02553nas a2200241   4500008004100000020001400041245008500055210006900140260001200209300001400221490000700235520192100242653001502163653001302178653001102191653001102202653001502213100001902228700001402247700001302261700001302274856002402287       2008                        eng d  a0022-047700aTrade-offs between direct and indirect defences of lima bean (Phaseolus lunatus)0 aTradeoffs between direct and indirect defences of lima bean Phas  c2008///  a971 - 9800 v963 a1. Plant defence theory predicts trade-offs among defence traits as a result of resource limitation or pleiotropic effects. Although theoretically widely accepted, empirical demonstrations of such trade-offs are surprisingly scarce and mechanistic explanations are usually lacking. 2. We quantified cyanogenesis (the release of hydrogen cyanide (HCN)) as a direct defence and the emission of volatile organic compounds (VOCs) as an indirect defence against herbivores. To elucidate whether the trade-offs occur at the genetic or phenotypic level we investigated cultivated and wild-type accessions of lima bean (Fabaceae: Phaseolus lunatus L.) and compared different leaf developmental stages. Genetic relationships among the accessions were studied using amplified fragment length polymorphism (AFLP) analysis. 3. Cyanogenesis and the release of VOCs differed significantly among the accessions and were negatively correlated: high cyanogenic accessions released low amounts of VOCs and vice versa. The same remained true for the ontogenetic stages, since primary leaves of all accessions hardly ever produced HCN at all, yet regularly showed high release rates of VOCs. 4. Low and high cyanogenic accessions of lima bean formed distinct clades in an AFLP-based dendrogram, while wild-types and cultivars did not separate. The first pattern indicates that the underlying defensive syndromes are genetically conserved, while the latter is likely to be caused by a multiple origin of cultivated lima beans or an extensive gene flow among cultivated and wild plants. 5. Synthesis. Trade-offs between cynogenesis and VOC release were obvious both between accessions and at the ontogenetic level, and thus cannot be explained by pleiotropy. We contend that allocation restrictions and/or adaptations to different enemy pressures are most likely to explain why lima bean can invest into cyanogenesis or VOCs, but not both10aADAPTATION10amultiple10aPLANTS10atheory10aTRADE-OFFS1 aBallhorn, D.J.1 aKautz, S.1 aLion, U.1 aHeil, M.  uISI:00025837980001501624nas a2200193   4500008004100000020001400041245011100055210006900166260001200235300001400247490000700261520104300268653000901311653002201320653002201342100001601364700002601380856002401406       2008                        eng d  a1461-023X00aThe tropics: cradle, museum or casino? A dynamic null model for latitudinal gradients of species diversity0 atropics cradle museum or casino A dynamic null model for latitud  c2008///  a653 - 6630 v113 aSeveral ecological and evolutionary hypotheses have been proposed to explain the latitudinal diversity gradient (LDG), but a general model for this conspicuous pattern remains elusive. Mid-domain effect (MDE) models generate gradients of species diversity by randomly placing the geographic ranges of species in one- or two-dimensional spaces, thus excluding both evolutionary processes and the effect of contemporary climate. Traditional MDE models are statistical and static because they determine the size of ranges either randomly or based on empirical frequency distributions. Here we present a simple dynamic null model for the LDG that simulates stochastic processes of range shifts, extinction and speciation. The model predicts higher species diversity and higher extinction and speciation rates in the tropics, and a strong influence of range movements in shaping the LDG. These null expectations should be taken into consideration in studies aimed at understanding the many factors that generate latitudinal diversity gradients10aSIZE10aspecies diversity10aSPECIES-DIVERSITY1 aArita, H.T.1 aVazquez-Dominguez, E.  uISI:00025637690000100498nas a2200121   4500008004100000245015700041210006900198300001400267490000700281100002000288700002000308856004800328       2008                        eng d00aComments on the natural history and larval shelter construction of <i>Urbanus proteus</i> Linn. (Lepidoptera: Hesperiidae: Pyrginae) in southern Florida0 aComments on the natural history and larval shelter construction   a1008-10100 v621 aGreeney, H., F.1 aSheldon, K., S.  uhttps://caterpillars.myspecies.info/node/3300554nas a2200169   4500008004100000020001400041245013500055210006900190260001200259300001400271490000700285653001900292100001600311700001800327700001500345856002400360       2008                        eng d  a1442-998500aEffects of diversity loss on ecosystem function across trophic levels and ecosystems: A test in a detritus-based tropical food web0 aEffects of diversity loss on ecosystem function across trophic l  c2008///  a301 - 3060 v3310aTROPHIC LEVELS1 aBastian, M.1 aPearson, R.G.1 aBoyero, L.  uISI:00025492630000702585nas a2200229   4500008004100000020001400041245009500055210006900150260001200219300001600231490000700247520197100254653001302225653001702238653001402255653001302269653001402282653000902296653000902305100001702314856002402331       2008                        eng d  a0012-965800aMeasuring the impact of dynamic antipredator traits on predator-prey-resource interactions0 aMeasuring the impact of dynamic antipredator traits on predatorp  c2008///  a1640 - 16490 v893 aThis article analyzes the limitations of the most widely used method for quantifying the impact of dynamic antipredator traits on food chain dynamics and discusses alternative approaches. The standard method for a predator-prey-resource chain