Botanica Marina 47 (2004): 202–208  2004 by Walter de Gruyter • Berlin • New York

Variation in chemical defenses against herbivory in southwestern Atlantic Stypopodium zonale (Phaeophyta)

Renato C. Pereira1,*, Ange´lica R. Soares1,2, ¸ 1 and Vale´ria L. Teixeira1, Roberto Villaca 1 Bernardo A.P. da Gama Departamento de Biologia Marinha, Instituto de Biologia, Universidade Federal Fluminense (UFF), P.O. Box 100.644, CEP 24001-970, Nitero´i, Rio de Janeiro, Brazil, e-mail: [email protected] 2 Po´s-Graduac¸a˜o em Quı´mica Orgaˆnica, Instituto de Quı´mica, UFF, 24020-150, Nitero´i, Rio de Janeiro, Brazil 1

*Corresponding author

Abstract Many seaweeds produce secondary metabolites that deter herbivory, but intraspecific variation in both the identity and the concentration of chemical defenses has been documented rarely. In order to evaluate the occurrence of chemical variation in the brown seaweed Stypopodium zonale along the Brazilian coast, we investigated the defensive properties of crude extracts and major secondary metabolites found in specimens from two distant locations (Forno inlet, Bu´zios, southeastern Brazil and Fernando de Noronha archipelago, northeastern Brazil) against herbivory by the crab Pachygrapsus transversus and the sea urchin Lytechinus variegatus. At natural concentrations, the extracts from S. zonale from Bu´zios and Fernando de Noronha significantly deterred feeding by P. transversus and L. variegatus, although the former was more effective as a defense than the latter. Corroborating these results, the major metabolites atomaric acid, found in individuals from Bu´zios, and stypoldione, from Fernando de Noronha specimens, also inhibited herbivory, but atomaric acid was more effective as a defense against L. variegatus and P. transversus than stypoldione. The variation between S. zonale from two distant and different geographic locations in Brazil suggests that defensivechemicals from this seaweed are not qualitatively or quantitatively absolute or invariant characteristics of the species, and may represent an ecological specialization to successfully prevent herbivory. Keywords: chemical defense variation; herbivory; secondary metabolites; Stypopodium zonale.

Introduction Many seaweeds can deter a variety of common marine herbivores using a diverse array of secondary metabolites (Paul et al. 2001) which are qualitatively or quantitatively variable. In general, the intraspecific patterns of qualitative or quantitative variation in chemical defenses are largely undocumented (but see Van Alstyne et al.

1999), and thus underappreciated in marine organisms (Hay 1996). In addition, it is not known whether these variations are genetically or environmentally controlled or, in other words, if they are the result of long evolutionary or local ecological pressures. Due to the known broad ecological roles of seaweed secondary metabolites (Hay and Fenical 1988, Cronin 2001, Paul et al. 2001), these variations may be of significant importance and/or repercussion for population and community structure. In general, terpenoid compounds in seaweeds occur in relatively low concentrations, ranging from 0.2% to 2.0% of algal dry mass (DM) (Paul and Fenical 1986, Hay and Fenical 1988), although polyphenolic compounds in brown seaweeds can occur at concentrations as high as 15.0% of algal DM (Ragan and Glombitza 1986), although their concentrations can not be predicted by latitude alone (Targett et al. 1992), as previously thought. However, the variation in secondary metabolites may occur at a number of different levels: among individuals within a population (Paul and Van Alstyne 1988a,b, Puglisi and Paul 1997, Matlock et al. 1999) or among populations of the same species growing in different habitats (Paul and Fenical 1986, 1987, Paul et al. 1987, Paul and Van Alstyne 1988a). Populations of the green seaweed Halimeda from habitats with high herbivory pressure tend to contain higher levels of the potent defense agent halimedatrial than populations from areas with low herbivory (Paul and Van Alstyne 1988a). Similar variation has been observed in other green seaweeds such as Caulerpa, Penicillus, Udotea, and Rhipocephallus (Paul and Fenical 1986, 1987, Paul et al. 1987). Secondary metabolites can also vary according to the life history stage. However, because of the difficulty in distinguishing morphologically similar (e.g., isomorphic haploid and diploid) individuals, most studies have been limited to surveying only reproductive individuals (Thornber and Gaines 2003). Higher concentrations of polyphenolics occur in sporophylls of the kelp Alaria marginata Postels et Ruprecht than in vegetative tissues (Steinberg 1984, Van Alstyne et al. 1999). Similarly, polyphenol concentration in reproductive tissues of the rockweeds Fucus vesiculosus Linnaeus (Tuomi et al. 1989), F. gardneri Blanchette (Van Alstyne et al. 1999) and Pelvetia compressa J. Agardh (Van Alstyne et al. 1999) is higher than in vegetative portions. In many species of seaweed, higher levels of compounds are found in younger tissues than in older parts of the thallus (Phillips and Towers 1982, Hay et al. 1988a, Paul and Van Alstyne 1988b, Meyer and Paul 1995, de Nys et al. 1996). For example, in Halimeda spp. and Neomeris anulata Dickie, deterrent compounds are allocated to new growth regions (Hay et al. 1988a, Paul and Van Alstyne 1988b, Meyer and Paul 1995). On the other hand, higher levels of chemical defenses in older tissues have been found in the brown

