Foraging behavior of the scale-eater Plecodus straeleni (Cichlidae,Teleostei) in Lake Tanganyika,Africa

Synopsis Sixty-nine individuals of Plecodus straeleni were followed for 1 h each in the field with the aid of SCUBA, and time budgets, hunting techniques and prey selection were investigated in relation to sex and body size. The time of cruising in midwater and on the substrate amounted to 3/4 of the total time. The rest of the time was mainly spent on five hunting techniques named pursuing, waiting, mingling, aiming and stealthy approaching. Pursuing (following a flying prey at high speed) was frequently used by adults, especially males, mainly to attack the spiny eel Afromastacembelus moorii. Waiting (keeping motionless on the substrate, waiting for a known prey) was used by some adult females when they tried to steal eggs of the mouthbrooder Cyathopharynx furcifer on the bower and by adult males when they targeted an eel having hidden under a rock. Mingling (mixing in a school of prey to attack school members) was a favorite tactic of subadults to attack plankton-feeders. Aiming (directing the head to a target fish for a moment) commonly occurred when both adults and subadults attacked solitary fishes. In stealthy approaching, the scale-eater approached an unwary prey from behind or sideway. Attacks by these hunting techniques amounted to 97% of the total attacks, which were made on 38 cichlid species and 7 non-cichlid species. Hunting techniques and prey preference varied not only with sex and size but even among consexuals of similar sizes. A number of individuals successively attacked only one or a few prey species in 1 h. Food specialization among individuals was attributed to their learning of the behavior and life style of preferred prey species.     

The effects of patch richness on con-specific interference in the parasitoid Ibalia leucospoides (Hymenoptera: Ibaliidae)

Abstract We experimentally studied con-specific interference in Ibalia leucospoides, a parasitoid of the woodwasp Sirex noctilio, on pine logs containing variable numbers of woodwasp larvae. Competiton occurred when two different-sized female parasitoids foraged on a host patch, and consequently the small female always abandoned the patch. Regardless of host density, con-specific presence did not affect the attack rate, the number of hosts attacked, nor patch residence time by the winner, when compared to a control female that foraged alone. In contrast, con-specific presence reduced patch time and the number of hosts attacked by the loser. Finally patch time (by both) as well as number of hosts attacked (by the winner only) increased with host density per patch. Our results suggest that con-specific presence has different consequences for different-sized females during patch exploitation.     

Utilization of purple and red sea urchins (Strongylocentrotus purpuratus Stimpson and S. franciscanus Agassiz) as food by the white sea urchin (Lytechinus anamesus Clark) in the field and laboratory

White sea urchins (Lytechinus anamesus Clark) attacked purple (Strongylocentrotus purpuratus Stimpson) and red (S. franciscanus Agassiz) sea urchins at Anacapa Island, California. Densities of white urchins were highest in the deep algal crust-dominated community where up to 6% of purple and 25% of red urchins were being attacked by white urchins. Up to 9% of Lytechinus anamesus in an area were actively eating stronglylocentrotids and usually, more than one white urchin was involved in the attack. In areas with low densities of white urchins, no strongylocentrotids were being attacked.After 36 h in the laboratory, there was no difference in the number of white urchins attacking injured or healthy purple urchins in each of the three experimental densities of white urchins. However, both injured and healthy urchins were attacked by more white urchins in high density. When given a choice between injured purple urchins or fresh kelp, white urchins overwhelmingly chose kelp. Data suggest that white urchins utilize other urchin species as an alternative source of food when more preferred food is absent, but will switch to preferred food should it become available.     

Colour-blindness and diversity: race frames and their consequences for white undergraduates at elite US universities

In this paper we bring together the literatures on frame analysis, the meaning of race and campus racial climate to analyse the race frames – lenses through which individuals understand the role of race in society – held by white students attending elite US universities. For most, the elite university experience coincides with a strengthening or emergence of the diversity frame, which emphasizes the positive benefits of cultural diversity. Still, many also hold a colour-blind frame, which sees race groups as equivalent and racial identities as insignificant. We highlight the ambivalence that these divergent frames create for student perspectives on affirmative action and interracial contact on campus. Our findings demonstrate the mutability of race frames. We also highlight the impact that institutions may have on individuals' race frames. The paper is based on in-depth interviews with forty-seven US-born white undergraduates attending Brown University and Harvard University.     