estimates the effects of the prey’s defensive behavior by comparing population densities or fitness measures in a ’’predator cue’’ treatment to those in a no-predator treatment. This design has been interpreted as providing a measure of the ’’nonconsumptive effect’’ of the predator on the prey and the ’’trait-mediated indirect effect’’ of the predator on the resource. Other approaches involve measurements of the impact of the behavior in the presence of functional predators. The questions addressed here are: (1) How consistent are the results of different approaches? (2) How time-dependent are their results? (3) How well do they correspond to theoretical measures of effect size? (4) How useful are the measurements in understanding system dynamics? A model of a tritrophic system in which the prey species adjusts a defensive trait adaptively is used to evaluate the experimental designs. Measures of changes in prey fitness or population density in a cue treatment generally include offsetting effects of the cost of the behavior and the benefit of more resources. This means that the sign of the effect, as well as its magnitude, may change depending on when the experiment is terminated. Because predation is not present in the cue treatment, few conclusions can be drawn about the impact of the behavior on population densities or fitness of the prey in a natural setting with predators. Cue experiments often do not accurately separate trait-mediated from density-mediated effects on the resource. Most scalar measures of effects are sensitive to experimental duration and initial densities. Use of a wider range of experimental designs to measure trait-related effects is called for10aDYNAMICS10ainteractions10apredation10aPREDATOR10apredators10aPREY10aSIZE1 aAbrams, P.A.  uISI:00025654030001702293nas a2200241   4500008004100000020001400041245008200055210006900137260001200206300001400218490000700232520167300239653001701912653001301929653001401942653001301956653001401969653000901983653000901992653000902001100001702010856002402027       2008                        eng d  a1522-061300aMeasuring the population-level consequences of predator-induced prey movement0 aMeasuring the populationlevel consequences of predatorinduced pr  c2008///  a333 - 3500 v103 aQuestions: (1) What impact does adaptive movement away from areas of high predation risk have on the dynamics of a prey species and its resource? (2) What can experiments that introduce or remove predator cues tell us about the answer to question (1)? Mathematical methods: These questions are addressed using a two-patch meta-community model in which predators and/or their cues are incorporated into a system consisting of a prey species and its resource. Predators and/or cues may be introduced to one or both patches. Key assumptions: Prey species move adaptively to maximize their instantaneous rate of increase, but also make some random movement. Predators move randomly or do not move. Resources seldom or never move between patches. Consumer species have saturating functional responses. Conclusions: (1) Adaptive movement can stabilize or destabilize the dynamics of the tri-trophic system. (2) Monitoring densities in a single patch may give a misleading indication of the global change in densities. (3) Adaptive prey movement in response to predator cues may increase or decrease prey density. (4) Predator introduction may cause an increase or decrease in the size of the prey population. (5) Short-term experiments with local measurements may greatly overestimate the impact of predators on prey and the behavioural component of that impact. (6) The dynamics and interspecific effects in a system with predators and adaptive avoidance by prey cannot in general be deduced from separate experiments with cues alone and with predators in the absence of the cues. (7) Conclusions from recent empirical studies should be reassessed in light of these results10aCONSEQUENCES10aDYNAMICS10apredation10aPREDATOR10apredators10aPREY10aRISK10aSIZE1 aAbrams, P.A.  uISI:00025601500000201812nas a2200289   4500008004100000020001400041245005400055210005200109260001200161300001400173490000700187520112100194653001701315653001201332653002101344653001601365653001401381653001301395653001401408653000901422653000901431653000801440653001901448100001401467700001701481856002401498       2008                        eng d  a0960-311500aReappraisal of the role of big, fierce predators!0 aReappraisal of the role of big fierce predators  c2008///  a685 - 6900 v173 aThe suggestion in the early 20th century that top predators were a necessary component of ecosystems because they hold herbivore populations in check and promote biodiversity was at first accepted and then largely rejected. With the advent of Evolutionary Ecology and a more full appreciation of direct and indirect effects of top predators, this role of top predators is again gaining acceptance. The previous views were predicated upon lethal effects of predators but largely overlooked their non-lethal effects. We suggest that conceptual advances coupled with an increased use of experiments have convincingly demonstrated that prey experience costs that transcend the obvious cost of death. Prey species use adaptive behaviours to avoid predators, and these behaviours are not cost-free. With predation risk, prey species greatly restrict their use of available habitats and consumption of available food resources. Effects of top predators consequently cascade down to the trophic levels below them. Top predators, the biggies, are thus both the targets of and the means for conservation at the landscape scale10abiodiversity10aecology10aindirect effects10aPOPULATIONS10apredation10aPREDATOR10apredators10aPREY10aRISK10aTOP10aTROPHIC LEVELS1 aAle, S.B.1 aWhelan, C.J.  uISI:000254360200001