R.C. Pereira et al.: Chemical defense variation in Stypopodium zonale

seaweed Dictyota ciliolata Sonders et Ku¨tzing (Cronin and Hay 1996). Besides the variation in concentration, different secondary metabolites may also be found in the same species of seaweed growing in different habitats (Hay and Fenical 1988, Pereira et al. 2000). For example, shallow and deep-water populations of the brown seaweed Stypopodium zonale (Lamouroux) Papenfuss produce different secondary metabolites (Gerwick et al. 1985), and the red alga Portieria hornemannii (Lyngbye) P. Silva varies in its composition of halogenated monoterpenes among different collection sites in the tropical Pacific Ocean (Gunatilaka et al. 1999). Accordingly, the brown seaweed Dictyota menstrualis (Hoyt) Schnetter, Ho¨rnig et Weber-Peukert differs in its major metabolite composition from the northwestern Atlantic (North Carolina; Hay 1996) to the southwestern Atlantic Ocean (Rio de Janeiro; Pereira et al. 2000). The brown seaweed S. zonale is chemically defended against herbivores through the action of stypotriol, a mixed biogenesis diterpenoid or meroditerpene (Hay et al. 1987, 1988b). This compound is lethal to the pomacentrid fish Eupomacentrus leucostictus Muller et Troschel (Gerwick and Fenical 1981). When naturally excreted in seawater, this compound oxidizes to the related compound stypoldione that exhibits several kinds of biological activities, such as toxicity to fish, prevention of cell division, immobilization of sperm, and inhibition of amino acids and nucleoside uptake (Gerwick and Fenical 1981, White and Jacobs 1983, O’Brien et al. 1984). Numerous collections of this seaweed from different geographic locations and years have yielded a wealth of different natural products (e.g., Gonza´lez et al. 1982, Gerwick et al. 1985, Wessels et al. 1999, Soares et al. 2003), suggesting the existence of a geographic variation in secondary metabolites that has not been thoroughly studied. In order to ascertain the nature of chemical defenses among Brazilian populations of S. zonale, the crude organic extracts and major secondary metabolites from two populations of this seaweed were investigated to specifically answer the following questions: 1) Is there variation in Stypopodium zonale secondary metabolite quantity and quality from north to south along the Brazilian littoral zone? 2) Do these metabolites play a defense role? 3) Does metabolite variation impact herbivore defense of S. zonale in different locales? 4) Are there geographic implications?

Materials and methods Organisms and study sites Stypopodium zonale is a common and luxuriant subtidal seaweed found along all Brazilian shores (Oliveira Filho 1977). Specimens of this phaeophyte were collected at ¸ ˜ o de Bu´zios (228459S, 418529W, Forno inlet, Armaca southeastern Brazil, Rio de Janeiro State) and at Resurreta channel, Fernando de Noronha archipelago (038519S, 328259W, northeastern Brazil, ca. 345 km off the coast of Rio Grande do Norte State), two very distant and distinct locations on the Brazilian coast (Figure 1). All S. zonale specimens were collected in shallow waters at depths ranging from 3 (Forno inlet) to 8 m (Fernando de

203

Figure 1 Collection sites of Stypopodium zonale on the Brazilian littoral.

Noronha). Although depth is a confound in this design, we have found that specimens of S. zonale collected at a broad range of depths, as well as in different seasons at Bu´zios exhibited an identical chemical composition (Pereira et al. unpublished results). Forno inlet is located at Bu´zios, a small resort town on the Brazilian southeastern coast. It is characterized by high wave energy, by the subtidal dominance of the seaweeds Dictyota cervicornis Ku¨tzing, Sargassum furcatum Ku¨tzing, S. zonale (Phaeophyta) and Plocamium brasiliense (Greville) Howe et Taylor (Rhodophyta), and by the co-occurrence of the endemic herbivorous gastropod Astraea latispina Philippi (0–2 m depth) (Yoneshigue 1985, Pereira et al. 2002). In the upper littoral zone, the coralline algae Amphiroa spp. and Jania adhaerens Lamouroux, and the green alga Codium spongiosum Harvey are characteristic, and the sea urchins Echinometra lucunter (Linnaeus) and Paracentrotus gaimardii (Blav.) Mortensen are the major inver¸ tebrate species (Yoneshigue 1985, Sabino and Villaca 1999, Pereira et al. 2002). The archipelago of Fernando de Noronha consists of one large island and 19 small, immediately adjacent islets, totaling ca. 26 km2 (Maida and Ferreira 1997). According to Eston et al. (1986), Resurreta channel has the highest algal diversity among the sites they studied. From 2 m to 9 m depth, the local benthic community is dominated by the brown seaweeds Dictyopteris spp., S. zonale, Sargassum spp. and Dictyota spp. Other common seaweeds include Caulerpa verticillata J. Agardh, Amphiroa spp., and Lobophora variegata Lamouroux. From 20 to 30 m depth, the zone of Montastrea cavernosa (Linnaeus) (Anthozoa) colonies (that grow as large pinnacles) can be found. A total of ninety-five species of fishes are known from the Fernando de Noronha region (Maida and Ferreira 1997), including endemic species such as Stegastes rocacensis (Emery) and Thalassoma noronhanum (Boulenger). Both herbivores assayed, the rock crab Pachygrapsus transversus (Gibbes) and the sea urchin Lytechinus variegatus (Lamarck), are very common organisms found all along the Brazilian coast and were collected at Boa Viagem island and Itaipu beach, respectively, in Nitero´i city, State