1918: Three perspectives on race and human variation

Race was an important topic to the physical anthropologists of 1918, but their views were not monolithic. Multiple perspectives on race are expressed in the first volume of the AJPA, which encompass biological determinism and assumptions about evolutionary processes underlying the race concept. Most importantly, many of the significant alternative approaches to the study of human variation were already expressed in 1918. This paper examines race from the different perspectives of three key contributions to the first volume of the AJPA: papers from Hrdlička, Hooton, and Boas. The meaning of race derived from this work is then discussed. Despite new understandings gained through the neo-Darwinian synthesis and the growth of genetics, the fundamentals of the modern discussions of race were already planted in 1918. Am J Phys Anthropol 2009. © 2009 Wiley-Liss, Inc.     

Great Spotted Cuckoos Frequently Lay Their Eggs While Their Magpie Host is Incubating

Species that suffer from brood parasitism face a considerable reduction in their fitness which selects for the evolution of host defences. To prevent parasitism, hosts can mob or attack brood parasites when they approach the host nest and block the access to the nest by sitting on the clutch. In turn, as a counter‐adaptation, brood parasites evolved secretive behaviours near their host nests. Here, we have studied great spotted cuckoo (Clamator glandarius) egg‐laying behaviour and defence by their magpie (Pica pica) hosts inside the nest using continuous video recordings. We have found several surprising results that contradict some general assumptions. The most important is that most (71%) of the parasitic events by cuckoo females are completed while the magpie females are incubating. By staying in the nest, magpies force cuckoo females to lay their egg facing the high risk of being attacked by the incubating magpie (attack occurred in all but one of the events, n = 15). During these attacks, magpies pecked the cuckoo violently, but could never effectively avoid parasitism. These novel observations expand the sequence of adaptations and counter‐adaptations in the arms race between brood parasites and their hosts during the pre‐laying and laying periods.     

Response ofNabis roseipennis [Heteroptera: Nabidae] to Larvae of Mexican bean beetle,Epilachna varivestis [Col.: Coccinellidae]

Laboratory studies were done to measure predation by adult damsel bugs,Nabis roseipennis Reuter [Heteroptera: Nabidae], on 3^rd instar larvae of Mexican bean beetle (MBB),Epilachna varivestis Mulsant [Coleoptera: Coccinellidae], and to measure longevity and body weight of the nabids. In the 1^st experiment, field-collected nabids were isolated for 24h in 9 cm Petri dishes with lima bean foliage (Phaseolus lunatus L.) and were assigned to one of 3 prey treatments: either 4 3^rd-instar MBB larvae, 4 3^rd-instar larvae of boll weevil (BW),Anthonomus grandis Boheman [Coleoptera: Curculionidae], or 2 larvae of each species. No MBB larvae were attacked in either the MBB treatment or 2-species treatment. In contrast, BW larvae were attacked in both BW and 2-species treatments. Significantly more BW larvae were attacked in the BW treatment than in the 2-species treatment, and both were greater than the number of MBB larvae attacked. Nabids that did not attack prey lost weight during the 24 h, whereas those that attacked prey gained weight. In the 2^nd experiment, nabids that had attacked prey were isolated with lima foliage, and nabids that had not attacked prey were kept with MBB and lima foliage until an attack or death. In no instances were MBB attacked. Longevity and the pattern of weight loss did not differ between nabids that did or did not attack prey. We discuss possible reasons for the failure ofN. roseipennis to attack MBB larvae, as well as the implications for using nabids to influence pest populations in the field.      

