It this chemical or biology approach. And why? Explain clearly with your own wor

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It this chemical or biology approach. And why? Explain clearly with your own words

here, you only need to read the method sections to answer

http://www.pnas.org/content/98/5/2491.full

(all of a nepatne consisted and one of two 0.67.0.33, or 0.17 ml of stock four times) The chemical treatments control addition) control (water addition) vent control tubs received 133 of controls received 1.33 ml of water, and two levels of carbaryl addition. We made a stock solution by dissolving 501 mg of purity Rhone-Poulenc Research Triangle Park, NC into 250 ml of acetone. The carbaryl concentration of the stock solution was he stock solution was 27 (based on 8 mg/ml, based on Chemical Laboratory). Tubs yses by the Mississippi State Chemical Laboratory. Tubs Mississippi State 200, 1.00, 0 0.25 or to the low and high carbaryl treatments received either carbaryl treatments received concentrations 0.54.02a 0.50 of stock solution for nominal carbaryl concen- stock solution for nom inal carbaryl of 0.045 and 0.000 mg/liter ly These compare ceived 2 ml of acetone, whereas negative controls received 2 la 4 d test (15), Solvent control tubs received o.5 ml of of acetone, whereas negative controls recei ved 05 ml of water. During the 16 d experiments, and predator were asin the tub day and Predator realments consisted of either a caged larva plastic maculanum) or cups covered reapplied after water the chemical treatme nts were 10 times per day by slowly ity of the tadpoles h fiberglass window screening). Caged observed the activi predators emit chemical mber of tadpoles alive tub the that induce approaching each hout allowing the predators to kill the target and the proportion of live tadpoles that using Scan sampling end of the animals (29-3 periment, the surviving nted and weighed. cou Because tadpole growth was based only on those tadpoles that adpolcs first were fed ground fish food at a rate of 18% day (an abundant food mass per tadpole per d) are typically conducted in the absence of food, we added food because the tadpoles would not hav survived the longer iment witho ve ut food and beca survived, our estimates of growth could be upwardly biased if susceptible to the stresses of slower-growing tadpoles were more more foraging tadpoles reflect the Midway through experiments 2 and 3. we quantified the tadpoles had doubled in Once we visually estimated that the oxygen, temperature, pH total ammonia in each tub. was doubled. Caged predators were the food were using a Yellow small every Springs Instrument 55 dissolved o ygen meter (ooygen resolu- other day to produce the chemical cue(s) and, predators died 3 he predators were replaced. We ub water day and day 7 (chan 0.01 mg/liter; temperature resolution 0.1 C) Total nges grouped by atment), and ammonia and pH were measured using an Orion Expandable the chemi ionAnalyzer EA 940 (ammonia resolution 0.001 mg/liter, pH treatments were reapplied after water Each day, the of surviving tadpoles was counted. On requiring 0.01 pH) water changes, quantified before changing the water did not monitor water temperature, but was ained at 1 The activity, growth, and abiotic data were analyzed with standard ANOVA. The survivorship data did not meet the assumptions of standard ANOVA, so we conducted a nonpara- metric analysis on survivorship by first ranking the data and ther g an ANOVA on the ranks. Block interactions never were analyzed an analysis of variance formed as using final survival survival response variable d significance (P 05) and were dropped from th was not possible A repeated measures ANOVA several of the because control treatments had no variance on days sampled (100% 0% survival). Block effects analysis experiments, animal care was in acco dance with institutional guidelines. never approached significance (P 05) he analysis. and were dropped from Results Experiment 1. Survival remained high in the control chemi but the addition of carbaryl at all of the concen Experiments 2 and 3. In 2000, we conducted two, more-extensive tions caused high mortality within 1 week (Fig experiments to determine the effects of and predator remained high in the presence of carbary through day 5 and larval and experiments, we collected fertilized eggs from a different began a precipitous drop to a point that was significantly k (12 km south of first pop- than the controls (Fue P The chemical interacted with the n filtered tap in of 10 tadpoles 4,5, P When carbaryl was present at were randomly assigned to 10-liter polyethylene tubs filled with mg/liter, survival declined approximately 8% by tered tap water. Tubs were placed on shelves in four spatial regardless of predator treatment. When carbaryl was pres a laboratory under 15:9 h light dark ratio. The mg/liter, tadpole survival declined to 40% with pre adpoles in experiment 2 were mixture of 21 sibships (mean absent but declined to 3% with predators present. 1 SE 13 1 mg), whereas tadpoles in experiment 3 ere a mixture of 8 sibships (mean mass Experiments 2 and 3. In the more extensive experiments co In each experiment, tubs were randomly assi gned a factorial the following year, we found similar results (Figs. 2 a mbination of two predator treatments and six chemical trea eriment 2 (which contained the highest four carb ents (replicated four times), Predator treatments were ident centrations), survivorship was98% with either control to those in experiment 1, whereas the chemical treatments (regardless of predator treatment). However, in the p nsisted of a negative control (water addition), a solvent control carbaryl, surv ivorship dropped off precipitously bet etone addition), and four concentrations of carbaryl. In e highest concentration and day 6 After 16 d, mean survival across the fi eriment 2, we made a stock solution of carbaryl by dissolving concentration 4%, significantly lower than the c 18 mg of technical grade carbaryl into 100 ml of acetone. The treatments was 35.0, P 001). Predators di baryl concentration of the stock solution was 62.7 mg/ml ments (Fsse

Explanation / Answer

Method applied is a chemical approach because it studied the effect of toxicants on the predator, which fed the tadpole . Tadpole are like chemical dose ingested by carbaryl.

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