204 R.C. Pereira et al.: Chemical defense variation in Stypopodium zonale

of Rio de Janeiro. Both species are frequently dominant herbivores on Brazilian rocky coasts. Secondary metabolite isolation Specimens of Stypopodium zonale from Bu´zios (115.0 g DM) and Fernando de Noronha (105.0 g DM) were extracted in an identical fashion. Algal tissues were airdried, milled and extracted successively at room temperature with CH2Cl2. The solvent was then removed in vacuum to yield a dark green tar in both cases (19 g; 16.5% dry weight and 14 g; 13.3% of seaweed DM, respectively). Thin layer chromatography (TLC) revealed clearly distinct chemical profiles, which were further confirmed by 1 H NMR spectroscopy data. The crude extract of the algae from Bu´zios (0.86 g) was shaken with 1N NaOH, and subsequently with 1N HCl, in order to separate acidic and basic compounds. The acidic fraction was carefully separated by silica gel chromatography (Si 60 Merck, Rio de Janeiro, Brazil) and gradient eluted with nhexane to EtOAc, to yield 5 new fractions. The 3rd fraction was subjected to flash-chromatography over silica gel and eluted with n-hexane/EtOAc (8:2 v/v) to yield atomaric acid (1.65% of seaweed DM) as major metabolite. The identity of this compound was confirmed by comparison of spectroscopic and mass spectral data with those of Wessels et al. (1999). The crude extract of the algae from Fernando de Noronha (2.07 g) was separated by silica gel chromatography (Si 60 Merck) through a gradient elution from n-hexane to EtOAc to yield 12 fractions. On the basis of TLC and 1 H NMR data, fraction 10 (0.26 g) was submitted to flashchromatography over silica gel and eluted with n-hexane/ EtOAc (1:1 v/v) to yield stypoldione as the major metabolite (3.11% DM), identified by comparison with data from Mori and Koga (1992). Description of the experiments The anti-feeding properties of natural concentrations of the extracts and major metabolites from specimens of Stypopodium zonale from both sites were verified by the inclusion of natural concentrations of extracts or pure compounds in artificial foods prepared according to Hay et al. (1994). The artificial food (controls) was prepared by adding 0.72 g of agar to 20.0 ml of distilled water, heated in a microwave oven until boiling point. This mixture was then added to 16.0 ml of distilled water containing 2.0 g of freeze-dried Ulva sp. (Chlorophyta), a highly preferred food item. The experimental food (treatments) was similarly prepared, but the crude extract or pure compound was first dissolved in CH2Cl2, added to the 2.0 g of freeze-dried Ulva sp. and then the solvent was removed by rotary evaporation. This procedure is necessary to obtain a uniform coating of the metabolite on the algal particles prior to addition to agar (Hay et al. 1994). Importantly, whenever pure compounds were used in bioassays, the natural concentrations were maintained, i.e., 3.11% of seaweed DM for stypoldione and 1.65% DM for atomaric acid. Treatments and controls were hardened onto a mesh screen and cut into small pieces (10.0=10.0 squares

each ca. 1.0 mm on a side), which were then simultaneously offered to the crab Pachygrapsus transversus and the sea urchin Lytechinus variegatus in different experimental containers. Crab assays were carried out in small plastic aquaria, each containing 250 ml of filtered seawater (ns23 to 33 valid replicates; see Results section), and one specimen of P. transversus. The sea urchin assays were carried out in perforated plastic aquaria (1 l seawater) containing one individual of L. variegatus (ns16 to 30; see Results section), and placed in larger tanks containing ca. 500 l of flowing seawater. For all assays, the anti-feeding activities of crude extracts and pure compounds were estimated by comparing the number of squares consumed in both experimental foods (controls and treatments). New specimens of crab and sea urchin were used in each assay. Statistical analyses Since all experiments were performed independently of one another, the appropriate statistical procedure is to analyze the results from each experiment independently. Because paired-sample data did not exhibit a normal distribution, the significance of differences in consumption in all assays was evaluated with the Wilcoxon pairedsample test, a non-parametric equivalent to the paired-t test for dependent samples (Zar 1998). The consumption of controls and treatments was assumed to be dependent on each other, since consumption of one food item means less consumption of the other in the same container (Peterson and Renaud 1989). Differences were considered significant only when p-0.05 (as5%).

Results Natural concentrations of the crude extracts obtained from Bu´zios and Fernando de Noronha specimens of Stypopodium zonale significantly inhibited the herbivory by both the crab Pachygrapsus transversus and the sea urchin Lytechinus variegatus (p-0.05, Wilcoxon pairedsample test, Figure 2), confirming the predicted antifeeding properties of the compounds from this seaweed. When both extracts were simultaneously offered to herbivores, the crude extract from S. zonale from Bu´zios was more efficient as defense against both P. transversus and L. variegatus than the crude extract from populations of this alga from Fernando de Noronha (p-0.05, Wilcoxon paired-sample test, Figure 3). Two structurally distinct secondary metabolites were obtained as the major compounds from the populations of Stypopodium zonale from Bu´zios and Fernando de Noronha: atomaric acid (natural concentration: 1.65% DM) and stypoldione (3.11% DM), respectively (Figure 4). Both major secondary metabolites strongly inhibited herbivory by L. variegatus at natural concentrations (p-0.05, Wilcoxon paired-sample test, Figure 5). As expected from the results using crude extracts, stypoldione was less effective against both herbivores, and did not significantly inhibit feeding by P. transversus (p)0.05, Figure 5). Atomaric acid was effective as defense against both herbivores (p-0.05, Figure 5), confirming previous results obtained with crude extracts. Therefore, the chemical

R.C. Pereira et al.: Chemical defense variation in Stypopodium zonale

205

deterrent properties of the extracts from the two populations of S. zonale against P. transversus and L. variegatus can be attributed to their major secondary metabolites atomaric acid and stypoldione. The intensity of the effects of pure compounds on herbivores is in accordance with the results obtained with the crude extracts (Figure 3), i.e., the major compound atomaric acid, from Bu´zios plants, was more effective as a defense against both herbivores than stypoldione (p-0.05, Wilcoxon paired-sample test, Figure 6), found in Fernando de Noronha specimens.