Testing a new hypothesis: plant vigor and phylloxera distribution on wild grape in Arizona

Summary Longer, meaning more vigorous, shoots of a wild grape clone (Vitis arizonica) were more susceptible to attack by second and third generations of leaf-galling grape phylloxera,Daktulopsphaira vitifoliae, as the growing season progressed. Although there was no significant difference in mean shoot length between attacked and unattacked shoots within a clone at the beginning of shoot elongation, attacked shoots were significantly longer than unattacked shoots when elongation had ceased (P<0.01). Also, long attacked shoots had a significantly greater population of phylloxera galls than short attacked shoots (P<0.01) as the season progressed. The phylloxera population on long shoots increased rapidly while the population on short shoots remained the same. Longer shoots also produced significantly more axillary shoots than shorter shoots as the season progressed (P<0.001), and the number of axillary shoots accounted for 66 percent of the variance in number of attacked leaves on a shoot. Experimental evidence showed that there was a significantly greater percentage of available leaves attacked on long shoots than on short shoots (P<0.05) and the leaves on long shoots generally had a greater number of galls per leaf. The relationship between shoot length and probability of attack was also tested by comparing shoots lengths of 10 attacked clones and 10 unattacked clones at a second location. Mean shoot lengths of attacked clones were significantly longer than mean shoot lengths of unattacked clones (P<0.05), and mean shoot lengths of attacked shoots within a clone were significantly longer than unattacked shoots (P<0.001). Longer shoot length accounted for 81 percent of the variance in probability of attack. The reason for this pattern of attack was that long shoots produced newly expanding leaves over a longer time during the growing season and multivoltine phylloxera require undifferentiated tissue to initiate gall formation. Patterns of attack within a shoot were characterized by an uneven distribution of galls among leaves. This was due to development time between generations and the current availability of undifferentiated tissue at times of colonization. This study supports the hypothesis that some herbivore species are favored more by vigorous plants than by stressed plants.     

The Body Mass Index-Mortality Relationship in White and African American Women

Objective : To examine the association of body mass index to all-cause and cardiovascular disease (CVD) mortality in white and African American women. Research methods and procedures : Women who were members of the American Cancer Society Prevention Study I were examined in 1959 to 1960 and then followed 12 years for vital status. Data for this analysis were from 8,142 black and 100,000 white women. Body mass index (BMI) was calculated from reported height and weight. Associations were examined using Cox proportional hazards modeling with some analyses stratified by smoking (current or never) and educational status (less than complete high school or high school graduate). Results : There was a significant interaction between ethnicity and BMI for both all-cause (p<0.05) and CVD mortality (p<<0.001). BMI (as a continuous variable) was associated with all-dause mortality in white women in all four groups defined by smoking and education. In black women with less than a high school education, there were no significant associations between BMI mortality. For high school-educated black women, there was a significant association between BMI and all-cause mortality. Among never smoking women with at least a high school education, models using the lowest BMI as the reference indicated a 40% higher risk of all-cause mortality at a BMI of 35.9 in black women vs. 27.3 in white women. Discussion : The impact of BMI on mortality was modified by educational level in black women; however, BMI was a less potent risk factor in black women than in white women in the same category of educational status.     

Antipredator Benefits of Schooling Behaviour in a Cyprinodontid Fish,the Banded Killifish (Fundulus diaphanus)

Fish schools are believed to provide antipredator benefits to their members. Two potential antipredator benefits, the dilution and confusion effects, of schooling were investigated in the laboratory using banded killifish (Fundulus diaphanus). Individual risk of being attacked and killed by a fish predator (white perch, Morone americana) declined with increasing killifish school size in a manner closely predicted by the dilution hypothesis. Perch were apparently not confused by schooling killifish since fish in groups of one did not suffer a disproportionately greater predation rate than fish in all larger school sizes. However, killifish straggling from the school were preferentially attacked and more successfully captured compared with school members. Schooling in the banded killifish therefore confers a considerable antipredator benefit to individual group members, at least through a dilution effect, and straying from a school has an associated increased risk of mortality to predation, which selects for schooling behaviour.     

