded the depth of the photic zone. Total column net growth was zero at a ratio between depth of photic zone and mixing depth of 0.19. Water level variations however altered the mixing depth and affected this ratio and net growth. As a consequence, the phytoplankton biomass either increased or decreased until the ratio was re-established through changes of the photic zone depth, which was governed by the phytoplankton biomass itself through the chlorophyll-a light attenuation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effects of water hardness and alkalinity on the toxicity of uranium to a tropical freshwater hydra (Hydra viridissima)

In tropical Australian freshwaters, uranium (U) is of potential ecotoxicological concern, largely as a consequence of mining activities. Although the toxicity of uranium to Australian freshwater biota is comprehensive, by world standards, few data are available on the effects of physicochemical variables, such as hardness, alkalinity, pH and organic matter, on uranium speciation and bioavailability. This study determined the individual effects of water hardness (6.6, 165 and 330 mg l^-1 as CaCO₃) and alkalinity (4.0 and 102 mg l^-1 as CaCO₃), at a constant pH (6.0), on the toxicity (96 h population growth) of uranium to Hydra viridissima (green hydra). A 50-fold increase in hardness (Ca and Mg concentration) resulted in a 92% (two-fold) decrease in the toxicity of uranium to H. viridissima [i.e . an increase in the EC₅₀ value and 95% confidence interval from 114 (107-121) to 219 (192-246) µg l^-1]. Conversely, at a constant hardness (165 mg l-1 as CaCO₃), the toxicity of uranium to H. viridissima was not significantly (P > 0.05) affected by a 25-fold increase in alkalinity (carbonate concentration) [i.e. EC₅₀ values of 177 (166-188) and 171 (150-192) µg l^-1 at 4.0 and 102 mg l^-1 as CaCO₃, respectively]. A knowledge of the relationship between water chemistry variables, including hardness and alkalinity, and uranium toxicity is useful for predicting the potential ecological detriment in aquatic systems, and can be used to relax national water quality guidelines on a site-specific basis.     

Effects of water hardness and alkalinity on the toxicity of uranium to a tropical freshwater hydra (Hydra viridissima)

In tropical Australian freshwaters, uranium (U) is of potential ecotoxicological concern, largely as a consequence of mining activities. Although the toxicity of uranium to Australian freshwater biota is comprehensive, by world standards, few data are available on the effects of physicochemical variables, such as hardness, alkalinity, pH and organic matter, on uranium speciation and bioavailability. This study determined the individual effects of water hardness (6.6, 165 and 330 mg l^-1 as CaCO₃) and alkalinity (4.0 and 102 mg l^-1 as CaCO₃), at a constant pH (6.0), on the toxicity (96 h population growth) of uranium to Hydra viridissima (green hydra). A 50-fold increase in hardness (Ca and Mg concentration) resulted in a 92% (two-fold) decrease in the toxicity of uranium to H. viridissima [i.e. an increase in the EC₅₀ value and 95% confidence interval from 114 (107-121) to 219 (192-246) µg l^-1]. Conversely, at a constant hardness (165 mg l-1 as CaCO₃), the toxicity of uranium to H. viridissima was not significantly (P &gt; 0.05) affected by a 25-fold increase in alkalinity (carbonate concentration) [i.e. EC₅₀ values of 177 (166-188) and 171 (150-192) µg l^-1 at 4.0 and 102 mg l^-1 as CaCO₃, respectively]. A knowledge of the relationship between water chemistry variables, including hardness and alkalinity, and uranium toxicity is useful for predicting the potential ecological detriment in aquatic systems, and can be used to relax national water quality guidelines on a site-specific basis.     

Effects of postemergence experience on searching and landing responses of the insect parasitoid,Cotesia congregata (Say) (Hymenoptera: Braconidae), to plants

Postemergence experience with one of six plant species, in the presence of the host larva, modified the searching response of reproductively mature females of Cotesia congregata(Say) to these plants in at least one of three ways: (1) an increased response to the plant experienced at emergence, (2) an increased response to other plants, or (3) an inhibited response to other plants. Landing and searching responses were differentially affected by postemergence experience. For example, postemergence experience with tobacco (a common plant) in the presence of the host larva induced a landing preference for this plant over parsley (a novel plant) but did not affect searching responses to either plant, whereas experience with parsley and the host larva induced an increased searching response to parsley but a landing preference for tobacco. Differential effects of postemergence experience may reflect the type of stimuli involved in searching or landing and may have adaptive significance.