Figure 2 The effect of crude extracts of Stypopodium zonale from Bu´zios and Fernando de Noronha on the feeding by Pachygrapsus transversus and Lytechinus variegatus relative to their respective controls. Vertical bars through each histogram show meansq1SD. Significance values are from the Wilcoxon paired-sample test. nsnumber of replicates.

Figure 5 The effect of natural concentrations of the major secondary metabolites, atomaric acid (1.65% of seaweed DM) and stypoldione (3.11% DM), on the feeding by Pachygrapsus transversus and Lytechinus variegatus, relative to their respective controls. Symbols and statistical tests are as in Figure 2.

Figure 3 Comparison of the effect of crude extracts from F. Noronha and Bu´zios populations of Stypopodium zonale on the feeding by Pachygrapsus transversus and Lytechinus variegatus when simultaneously offered to these herbivores. Symbols and statistical tests are as in Figure 2.

Figure 4 Structure of the major secondary metabolites stypoldione and atomaric acid found in F. Noronha and Bu´zios collections of Stypopodium zonale, respectively.

Figure 6 The comparative effect of stypoldione w3.11%x and atomaric acid w1.65%x natural concentrations on the feeding by Pachygrapsus transversus and Lytechinus variegatus when simultaneously offered to these herbivores. Symbols and statistical tests are as in Figure 2.

206 R.C. Pereira et al.: Chemical defense variation in Stypopodium zonale

Discussion Many brown seaweeds show extensive phenotypic variation, which can be generated by variation in a number of unknown biotic and abiotic extrinsic factors (Pavia and Brock 2000). Extrinsic changes in secondary metabolite production can have significant consequences for secondary production in nearshore marine communities, since they affect the palatability of dominating macroalgae. Variations in types and concentrations of seaweed secondary metabolites occur at a number of levels, including within and among individuals in a population, with the age of the individuals, and among populations growing in different habitats or geographic regions. In this study, we found that crude extracts from specimens of Stypopodium zonale from two distant locations on the Brazilian coast (Fernando de Noronha and Bu´zios) inhibited herbivory by the crab Pachygrapsus transversus and the sea urchin Lytechinus variegatus. In addition, the secondary metabolites stypoldione and atomaric acid were found as major compounds in Fernando de Noronha and Bu´zios specimens of S. zonale, respectively, and were responsible for the observed defense activity of the crude extracts against these herbivores. Thus, Brazilian specimens of S. zonale are chemically defended against herbivory, but by different chemicals, depending on location. However, since a strict bioassay guided fractionation was not performed, we can not fully discard the possibility that other deterrent compounds were also present in the crude extracts, although in smaller concentrations. Populations from habitats in which herbivory is intense tend to contain higher levels of more potent deterrent compounds than populations from areas of low herbivory. This may be especially true for tropical seaweeds exposed to a diverse assemblage of herbivores and commonly producing large amounts and diversities of compounds. In fact, populations of the green tropical seaweed Halimeda growing in habitats where herbivory is intense tend to contain higher levels of the potent deterrent halimedatrial than do populations from areas with low herbivory (Paul and Van Alstyne 1988a,b). Other tropical seaweeds of the Caulerpales, such as Penicillus, Udotea, Rhipocephalus, and Caulerpa often also produce higher concentrations or different types of compounds in populations from herbivore-rich habitats, compared to populations from herbivore-poor areas (Paul and Fenical 1986, 1987, Paul et al. 1987). In general, experimental evidence has demonstrated that tropical seaweeds are less palatable to herbivores due to a greater deterrence of their secondary metabolites (Bolser and Hay 1996, Cronin et al. 1997). The archipelago of Fernando de Noronha is on the northeastern Brazilian coast, in the tropics; in contrast, the Bu´zios region is subtropical. Thus, we could hypothesize that S. zonale from Fernando de Noronha should be more chemically defended than Bu´zios specimens. Comparing the activity of both extracts and major compounds, the difference between them becomes evident, but the extract and pure compound from the Bu´zios population of S. zonale were more effective as defense against herbivores. Consequently, the defensive difference between these Brazilian speci-

mens of S. zonale does not correspond to latitudinal variation in herbivore pressure, which seems to be in accordance with the recent findings in chemically defended marine organisms in Antarctic seas (Amsler et al. 2000), and in clear opposition to the prevailing hypothesis that tropical marine organisms are more chemically defended than high latitude biota. Additional chemical analyses of another pair of Stypopodium zonale populations from the Brazilian coast have revealed that populations from Rocas atoll reefs (038529S, 33849W) and Abrolhos archipelago (148469S, 398019W) are in agreement with the results of the present study, i.e., S. zonale from Rocas also produces stypoldione, while specimens from Abrolhos produce atomaric acid as the major metabolite (Soares et al. 2003). Hence, a pair of populations nearer to the equator is known to produce stypoldione (F. de Noronha and Rocas), while the two more southern populations synthesize atomaric acid (Abrolhos and Bu´zios), supporting the hypothesis of geographic variation in secondary metabolites. Despite the extensive recent literature on herbivory (see Hay 1996, Paul et al. 2001, and Paul 2004 for reviews), it still remains unclear whether variations in concentration and types of secondary metabolites result from herbivore-induced chemical defenses, local selection, genetic differences, or other factors not related to herbivores (Paul et al. 2001). Although chemical defenses are commonly associated with herbivore abundance and pressure, there have been no studies that conclusively demonstrate that herbivores impose selective pressures on the production of secondary metabolites (Van Alstyne and Paul 1990). The vast majority of studies associate actual or ecological conditions such as herbivore abundance or diversity with concentration or diversity of seaweed secondary metabolites, but the positive correlation obtained may be circumstantial only, not an evolutionary consequence. Shallow and deep water populations of the brown alga Stypopodium zonale from Belize contain different secondary metabolites (Gerwick et al. 1985). Hence, depth variations could be put forward to explain the results obtained here, since S. zonale specimens were collected at different depths at Bu´zios (3 m) and Fernando de Noronha (8 m). However, as noted above (Materials and methods) specimens of S. zonale collected at a broad range of depths, as well as in different seasons at Bu´zios exhibited an identical chemical composition (Pereira et al. unpublished results). Alternating life stages represent another possible source of variation in chemical defenses. Heteromorphic life stages of seaweeds are known to differ in their physiological and/or ecological properties. In this way, sporophytes and gametophytes may differ in growth rates, productivity, and resistance to herbivory (Lubchenco and Cubit 1980, Slocum 1980, Littler and Littler 1983, Clayton 1988, Zupan and West 1990). In addition, many species survive under disturbance or environments characterized by long periods of unfavorable conditions by exhibiting morphological variation through heteromorphic life histories (Hoffman and Santelices 1991). And, indeed, chemicals from different life history phases may vary (Masuda et al. 1997) and their extracts may have variable