Effect of sex and bright coloration on survival and predator‐induced wing damage in an aposematic lantern fly with startle display

1. Aposematic coloration in prey promotes its survival by conspicuously advertising unpalatability to predators. Although classical examples of aposematic signals involve constant presentation of a signal at a distance, some animals suddenly display warning colours only when they are attacked. 2. Characteristics of body parts suddenly displayed, such as conspicuous coloration or eyespot pattern, may increase the survival of the prey by startling the predator, and/or by signalling unpalatability to the predators at the moment of attack. 3. The adaptive value of such colour patterns suddenly displayed by unpalatable prey has not been studied. We experimentally blackened the red patch in the conspicuous red–white–black hindwing pattern displayed by an unpalatable insect Lycorma delicatula White (Hemiptera: Fulgoridae) in response to predator's attack. 4. There was no evidence that the presence of the red patch increased prey survival over several weeks. We hypothesise that predators generalised from the red–white–black patches on the hindwings of unpalatable L. delicatula to any similar wing display as a signal of unpalatability. Because a higher proportion of males than females stay put at their resting sites, displaying their wings in response to repeated attacks by predators, wing damage was more frequent in males than in females. 5. To our knowledge, this is the first experimental test of an adaptive role of aposematic signals presented by unpalatable prey during sudden displays triggered by direct predatory attack.     

Multivariate analysis of anthropometric data and classifications of British Columbian natives

Anthropometric data collected in native populations of British Columbia in the late 19th century by Franz Boas were analyzed by two multivariate techniques. Multivariate analysis of variance was used to test physical classificatory units devised by Boas and an ad hoc classification based on local cultural units. Both were found to have some empirical validity. Mahalanobis' D (Mahalanobis, '30) was computed between pairs of local groups, for both sexes. From these a matrix of differences was prepared and diagrams drawn to illustrate phenetic relationships among samples. By this means one cluster of groups, Interior B.C. peoples, could be distinguished and other local samples appeared distinctly different from each other. It was concluded that in the absence of genealogical data by which to identify local populations, local cultural units are preferable to more inclusive units for making empirical comparisons and classifications.     

Do territorial and non‐breeding Australian Magpies Gymnorhina tibicen influence the local movements of rural birds in New Zealand?

Australian Magpies Gymnorhina tibicen sometimes attack and kill other birds in New Zealand. Here we assess how Australian Magpies influence the local distribution of other birds in New Zealand and identify the members of an Australian Magpie population that display the most agonistic acts. We conducted regular observations on six territorial breeding groups and three non‐breeding flocks of Australian Magpies for 1 year to determine (1) if other birds avoid flying or foraging close to Australian Magpies, (2) the proportion of passing birds that are attacked and (3) which social subunits of the Australian Magpie population are most aggressive. In comparison with adjacent Magpie‐free control areas, significantly fewer birds of a range of species (e.g. Common Blackbird Turdus merula, Skylark Alauda arvensis, Yellowhammer Emberiza citrinella) foraged close (i.e. ≤ 50 m) to both territorial breeding groups and non‐breeding Australian Magpie flocks; fewer birds were also recorded flying near (i.e. ≤ 50 m) territorial breeding groups but not non‐breeding flocks. Excluding Australasian Harriers (Circus approximans: see below), only 8% of birds recorded within 50 m of territorial breeding groups were observed being attacked. Attacks were most frequent when numerous birds occurred near Australian Magpies and species recorded in the highest frequencies were generally attacked most. Territorial breeding groups attacked 39% of passing Australasian Harriers. All attacks consisted of the victim being swooped at or chased; no physical contact was ever observed. Both adult male and female breeding Australian Magpies were seen attacking other birds; juveniles in breeding groups sometimes supported adults but never initiated attacks. Australian Magpies in non‐breeding flocks were not seen attacking other birds, except Australasian Harriers (attacked in 17% of appearances). Our results suggest that some birds avoid foraging and/or flying close to Australian Magpies because they are sometimes chased by breeding adults of both sexes; however, the proportion of passing birds actually attacked was small. The numerous published observations of Australian Magpie attacks are apparently biased heavily towards sensational events that are rare. Possible reasons why Australian Magpies attack other birds are discussed.     

