寄生蟲是生態群聚中重要的一部分；但是直到最近，寄生蟲才較常被納入食物網的研究中。利用最近發表的文獻資料與相關的網絡分析工具，我的研究嘗試釐清寄生蟲在水生生態系的食物網網路中所扮演的角色。首先，本研究闡明寄生蟲在食物網中並非隨機分布的，而是與其宿主在食物網的位置有關。宿主在食物網的位置如果擁有較多的獵物種類、較靠近所有的獵物、或是能從食物網的底層往上累積較多的資源，其寄生蟲之種類多樣性便較高。相對的，若是宿主在食物網的位置有較多的掠食者、較靠近所有的掠食者、或是位在許多食物鏈路徑的必經之處，則此宿主的寄生蟲往上傳遞的比例越高。再者，本研究利用生態模式模擬食物網加入寄生蟲後，其網絡強固性之變化。首次將寄生蟲所造成之網絡強固性減少，分成網路的結構複雜性改變與寄生蟲特性兩個成因來探討；研究結果顯示造成食物網強固性減少的主因在於寄生蟲對宿主資源利用的可替代性較低。本研究建議利用寄生蟲對次級滅絕特別敏感的特性，可將寄生蟲當成食物網功能是否完整之領先指標。最後，本研究以過去食物網中物種的拓樸重要性指標為基礎，延伸加入食性營養關係中能量流動方向性的正負符號概念，發展出一套新的具正負符號的拓樸重要性指標。此一指標涵括食物網中的上行與下行效應、直接與間接作用，可用來定量物種間彼此的交互作用。應用此一新指標在包含寄生蟲的食物網資料上，可幫助我們進一步釐清寄生蟲在食物網中的角色與和其他功能群間的交互關係。

Parasites are ubiquitous in ecological communities but they haven’t been routinely included in food web studies until very recent. Using recently published data and the tool of network analysis, I elucidated features associated with the pattern of parasitism in food web networks. First, I showed that parasites are not only occurring in non-random fashion in food webs but also positively associated with the prominent network positions occupied by their hosts. Meanwhile, a host species with high parasite diversity tends to have a wide diet range, occupy a network position close to many prey species, or occupy a network position that can better accumulate resources from species at lower trophic levels, whereas a host species with higher vulnerability to predators, being at a network position close to many predatory species, or being involved in many different food chains, tends to serve as a good intermediate host in parasite transmission. Second, by conducting simulation experiments with different food web models and extinction scenarios, I demonstrated that the reduction in food web robustness after considering parasites is mainly contributed by the life cycle constrain of parasites. The finding further demonstrates that parasites are prone to secondary extinctions and their extinctions occur earlier than those involving non-parasite species. The evident vulnerability nature of parasite to species loss designates parasite a proper leading indicators of food web integrity. Lastly, with the extension of a previously developed methodology, a new approach is presented and used to quantify the interaction structure of a food web and consequently the topological importance of species when the food web is viewed as a signed digraph. This method is also capable to quantify the strength of inter-specific interaction as well as in what way species interact with each other after counting both direct and indirect cascades in both top-down and bottom-up directions. As it has the potential to quantify a wide range of ecological interactions, its further application on revealing the interaction structures between parasites and other functional groups in food web with parasites is evidently achievable.

Albert, R., H. Jeong, and A. L. Barabasi. 2000. Error and attack tolerance of complex networks. Nature 406:378-382.
Allesina, S., and A. Bodini. 2004. Who dominates whom in the ecosystem? Energy flow bottlenecks and cascading extinctions. Journal of Theoretical Biology 230:351-358.
Allesina, S., and M. Pascual. 2009. Googling food webs: can an eigenvector measure species' importance for coextinctions? PLoS Computational Biology 5.
Amundsen, P. A., K. D. Lafferty, R. Knudsen, R. Primicerio, A. Klemetsen, and A. M. Kuris. 2009. Food web topology and parasites in the pelagic zone of a subarctic lake. Journal of Animal Ecology 78:563-572.
Arias-Gonzalez, J. E., and S. Morand. 2006. Trophic functioning with parasites: a new insight for ecosystem analysis. Marine Ecology-Progress Series 320:43-53.
Barabasi, A.-L. 2009. Scale-free networks: a decade and beyond. Science 325:412-413.
Bascompte, J. 2007. Networks in ecology. Basic and Applied Ecology 8:485-490.
Bascompte, J. 2009. Disentangling the web of life. Science 325:416-419.