R.C. Pereira et al.: Chemical defense variation in Stypopodium zonale

bioactivity (Moreau et al. 1984, Hornsey and Hide 1985, Robles-Centeno et al. 1996). The brown seaweed Stypopodium zonale exhibits a life cycle with alternating isomorphic gametophyte and sporophyte thalli. However, if these isomorphic sporophytes and gametophytes were to differ in their geographic distribution ranges (Dixon 1973), an investigation of ecological differentiation between the life history stages might be important. That is, the specimens of S. zonale studied could possess different chemicals according to alternating phases in the life cycle. However, to conclusively elucidate this issue, we would need to collect sterile and fertile, haploid (gametophyte) and diploid (sporophyte) specimens at the same collection site. Seasonal collections of S. zonale in Bu´zios yielded chemically identical sterile and fertile specimens, but only sporophytes were found, and all other collection sites are too remote to allow seasonal collections (Pereira et al. unpublished results). Independently of factors conditioning the observed qualitative difference in chemical defenses of this seaweed, our results reinforce the idea that seaweed secondary metabolites are not a qualitative or quantitatively absolute or invariant characteristic of a species. Hence, the chemical differentiation among populations of some seaweeds may represent an important ecological specialization for dealing with geographic differences in herbivory pressure.

Acknowledgements National Brazilian Research Council (CNPq) and CAPES supported this research. R.C.P. and V.L.T. thank CNPq for their Research Productivity Fellowships (Proc. 521914/96-5 and 303016/90-6, respectively), while B.A.P.G. and A.R.S. gratefully acknowledge CAPES for their post-doctoral (ProDoc) and PhD fellowships, respectively. J.H.S. Miyamoto greatly helped in lab assays. The authors are also indebted to the anonymous reviewers for their excellent comments that greatly improved the quality of this manuscript.

References Amsler, C.D., J.B. McClintock and B.J. Baker. 2000. Chemical defenses of Antarctic marine organisms: a reevaluation of the latitudinal hypothesis. In: (B. Davidson, C. Howard-Williams and P. Brody, eds) Antarctic ecosystems: models for wider ecological understanding. N.Z. Natural Sciences, Christchurch, New Zealand. pp. 158–164. Bolser, R. and M.E. Hay. 1996. Are tropical plants better defended? Palatability and defenses of temperate versus tropical seaweeds. Ecology 77: 2269–2286. Clayton, M.N. 1988. Evolution and life histories of brown algae. Bot. Mar. 31: 379–397. Cronin, G. 2001. Resource allocation in seaweeds and marine invertebrates: chemical defense patterns in relation to defense theories. In: (J.B. McClintock and B.J. Baker, eds) Marine chemical ecology. CRC Press, Baton Rouge. pp. 325–353. Cronin, G. and M.E. Hay. 1996. Within plant variation in seaweed palatability and chemical defenses: optimal defense theory versus the growth differentiation balance hypothesis. Oecologia 105: 361–368.