Physical activity correlates in adolescent girls who differ by weight status

Objective: This study compared correlates of physical activity (PA) among African‐American and white girls of different weight groups to guide future interventions. Research Methods and Procedures: Participants were 1015 girls (mean age, 14.6 years; 45% African‐American) from 12 high schools in South Carolina who served as control subjects for a school‐based intervention. Post‐intervention measures obtained at the end of ninth grade were used. PA was measured using the Three‐Day PA Recall, and a questionnaire measured social‐cognitive and environmental variables thought to mediate PA. Height and weight were measured, and BMI was calculated. Girls were stratified by race and categorized into three groups, based on BMI percentiles for girls from CDC growth charts: normal (BMI < 85th percentile), at risk (BMI, 85th to 94th percentile), and overweight (BMI ≥ 95th percentile). Girls were further divided into active and low‐active groups, based on a vigorous PA standard (average of one or more 30‐minute blocks per day per 3‐day period). Mixed‐model ANOVA was used to compare factors among groups, treating school as a random effect Results: None of the social‐cognitive or environmental variables differed by weight status for African‐American or white girls. Perceived behavioral control and sports team participation were significantly higher in girls who were more active, regardless of weight or race group. In general, social‐cognitive variables seem to be more related to activity in white girls, whereas environmental factors seem more related to activity in African‐American girls. Discussion: PA interventions should be tailored to the unique needs of girls based on PA levels and race, rather than on weight status alone.     

Sequential demethoxylation reactions during methylotrophic growth of methoxylated aromatic substrates with Eubacterium limosum

The exploitation of methoxylated aromatic monomers by Eubacterium limosum was restricted to the cleavage and consumption of the methoxyl substituents: the phenolic residues were not further attacked. Growth characteristics were similar to those previously described for this organism on methanol. Degradation of aromatics containing more than one methoxyl group occurred in a sequential manner and transient accumulation of intermediates (particularly methyl-gallate) took place, though the enzymic mechanism for this phenomenon remains obscure. Degradation of 3,4,5-trimethoxybenzoate necessitated the initial attack of the para-methoxyl group before those groups in meta positions could be metabolised.     

Behavioural response evoked by conspecific distress calls in two neotropical treefrogs

Anurans emit distress calls when attacked by predators as a defensive mechanism. As distress calls may trigger antipredator behaviour even in individuals that are not under attack, we tested whether this defensive behaviour induced behavioural changes in neighbouring conspecifics. We compared the behavioural responses of two species of Neotropical hylid frogs (genus Boana) to conspecific distress calls and white noise. Individuals of both species interrupted their vocal activity and decreased call rate after hearing the distress call. Natural variation on signal intensity calibrated among the nearest neighbours did not influence the response and we did not observe negative phonotaxis after any acoustic stimulus. Despite the fact that many predators are acoustically oriented, we could not determine if such response (reduced call rate) was induced by risk assessment or by the masking effect on advertisement calls. Boana faber responded similarly to white noise and distress calls, while B. bischoffi responded more intensely to distress calls. Duration of silence after playbacks in B. faber was longer than B. bischoffi. We suggest that, if the signals are interpreted as a risk cue by neighbouring conspecifics, each species may be preyed upon by different predators, as they may have led to distinct defensive strategies and different responses to distress calls. If risk assessment information is included in distress calls, it triggers behavioural responses only in the nearest neighbours, as we did not observe responses on the vocal activity of the interspecific chorus. Our results add relevant data about acoustic communication and interpretations by anurans, highlighting the importance of considering cues within common and widespread signals.     

Opportunistic Egg Feeding in the Kleptoparasitic Spider Argyrodes gibbosus

Argyrodes gibbosus is a kleptoparasitic spider in the web of spiders. It generally steals freshly captured prey from the web of its host. In Sicily, Argyrodes gibbosus parasitizes webs of the spider Cyrtophora citricola, a facultative colonial species. When a C. citricola female was present in its web, Argyrodes caught small prey in the web or tried to rob prey captured by the host; in that case, we never observed successful attacks on host egg-sacs. When the host disappeared from its web, the kleptoparasite modified its foraging strategies and attacked the host egg-sacs and ate the eggs. The exploitation of this new resource could ensure rapid development for the kleptoparasite which was characterized by the presence of larger females and a higher mating rate.     