Bascompte, J., and D. B. Stouffer. 2009. The assembly and disassembly of ecological networks. Philosophical Transactions of the Royal Society B-Biological Sciences 364:1781-1787.
Baum, J. K., and B. Worm. 2009. Cascading top-down effects of changing oceanic predator abundances. Journal of Animal Ecology 78:699-714.
Baxter, C. V., K. D. Fausch, M. Murakami, and P. L. Chapman. 2004. Fish invasion restructures stream and forest food webs by interrupting reciprocal prey subsidies. Ecology 85:2656-2663.
Beckerman, A. P., and O. L. Petchey. 2009. Infectious food webs. Journal of Animal Ecology 78:493-496.
Bhuthimethee, M., N. O. Dronen, and W. H. Neill. 2005. Metazoan parasite communities of sentinel bluegill caged in two urbanizing streams, San Antonio, Texas. Journal of Parasitology 91:1358-1367.
Bonacich, P. 1987. Power and centrality - a family of measures. American Journal of Sociology 92:1170-1182.
Borgatti, S. P., M. G. Everett, and L. C. Freeman. 2002. Ucinet for Windows: Software for Social Network Analysis. Analytic Technologies, Harvard.
Bush, A. O., J. C. Fernandez, G. W. Esch, and S. J. R. 2001. Parasitism: the diversity and ecology of animal parasites. Cambridge University Press, Cambridge, UK.
Byers, J. E. 2009. Including parasites in food webs. Trends in Parasitology 25:55-57.
Callaway, D. S., M. E. J. Newman, S. H. Strogatz, and D. J. Watts. 2000. Network robustness and fragility: percolation on random graphs. Physical Review Letters 85:5468-5471.
Carpenter, S. R., W. A. Brock, J. J. Cole, J. F. Kitchell, and M. L. Pace. 2008. Leading indicators of trophic cascades. Ecology Letters 11:128-138.
Cattin, M. F., L. F. Bersier, C. Banasek-Richter, R. Baltensperger, and J. P. Gabriel. 2004. Phylogenetic constraints and adaptation explain food-web structure. Nature 427:835-839.
Choisy, M., S. P. Brown, K. D. Lafferty, and F. Thomas. 2003. Evolution of trophic transmission in parasites: Why add intermediate hosts? American Naturalist 162:172-181.
Christensen, V., and S. Lai. 2007. Ecopath with Ecosim 6: the sequel. . The Sea Around Us Project Newsletter 43:1-4.
Christensen, V., and C. J. Walters. 2004. Ecopath with Ecosim: methods, capabilities and limitations. Ecological Modelling 172:109-139.
Chubb, J. C., M. A. Ball, and G. A. Parker. 2010. Living in intermediate hosts: evolutionary adaptations in larval helminths. Trends in Parasitology 26:93-102.
Cohen, J. E., T. Jonsson, and S. R. Carpenter. 2003. Ecological community description using the food web, species abundance, and body size. Proceedings of the National Academy of Sciences of the United States of America 100:1781-1786.
Cohen, J. E., and C. M. Newman. 1985. A stochastic-theory of community food webs .1. models and aggregated data. Proceedings of the Royal Society of London Series B-Biological Sciences 224:421-448.
Cohen, J. E., S. L. Pimm, P. Yodzis, and J. Saldana. 1993. Body sizes of animal predators and animal prey in food webs. Journal of Animal Ecology 62:67-78.
Dambacher, J. M., H. W. Li, and P. A. Rossignol. 2003a. Qualitative predictions in model ecosystems. Ecological Modelling 161:79-93.
Dambacher, J. M., H. K. Luh, H. W. Li, and P. A. Rossignol. 2003b. Qualitative stability and ambiguity in model ecosystems. American Naturalist 161:876-888.
Dobson, A., K. D. Lafferty, A. M. Kuris, R. F. Hechinger, and W. Jetz. 2008. Homage to Linnaeus: How many parasites? How many hosts? Proceedings of the National Academy of Sciences of the United States of America 105:11482-11489.
Dobson, A., D. Lodge, J. Alder, G. S. Cumming, J. Keymer, J. McGlade, H. Mooney, J. A. Rusak, O. Sala, V. Wolters, D. Wall, R. Winfree, and M. A. Xenopoulos. 2006. Habitat loss, trophic collapse, and the decline of ecosystem services. Ecology 87:1915-1924.
Duffy, J. E. 2002. Biodiversity and ecosystem function: the consumer connection. Oikos 99:201-219.
