perspectivecentrality and uniqueness of species from the network

摘要: Identifyingimportantspeciesformaintainingeco-system functions is a challenge in ecology. Sincespecies are components of food webs, one way toconceptualize and quantify species importance isfrom network perspective. The ofa can be quantified by measuring the cen-trality its position web, because acentral node may have greater influence onothersinthenetwork.Aspeciesmayalsobeimpor-tantbecauseithasauniquenetworkposition,suchthat loss cannot easily compensated. There-fore, for web to robust, we hypothesizethat central must functionally redun-dant terms their position. In thispaper, test our hypothesis analysing thePrince William Sound ecosystem. We found thatspecies centrality uniqueness negativelycorrelated,and such an observation isalsocarriedover other webs.Keywords: importance; centrality;uniqueness; web1. INTRODUCTIONOne ecology identify importantspecies [1,2]. Since embedded webs oftrophic interactions, possible approach impor-tance speciesin [3]. A with high canaffect many others, maybe also more quickly, viastrong direct indirect effects [4,5]. These includevertical top-down bottom-updirections [6], horizontal like exploitiveand apparent competitions [7].Different different ecological roles andtheir reflect these [8,9]. Forinstance, there producers, top predators omni-vores. Beyond treating as proxy speciesimportance, it emerging interest knowhow similar neighbourhoods afood [10]. importantbecause has unique neigh-bourhood that poorly overlaps others. Asa consequence, this kind arenot replaceable, trophic functionsare not taken over others.If ecosystem functioning unit onlyone species, then intuition suggests itis prone failure when isremoved. Therefore, itshould several lossof compensated Thus, weargue twoopposing characteristics existing ecosystems. Inthis paper, analyse Prince Sound(PWS) [11] illustrative example andask, ‘are unique?’, gen-eralityof finding using webs.We notethat dynamic analysis onlyfocuses on topological structure.2. MATERIAL AND METHODS