207

Cronin, G., V.J. Paul, M.E. Hay and W. Fenical. 1997. Are tropical herbivores more resistant than temperate herbivores to seaweed chemical defenses? Diterpenoid metabolites from Dictyota acutiloba as feeding deterrents for tropical versus temperate fishes and urchins. J. Chem. Ecol. 23: 289–302. de Nys R., P.D. Steinberg, C.N. Rogers, T.S. Charlton and M.W. Duncan. 1996. Quantitative variation of secondary metabolites in the sea hare Aplysia parvula and its host plant, Delisea pulchra. Mar. Ecol. Prog. Ser. 130: 135–146. Dixon, P.S. 1973. Biology of the Rhodophyta. Oliver & Boyd, Edinburgh, UK. pp. 285. Eston, V.R., A.E. Migotto, E.C. Oliveira Filho, S.A. Rodrigues and J.C. Freitas. 1986. Vertical distribution of benthic marine organisms on rocky coast of the Fernando de Noronha Archipelago (Brazil). Bolm. Inst. Oceanogr. S. Paulo 34: 37–53. Gerwick, W.H. and W. Fenical. 1981. Ichthyotoxic and cytotoxic metabolites of the tropical brown alga, Stypopodium zonale. J. Org. Chem. 46: 22–27. Gerwick, W.H., W. Fenical and J.N. Norris. 1985. Chemical variation in the tropical seaweed Stypopodium zonale (Dictyotaceae). Phytochemistry 24: 1279–1283. Gonza´lez, A.G., M.A. Alvarez, J.D. Martı´n, M. Norte, C. Pe´rez and J. Rovirosa. 1982. Diterpenoids of mixed biogenesis in Phaeophyta. Biogenetic-type interconversions. Tetrahedron 38: 719–728. Gunatilaka, A.A.L., V.J. Paul, P.U. Park, M.P. Puglisi, A.D. Gitler, D.S. Eggleston, R.C. Haltiwanger and D.G.I. Kingston. 1999. Apakaochtodenes A and B: two tetrahalogenated monoterpenes from the red marine alga Portieria hornemannii. J. Nat. Prod. 62: 1376–1378. Hay, M.E. 1996. Marine chemical ecology: what’s known and what’s next? J. Exp. Mar. Biol. Ecol. 200: 103–134. Hay, M.E. and W. Fenical. 1988. Marine plant-herbivore interactions: the ecology of chemical defense. Ann. Rev. Ecol. Syst. 19: 111–145. Hay, M.E., W. Fenical and K. Gustafson. 1987. Chemical defense against diverse coral reef herbivores. Ecology 68: 1581–1591. Hay, M.E., V.J. Paul, S.M. Lewis, K. Gustafson, J. Tucker and R.N. Trindell. 1988a. Can tropical seaweeds reduce herbivory by growing at night – diel patterns of growth, nitrogen-content, herbivory, and chemical versus morphological defenses. Oecologia 75: 233–245. Hay, M.E., J.E. Duffy and W. Fenical. 1988b. Seaweed chemical defenses: among-compound and among-herbivore variance. Proc. 6th Intl. Coral Reef Symp. 3: 43–48. Hay, M.E., Q.E. Kappel and W. Fenical. 1994. Synergisms in plant defenses against herbivores: interactions of chemistry, calcification, and plant quality. Ecology 75: 1714–1726. Hoffman, A.J. and B. Santelices. 1991. Banks of microscopic forms: hypotheses on their functioning and comparisons with seed banks. Mar. Ecol. Prog. Ser. 79: 185–194. Hornsey, I.S. and D. Hide. 1985. The production of antimicrobial compounds by British marine algae. IV. Variation of antimicrobial activity with algal generation. Br. Phycol. J. 20: 21–25. Littler, M.M. and D.S. Littler. 1983. Heteromorphic life-history strategies in the brown alga Scytosiphon lomentaria (Lyng.) Link. J. Phycol. 19: 425–431. Lubchenco, J. and J. Cubit. 1980. Heteromorphic life history of certain marine algae as an adaptation to variation in herbivory. Ecology 61: 676–687. Maida, M. and B.P. Ferreira. 1997. Coral reefs of Brazil: an overview. Proc. 8th Coral Reef Symp. 1: 263–274. Masuda, M., T. Abe, S. Sata, T. Suzuki and M. Suzuki. 1997. Diversity of halogenated secondary metabolites in the red alga Laurencia nipponica (Rhodomelaceae, Ceramiales). J. Phycol. 33: 196–208. Matlock, D.B., D.W. Ginsburg and V.J. Paul. 1999. Spatial variability in secondary metabolite production by the tropical red alga Portieria hornemannii. Hydrobiologia 399: 267–273.

208 R.C. Pereira et al.: Chemical defense variation in Stypopodium zonale

Meyer, K.D. and V.J. Paul. 1995. Variation in aragonite and secondary metabolite concentrations in the tropical green seaweed Neomeris annulata: effects on herbivory by fishes. Mar. Biol. 122: 537–545. Moreau, J.D., D. Pesando and B. Caram. 1984. Antifungal and antibacterial screening of Dictyotales from the French Mediterranean coast. Hydrobiologia 116/117: 521–524. Mori, K. and Y. Koga. 1992. Synthesis and absolute configuration of (-)stypoldione. Bioorg. Med. Chem. Lett. 2: 391–394. O’Brien, E.T., S. White, R.S. Jacobs, G.B. Boder and L. Wilson. 1984. Pharmacological properties of a marine natural product, stypoldione, obtained from the brown alga Stypopodium zonale. Hydrobiologia 116/117: 141–145. Oliveira Filho, E.C. 1977. Algas marinhas bentoˆnicas do Brasil. Tese de Livre-Doceˆncia. Inst. Biocieˆncias, Universidade de Sa˜o Paulo. pp. 407. Paul, V.J. 2004. Chemical mediation of interactions among marine organisms. Nat. Prod. Rep. 21: 189–209. Paul, V.J. and W. Fenical. 1986. Chemical defense in tropical green algae, order Caulerpales. Mar. Ecol. Prog. Ser. 34: 157–169. Paul, V.J. and W. Fenical. 1987. Natural products chemistry and chemical defense in tropical marine algae of the phylum Chlorophyta. In: (P.J. Scheuer, ed.) Bioorganic marine chemistry. Vol. I. Springer-Verlag, Berlin. pp. 1–37. Paul, V.J. and K.L. Van Alstyne. 1988a. Antiherbivore defenses in Halimeda. Proc. 6th Intl. Coral Reef Symp. 3: 133–138. Paul, V.J. and K.L. Van Alstyne. 1988b. Chemical defense and chemical variation in some tropical Pacific species of Halimeda (Chlorophyta, Halimedaceae). Coral Reefs 6: 263–270. Paul, V.J., M.M. Littler, D.S. Littler and W. Fenical. 1987. Evidence for chemical defense in the tropical green alga Caulerpa ashmeadii (Caulerpaceae: Chlorophyta): isolation of new bioactive sesquiterpenoids. J. Chem. Ecol. 13: 1171–1185. Paul, V.J., E. Cruz-Rivera and R.W. Thacker. 2001. Chemical mediation of macroalgal herbivore interactions: ecological and evolutionary perspectives. In: (J.B. McClintock and B.J. Baker, eds) Marine chemical ecology. CRC Press, Baton Rouge. pp. 227–265. Pavia, H. and E. Brock. 2000. Extrinsic factors influencing phlorotannin production in the brown alga Ascophyllum nodosum. Mar. Ecol. Prog. Ser. 193: 285–294. Pereira, R.C., D.N. Cavalcanti and V.L. Teixeira. 2000. Effects of secondary metabolites from the tropical Brazilian brown alga Dictyota menstrualis on the amphipod Parhyale hawaiensis. Mar. Ecol. Prog. Ser. 205: 95–100. Pereira, R.C., M.D. Pinheiro, V.L. Teixeira and B.A.P. da Gama. 2002. Feeding preferences of the endemic gastropod Astraea latispina in relation to chemical defenses of Brazilian tropical seaweeds. Braz. J. Biol. 62: 33–40. Peterson, C.H. and P.E. Renaud. 1989. Analysis of feeding preference experiments. Oecologia 80: 82–86. Phillips, D.W. and G.H.N. Towers. 1982. Chemical ecology of red algal bromophenols. I. Temporal, interpopulational and within-thallus measurements of lanosol levels in Rhodomela larix (Turner) C. Agardh. J. Exp. Mar. Biol. Ecol. 58: 287–293. Puglisi, M.P. and V.J. Paul. 1997. Intraspecific variation in sec-