Dunne, J. A., and R. J. Williams. 2009. Cascading extinctions and community collapse in model food webs. Philosophical Transactions of the Royal Society B-Biological Sciences 364:1711-1723.
Dunne, J. A., R. J. Williams, and N. D. Martinez. 2002a. Food-web structure and network theory: the role of connectance and size. Proceedings of the National Academy of Sciences of the United States of America 99:12917-12922.
Dunne, J. A., R. J. Williams, and N. D. Martinez. 2002b. Network structure and biodiversity loss in food webs: robustness increases with connectance. Ecology Letters 5:558-567.
Dunne, J. A., R. J. Williams, and N. D. Martinez. 2004. Network structure and robustness of marine food webs. Marine Ecology-Progress Series 273:291-302.
Ebenman, B., and T. Jonsson. 2005. Using community viability analysis to identify fragile systems and keystone species. Trends in Ecology & Evolution 20:568-575.
Ebenman, B., R. Law, and C. Borrvall. 2004. Community viability analysis: the response of ecological communities to species loss. Ecology 85:2591-2600.
Eklof, A., and B. Ebenman. 2006. Species loss and secondary extinctions in simple and complex model communities. Journal of Animal Ecology 75:239-246.
Estrada, E. 2007. Food webs robustness to biodiversity loss: the roles of connectance, expansibility and degree distribution. Journal of Theoretical Biology 244:296-307.
Frank, K. T., B. Petrie, J. S. Choi, and W. C. Leggett. 2005. Trophic cascades in a formerly cod-dominated ecosystem. Science 308:1621-1623.
Getz, W. M. 2009. Disease and the Dynamics of Food Webs. PLoS Biol 7:e1000209.
Gilbert, A. J. 2009. Connectance indicates the robustness of food webs when subjected to species loss. Ecological Indicators 9:72-80.
Grosholz, E. D., G. M. Ruiz, C. A. Dean, K. A. Shirley, J. L. Maron, and P. G. Connors. 2000. The impacts of a nonindigenous marine predator in a California bay. Ecology 81:1206-1224.
Hatcher, M. J., J. T. A. Dick, and A. M. Dunn. 2006. How parasites affect interactions between competitors and predators. Ecology Letters 9:1253-1271.
Hernandez, A. D., J. F. Bunnell, and M. V. K. Sukhdeo. 2007. Composition and diversity patterns in metazoan parasite communities and anthropogenic disturbance in stream ecosystems. Parasitology 134:91-102.
Hernandez, A. D., and M. V. K. Sukhdeo. 2008. Parasites alter the topology of a stream food web across seasons. Oecologia 156:613-624.
Holt, R. D., and J. H. Lawton. 1994. The ecological consequences of shared natural enemies. Annual Review of Ecology and Systematics 25:495-520.
Hosack, G. R., H. W. Li, and P. A. Rossignol. 2009. Sensitivity of system stability to model structure. Ecological Modelling 220:1054-1062.
Hudson, P. J., A. P. Dobson, and K. D. Lafferty. 2006. Is a healthy ecosystem one that is rich in parasites? Trends in Ecology & Evolution 21:381-385.
Huxham, M., S. Beaney, and D. Raffaelli. 1996. Do parasites reduce the chances of triangulation in a real food web? Oikos 76:284-300.
Huxham, M., and D. Raffaelli. 1995. Parasites and food web patterns. Journal of Animal Ecology 64:168-176.
Ings, T. C., J. M. Montoya, J. Bascompte, N. Bluthgen, L. Brown, C. F. Dormann, F. Edwards, D. Figueroa, U. Jacob, J. I. Jones, R. B. Lauridsen, M. E. Ledger, H. M. Lewis, J. M. Olesen, F. J. F. van Veen, P. H. Warren, and G. Woodward. 2009. Ecological networks - beyond food webs. Journal of Animal Ecology 78:253-269.
Jennings, S., and M. J. Kaiser. 1998. The effects of fishing on marine ecosystems. Advances in Marine Biology, Vol 34 34:201-+.
Johnson, P. T. J., A. Dobson, K. D. Lafferty, D. J. Marcogliese, J. Memmott, S. A. Orlofske, R. Poulin, and D. W. Thieltges. 2010. When parasites become prey: ecological and epidemiological significance of eating parasites. Trends in Ecology & Evolution 25:362-371.
Jordan, F. 2009. Keystone species and food webs. Philosophical Transactions of the Royal Society B-Biological Sciences 364:1733-1741.