Prey recognition time of praying mantids (Dictyoptera: Mantidae) and consequent survivorship of unpalatable prey (Hemiptera: Lygaeidae)

When juvenile praying mantids (Tenodera sinensis)were exposed to unpalatable prey (the milkweed bug Oncopeltus fasciatus),they attacked, sampled, and then usually rejected the prey. About 70% of the handling time was spent feeding. When offered a second milkweed bug, the mantids usually attacked the prey. However, the overall time required for the mantids to sample, recognize, and then reject the unpalatable prey decreased by half. The proportion of handling time that was spent feeding remained the same as in the first encounter. In contrast, when the second prey individuals encountered by mantids were Drosophila melanogaster,the flies were completely consumed and the proportion of handling time that was spent feeding significantly increased. When praying mantids were exposed to the milkweed bugs for the first time, up to 33% of the bugs survived attack by the mantids. Survival of milkweed bugs increased to 55% when mantids had been previously exposed to the bugs. In contrast, flies that were caught never survived.     

Attack by Hylobius warreni on grafted lodgepole pine and its relationships with monoterpene composition and scion : rootstock diameter ratio

1 A lodgepole pine seed orchard at the Prince George Tree Improvement Station (PGTIS), with up to 60% of grafted trees attacked by the Warren root collar weevil Hylobius warreni was investigated to determine whether relative monoterpene composition or scion : rootstock interactions of grafts affected susceptibility to attack. 2 There was a significant relationship between relative levels of α‐pinene, β‐thujene, β‐pinene, δ‐3‐carene and limonene in scion and rootstock in unattacked trees, indicating a potential effect of the scion monoterpene composition on their composition in the rootstock. 3 Relative content of δ‐3‐carene and β‐phellandrene differed significantly in root stocks of attacked and unattacked trees but, for individual clones, a significant difference was only detected for β‐phellandrene in one clone. δ‐3‐Carene levels may have been too low in the examined trees to exert a strong effect. 4 Interestingly, attack status was significantly associated with two scion monoterpenes: α‐thujene and α‐terpinolene, both of which had higher levels in unattacked than in attacked trees. 5 Warren root collar weevils appear largely unaffected by monoterpene content, but further study is required to determine whether high levels of δ‐3‐carene imparts some level of resistance to attack, and to verify whether the observed effects of scion monoterpenes are real or artefacts of the analysis. 6 Hylobius warreni‐attacked trees had smaller scion : rootstock diameter ratio (i.e. a large rootstock diameter relative to the scion diameter) than unattacked trees. This effect was consistent among clones, and was not due to the absolute diameter of the rootstock or the scion. Trees with increased diameter‐growth at the root collar (e.g. some grafted trees) may have increased susceptibility to attack by H. warreni, or diameter‐growth at the root collar is affected by the attack.     

Are European White Butterflies Aposematic?

It has been suggested that the white coloration of Pieridae butterflies is a warning signal and therefore all white Pieridae could profit from a mimetic resemblance. We tested whether green-veined white (Pieris napi) and orange-tip (Anthocharis cardamines) butterflies benefit from white coloration. We compared their relative acceptability to wild, adult pied flycatchers (Ficedula hypoleuca) by offering live A. cardamines and P. napi together with two non-aposematic butterflies on the tray attached to birds' nesting boxes. Experienced predators equally attacked white and non-white butterflies, and the order of attack among the Pieridae was random. If anything, there was a slight indication that the female A. cardamines was the least favoured prey. Since birds did not avoid white coloration, we compared the palatability of these two species against known palatable and unpalatable butterflies by presenting them to great tits (Parus major). Pieris brassicae, which has been earlier described as unpalatable, was also included in the palatability test. However, there were no significant differences in the palatability of the butterflies to birds, and even P. brassicae was apparently palatable to the great tits. Our results do not unambiguously support the hypothesis that the white coloration of Pieridae would signal unpalatability. Nevertheless, in our last experiment, pied flycatchers often rejected or left untouched free flying P. napi and A. cardamines. This suggests that other features in a more natural situation, such as the agile flight pattern or odours might still make them unprofitable to birds. This revised version was published online in July 2006 with corrections to the Cover Date.