ondary metabolite production in the red alga Portieria hornemannii: monoterpene concentrations are not influenced by nitrogen and phosphorus enrichment. Mar. Biol. 128: 161–170. Ragan, M.A. and K.W. Glombitza. 1986. Phlorotannins: brown algal polyphenols. Prog. Phycol. Res. 4: 129–241. Robles-Centeno, P.O., D.L. Ballantine and W.H. Gerwick. 1996. Dynamics of antibacterial activity in three species of Caribbean marine algae as a function of habitat and life history. Hydrobiologia 326/327: 457–462. ¸ 1999. Estudo comparativo de me´toSabino, C.M. and R. Villaca. dos de amostragem de comunidades de costa˜o. Rev. Bras. Biol. 59: 407–419. Slocum, C.J. 1980. Differential susceptibility to grazers in two phases of an intertidal alga: advantages of heteromorphic generations. J. Exp. Mar. Biol. Ecol. 46: 99–110. ¸ 2003. VarSoares, A.R., V.L. Teixeira, R.C. Pereira and R. Villaca. iation on diterpene production by the Brazilian alga Stypopodium zonale (Dictyotales, Phaeophyta). Biochem. Syst. Ecol. 31: 1347–1350. Steinberg, P.D. 1984. Algal chemical defenses against herbivores: allocation of phenolic compounds in the kelp Alaria marginata. Science 223: 405–407. Targett, N.M., L.D. Coen, A.A. Boettcher and C.E. Tanner. 1992. Biogeographic comparisons of marine algal polyphenolics: evidence against a latitudinal trend. Oecologia 89: 464–470. Thornber, C.S. and S.D. Gaines. 2003. Spatial and temporal variation of haploids and diploids in populations of four congeners of the marine alga Mazzaella. Mar. Ecol. Prog. Ser. 258: 65–77. Tuomi, J., H. Ilvessalo, P. Niemela, S. Siren and V. Jormalainen. 1989. Within-plant variation in phenolic content and toughness of the brown alga Fucus vesiculosus L. Bot. Mar. 32: 505–509. Van Alstyne, K.L. and V.J. Paul. 1990. The biogeography of polyphenolic compounds in marine macroalgae: temperate brown algal defenses deter feeding by tropical herbivorous fishes. Oecologia 84: 158–163. Van Alstyne, K.L., J. McCarthy, C.L. Hustead and D.O. Duggins. 1999. Geographic variation in polyphenolic levels of Northeastern Pacific kelps and rockweeds. Mar. Biol. 133: 371–379. Wessels, M., G.M. Ko¨nig and A.D. Wright. 1999. A new tyrosine kinase inhibitor from the marine brown alga Stypopodium zonale. J. Nat. Prod. 62: 927–930. White, S.J. and R.S. Jacobs. 1983. Effect of stypoldione on cell cycle progression, DNA and protein synthesis, and cell division in cultured sea urchin embryos. Mol. Pharmacol. 24: 500–508. Yoneshigue, Y. 1985. Taxonomie et ecologie des algues marines dans la re´gion de Cabo Frio (Rio de Janeiro, Bre´sil). The`se Doct. Sci. Fac. Sci. Luminy. Univ. Aix-Marseille II. pp. 466. Zar, J.H. 1998. Biostatistical analysis. 4th edition. Prentice-Hall, Englewood Cliffs, New Jersey, USA. pp. 929. Zupan, J.R. and J.A. West. 1990. Photosynthetic responses to light and temperature of the heteromorphic marine alga Mastocarpus papillatus. J. Phycol. 26: 232–239. Received 30 October, 2003; accepted 13 April, 2004

Variation in chemical defenses against herbivory in ...

logical specialization to successfully prevent herbivory. Keywords: chemical ... haploid and diploid) individuals, most studies have been limited to .... data from Mori and Koga (1992). Description of ..... N.Z. Natural Sciences, Christ- church, New ...