Jordan, F., Z. Benedek, and J. Podani. 2007. Quantifying positional importance in food webs: A comparison of centrality indices. Ecological Modelling 205:270-275.
Jordan, F., W. C. Liu, and A. J. Davis. 2006. Topological keystone species: measures of positional importance in food webs. Oikos 112:535-546.
Jordan, F., W. C. Liu, and A. Mike. 2009. Trophic field overlap: A new approach to quantify keystone species. Ecological Modelling 220:2899-2907.
Jordan, F., W. C. Liu, and F. J. F. van Veen. 2003. Quantifying the importance of species and their interactions in a host-parasitoid community. Community Ecology 4:79-88.
Jordan, F., W. C. Liu, and T. Wyatt. 2005. Topological constraints on the dynamics of wasp-waist ecosystems. Journal of Marine Systems 57:250-263.
Jordan, F., and G. Osvath. 2009. The sensitivity of food web topology to temporal data aggregation. Ecological Modelling 220:3141-3146.
Jordan, F., and I. Scheuring. 2002. Searching for keystones in ecological networks. Oikos 99:607-612.
Jordan, F., A. Takacs-Santa, and I. Molnar. 1999. A reliability theoretical quest for keystones. Oikos 86:453-462.
Jordano, P., J. Bascompte, and J. M. Olesen. 2003. Invariant properties in coevolutionary networks of plant-animal interactions. Ecology Letters 6:69-81.
Kondoh, M. 2003. Foraging adaptation and the relationship between food-web complexity and stability. Science 299:1388-1391.
Kuris, A. M., R. F. Hechinger, J. C. Shaw, K. L. Whitney, L. Aguirre-Macedo, C. A. Boch, A. P. Dobson, E. J. Dunham, B. L. Fredensborg, T. C. Huspeni, J. Lorda, L. Mababa, F. T. Mancini, A. B. Mora, M. Pickering, N. L. Talhouk, M. E. Torchin, and K. D. Lafferty. 2008. Ecosystem energetic implications of parasite and free-living biomass in three estuaries. Nature 454:515-518.
Lafferty, K. D. 1999. The evolution of trophic transmission. Parasitology Today 15:111-115.
Lafferty, K. D. 2008. Ecosystem consequences of fish parasites. Journal of Fish Biology 73:2083-2093.
Lafferty, K. D., S. Allesina, M. Arim, C. J. Briggs, G. De Leo, A. P. Dobson, J. A. Dunne, P. T. J. Johnson, A. M. Kuris, D. J. Marcogliese, N. D. Martinez, J. Memmott, P. A. Marquet, J. P. McLaughlin, E. A. Mordecai, M. Pascual, R. Poulin, and D. W. Thieltges. 2008. Parasites in food webs: the ultimate missing links. Ecology Letters 11:533-546.
Lafferty, K. D., A. P. Dobson, and A. M. Kuris. 2006. Parasites dominate food web links. Proceedings of the National Academy of Sciences of the United States of America 103:11211-11216.
Lafferty, K. D., and A. M. Kuris. 2002. Trophic strategies, animal diversity and body size. Trends in Ecology & Evolution 17:507-513.
Lafferty, K. D., and A. M. Kuris. 2009. Parasites reduce food web robustness because they are sensitive to secondary extinction as illustrated by an invasive estuarine snail. Philosophical Transactions of the Royal Society B-Biological Sciences 364:1659-1663.
Leaper, R., and M. Huxham. 2002. Size constraints in a real food web: predator, parasite and prey body-size relationships. Oikos 99:443-456.
Levine, S. 1980. Several measures of trophic structure applicable to complex food webs. Journal of Theoretical Biology 83:195-207.
Levine, S. H. 1976. Competitive Interactions in ecosystems. American Naturalist 110:903-910.
Lin, H. J., K. T. Shao, J. S. Hwang, W. T. Lo, I. J. Cheng, and L. H. Lee. 2004. A trophic model for Kuosheng Bay in northern Taiwan. Journal of Marine Science and Technology-Taiwan 12:424-432.
Marcogliese, D. J. 2001. Pursuing parasites up the food chain: Implications of food web structure and function on parasite communities in aquatic systems. Acta Parasitologica 46:82-93.
Marcogliese, D. J. 2002. Food webs and the transmission of parasites to marine fish. Parasitology 124:S83-S99.