159KB Sizes 1 Downloads 188 Views

Recommend Documents

Variation in chemical defenses against herbivory in ...
ulations of the same species growing in different habitats ... observed in other green seaweeds such as Caulerpa, .... It is characterized by high wave energy,.

Press_ Small Business Defenses Against Bankruptcy Trustee ...
Press_ Small Business Defenses Against Bankruptcy Trustee “Preference Actions”.pdf. Press_ Small Business Defenses Against Bankruptcy Trustee ...

Variation in dung beetle (Coleoptera: Scarabaeoidea) - CiteSeerX
Dec 13, 2016 - in the Bulgarian Rhodopes Mountains: A comparison. JORGE M. LOBO1 ... mators ACE (abundance-based coverage estimator) and Chao1.

Mate guarding, competition and variation in size in ...
97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, U.K. (email: [email protected]). ..... Princeton, New Jersey: Princeton University Press. Arak, A. 1988.

Mate guarding, competition and variation in size in ...
depletion of energy stores during the mate-searching period, when males feed ..... Rubenstein (1987) proposed size-dependent alternative mating behaviour in ...

Reconciliation and variation in post-conflict stress in ...
Nov 1, 2001 - have two functions: (1) to repair relationship damaged by aggression such that .... (SDB), such as scratching, auto-grooming, and yawning, is associated with .... begun within 15 min (either side) of the start time of the PC. MCs ... Wh

Latitudinal variation in plantБherbivore interactions in ...
Present address: School of Environmental Sciences,. Univ. of East Anglia, ... limitations in design (reviewed by Pennings et al. 2001). One of the most ..... the distribution of species. Б Harper and Row. Menge, B. A. 2003. The overriding importance

Fine-grained variation in caregivers' /s - ENS
An alternative hypothesis postulates instead that infants start out with certain auditory- .... acoustic characteristic of /s/ is that the peak of energy during the ...

Latitudinal variation in herbivore pressure in ... - Semantic Scholar
Jan 1, 2009 - three methods to test the hypotheses that (1) herbivores are more abundant .... or measurement was replicated six to eight times per site, and averaged ... combined with other data in a previous study (Pennings and Silliman ...

Mate guarding, competition and variation in size in ...
97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, U.K. (email: ... viously successful males that can copulate again within. 2 h (Bridge 1999), ..... Newsletter of.

Adaptive variation in judgment and philosophical intuitionq
Feb 12, 2009 - article (e.g. in Word or Tex form) to their personal website or .... external (e.g., social and physical) environments regardless of logical ...

Collective frequency variation in network ...
Apr 25, 2016 - systems and show that for generic directed networks the collective frequency of the ensemble is not the same as the mean of the individuals' ...

Fine-grained variation in caregivers' /s - ENS
Based on online coding, habituation was determined at the end of a trial if the average looking time for that trial and the two preceding ones dropped below 40% ...

Reconciliation and variation in post-conflict stress in ... - baillement.com
Nov 1, 2001 - have two functions: (1) to repair relationship damaged by aggression such .... (SDB), such as scratching, auto-grooming, and yawning, is associated with ..... culated individuals' mean rates of each class of SDB (in bouts per.

Investigating Variation in Replicability.pdf
There was a problem previewing this document. Retrying... Download. Connect more apps... Try one of the apps below to open or edit this item. Investigating ...

pdf-15208\chemical-engineering-cambridge-series-in-chemical ...
... Modeling (1986); and Polymer Melt Processing: Page 3 of 9. pdf-15208\chemical-engineering-cambridge-series-in-chemical-engineering-by-morton-denn.pdf.

Brothers in Arms Against Cancer
Apr 7, 2011 - do you know of his elder brother, Erasmus? He was a physician, inventor, and philoso- pher of some repute. Familiar with Cassandra. Austen, the amateur painter and Jane's sister? Probably not. Famous brothers and sisters often overshado

STATIONARITY AGAINST INTEGRATION IN THE ...
+ αr tr. T )I{κ ̸= 0} + t. ∑ k=1 ρt−kηk + εt where the source of the stochastic .... Let the partial sum processes of (̂εt) and (̂ε 2 t ) be defined as. (1.9). St = t. ∑.

Topics in Chemical Engineering
... 2008 both PDF and HTML across all Latest trending topics being covered on ... by plants and other organisms to convert light energy into chemical energy that ...

Himmelblau-Basic-Principles-and-Calculations-in-Chemical ...
Page 2 of 857. Page 2 of 857. Page 3 of 857. Page 3 of 857. Himmelblau-Basic-Principles-and-Calculations-in-Chemical-Engineering-8th Edition.pdf.

Chemical-Engineering-An-Introduction-Cambridge-Series-In ...
Page 1 of 32. Download ~~~~~~!!eBook PDF Chemical Engineering: An Introduction (Cambridge Series In Chemical Engineering). (PDF) Chemical Engineering: An Introduction (Cambridge. Series In Chemical Engineering). CHEMICAL ENGINEERING: AN INTRODUCTION

Himmelblau-Basic-Principles-and-Calculations-in-Chemical ...
Himmelblau-Basic-Principles-and-Calculations-in-Chemical-Engineering-8th Edition.pdf. Himmelblau-Basic-Principles-and-Calculations-in-Chemical-Engineering-8th Edition.pdf. Open. Extract. Open with. Sign In. Details. Comments. General Info. Type. Dime

Green-Chemistry-In-Chemical-Syntheses.pdf
Page 1 of 2. Download ]]]]]>>>>>PDF Download Green Chemistry In Chemical Syntheses. (PDF) Green Chemistry In Chemical Syntheses. GREEN CHEMISTRY ...