Marcogliese, D. J. 2005. Parasites of the superorganism: are they indicators of ecosystem health? International Journal for Parasitology 35:705-716.
Marcogliese, D. J., and D. K. Cone. 1997. Food webs: a plea for parasites. Trends in Ecology & Evolution 12:320-325.
McCann, K. S. 2000. The diversity-stability debate. Nature 405:228-233.
Melian, C. J., and J. Bascompte. 2002. Complex networks: two ways to be robust? Ecology Letters 5:705-708.
Memmott, J., H. C. J. Godfray, and I. D. Gauld. 1994. The structure of a tropical host parasitoid community. Journal of Animal Ecology 63:521-540.
Menge, B. A. 1995. Indirect effects in marine rocky intertidal Interaction webs - patterns and importance. Ecological Monographs 65:21-74.
Montoya, J. M., S. L. Pimm, and R. V. Sole. 2006. Ecological networks and their fragility. Nature 442:259-264.
Montoya, J. M., and R. V. Sole. 2003. Topological properties of food webs: from real data to community assembly models. Oikos 102:614-622.
Montoya, J. M., G. Woodward, M. C. Emmerson, and R. V. Sole. 2009. Press perturbations and indirect effects in real food webs. Ecology 90:2426-2433.
Mouillot, D., B. R. Krasnov, and R. Poulin. 2008. High intervality explained by phylogenetic constraints in host-parasite webs. Ecology 89:2043-2051.
Mouritsen, K. N., and R. Poulin. 2002. Parasitism, community structure and biodiversity in intertidal ecosystems. Parasitology 124:S101-S117.
Mouritsen, K. N., and R. Poulin. 2003. Parasite-induced trophic facilitation exploited by a non-host predator: a manipulator's nightmare. International Journal for Parasitology 33:1043-1050.
Mouritsen, K. N., and R. Poulin. 2010. Parasitism as a determinant of community structure on intertidal flats. Marine Biology 157:201-213.
Muller, C. B., I. C. T. Adriaanse, R. Belshaw, and H. C. J. Godfray. 1999. The structure of an aphid-parasitoid community. Journal of Animal Ecology 68:346-370.
Newman, M. E. J. 2003. The structure and function of complex networks. Siam Review 45:PII S0036144503424804.
Packer, C., R. D. Holt, P. J. Hudson, K. D. Lafferty, and A. P. Dobson. 2003. Keeping the herds healthy and alert: implications of predator control for infectious disease. Ecology Letters 6:797-802.
Palm, H. W., and S. Ruckert. 2009. A new approach to visualize ecosystem health by using parasites. Parasitology Research 105:539-553.
Parker, G. A., J. C. Chubb, M. A. Ball, and G. N. Roberts. 2003. Evolution of complex life cycles in helminth parasites. Nature 425:480-484.
Pedersen, A. B., and A. Fenton. 2007. Emphasizing the ecology in parasite community ecology. Trends in Ecology & Evolution 22:133-139.
Petchey, O. L., A. P. Beckerman, J. O. Riede, and P. H. Warren. 2008a. Size, foraging, and food web structure. Proceedings of the National Academy of Sciences 105:4191-4196.
Petchey, O. L., A. Eklof, C. Borrvall, and B. Ebenman. 2008b. Trophically unique species are vulnerable to cascading extinction. American Naturalist 171:568-579.
Pimm, S. L., J. H. Lawton, and J. E. Cohen. 1991. Food web patterns and their consequences. Nature 350:669-674.
Poulin, R. 1995. Phylogeny, ecology, and the richness of parasite communities in vertebrates. Ecological Monographs 65:283-302.
Poulin, R. 1999. The functional importance of parasites in animal communities: many roles at many levels? International Journal for Parasitology 29:903-914.
Poulin, R. 2007. Are there general laws in parasite ecology? Parasitology 134:763-776.
Poulin, R. 2010. Network analysis shining light on parasite ecology and diversity. Trends in Parasitology 26:492-498.
Poulin, R., and S. Morand. 2000. The diversity of parasites. Quarterly Review of Biology 75:277-293.
Proulx, S. R., D. E. L. Promislow, and P. C. Phillips. 2005. Network thinking in ecology and evolution. Trends in Ecology & Evolution 20:345-353.
Quince, C., P. G. Higgs, and A. J. McKane. 2005. Deleting species from model food webs. Oikos 110:283-296.
Randhawa, H. S., and R. Poulin. 2010. Determinants of tapeworm species richness in elasmobranch fishes: untangling environmental and phylogenetic influences. Ecography 33:866-877.
Rott, A. S., and H. C. J. Godfray. 2000. The structure of a leafminer-parasitoid community. Journal of Animal Ecology 69:274-289.
Sole, R. V., and J. M. Montoya. 2001. Complexity and fragility in ecological networks. Proceedings of the Royal Society B-Biological Sciences 268:2039-2045.
Sole, R. V., J. M. Montoya, M. Pascual, and J. A. Dunne. 2006. Ecological network meltdown from habitat loss and fragmentation. Pages 305-323 in M. Pascual and J. A. Dunne, editors. Ecological Networks: Linking Structure to Dynamics in Food Webs. Oxford University Press, New York.
Staniczenko, P. P. A., O. T. Lewis, N. S. Jones, and F. Reed-Tsochas. 2010. Structural dynamics and robustness of food webs. Ecology Letters 13:891-899.
Stephenson, K., and M. Zelen. 1989. Rethinking centrality - methods and examples. Social Networks 11:1-37.
Thieltges, D. W., X. de Montaudouin, B. Fredensborg, K. T. Jensen, J. Koprivnikar, and R. Poulin. 2008. Production of marine trematode cercariae: a potentially overlooked path of energy flow in benthic systems. Marine Ecology-Progress Series 372:147-155.
Thompson, R. M., K. N. Mouritsen, and R. Poulin. 2005. Importance of parasites and their life cycle characteristics in determining the structure of a large marine food web. Journal of Animal Ecology 74:77-85.
Torchin, M. E., K. D. Lafferty, and A. M. Kuris. 2002. Parasites and marine invasions. Parasitology 124:S137-S151.
Uchida, S., and B. Drossel. 2007. Relation between complexity and stability in food webs with adaptive behavior. Journal of Theoretical Biology 247:713-722.
Ulanowicz, R. E., and C. J. Puccia. 1990. Mixed trophic impacts in ecosystems. Coenoses 5:7-16.
Valtonen, E. T., D. J. Marcogliese, and M. Julkunen. 2010. Vertebrate diets derived from trophically transmitted fish parasites in the Bothnian Bay. Oecologia 162:139-152.
Vasas, V., and F. Jordan. 2006. Topological keystone species in ecological interaction networks: considering link quality and non-trophic effects. Ecological Modelling 196:365-378.
Vazquez, D. P. 2005. Degree distribution in plant-animal mutualistic networks: forbidden links or random interactions? Oikos 108:421-426.
Vazquez, D. P., C. J. Melian, N. M. Williams, N. Bluthgen, B. R. Krasnov, and R. Poulin. 2007. Species abundance and asymmetric interaction strength in ecological networks. Oikos 116:1120-1127.
Vazquez, D. P., R. Poulin, B. R. Krasnov, and G. I. Shenbrot. 2005. Species abundance and the distribution of specialization in host-parasite interaction networks. Journal of Animal Ecology 74:946-955.
Wallach, A. D., B. R. Murray, and A. J. O'Neill. 2009. Can threatened species survive where the top predator is absent? Biological Conservation 142:43-52.
Warren, C. P., M. Pascual, K. D. Lafferty, and A. M. Kuris. 2010. The inverse niche model for food webs with parasites. Theoretical Ecology published online:doi:10.1007/s12080-12009-10069-x.
Wasserman, S., and K. Faust. 1994. Social network analysis: methods and applications. Cambridge University Press, Cambridge, UK.
Williams, R. J., and N. D. Martinez. 2000. Simple rules yield complex food webs. Nature 404:180-183.
Woodward, G., B. Ebenman, M. Emmerson, J. M. Montoya, J. M. Olesen, A. Valido, and P. H. Warren. 2005. Body size in ecological networks. Trends in Ecology & Evolution 20:402-409.
Wootton, J. T. 1994a. The nature and consequences of indirect effects in ecological communities. Annual Review of Ecology and Systematics 25:443-466.
Wootton, J. T. 1994b. Predicting direct and indirect effects - an integrated approach using experiments and path-analysis. Ecology 75:151-165.
Yamaguti, S. 1975. Synoptical review of life histories of digenetic trematodes of vertebrates. Keigaku Publishing, Tokyo.
Yodzis, P. 2000. Diffuse effects in food webs. Ecology 81:261-266.
Yodzis, P., and K. O. Winemiller. 1999. In search of operational trophospecies in a tropical aquatic food web. Oikos 87:327-340.