CPeople diet to look more attractive. Fish diet to avoid being beaten up, thrown out of th

C

Peoplediettolookmoreattr active.Fishdiettoavoidbeingbeatenup,thrownoutoftheirsocialgroup,andgettingeatenasaresult.Thatisthefascinatingconclusionofthelatestr esearchintofishbehavior.byateamofAustr alianscientists.

Theresearchteamhavediscoveredthatsubordinatefishvoluntarilydiettoavoidchallengingtheirlargercompetitors.“Instudyinggobieswenoticedthatonlythelargesttwoindividuals,amaleandfemale,hadbreeding(繁殖)rightswithinthegroup,”explainsMarianWong.“Allothergroupmembersarenonbreedingfemales,eachbeing5-10%smallerthanitsnextlargestcompetitor.Wewantedtofindouthowtheymaintainthisprecisesizeseparation.”

Thereasonforthesizedifferencewaseasytosee.onceasubordinatefishgrowstowithin5-10%ofthesizeofitslargercompetitor,itcausesafightwhichusuallyendsinthesmallergobybeingdrivenawayfromthegroup.Moreoftenthannot,theevictedfishistheneatenup.

Itappearedthatthesmallerfishwerekeepingthemselvessmallinordertoavoidchallengingthebossfish.Whethertheydidsovoluntarily,byrestr aininghowmuchtheyate,wasnotclear.Theresearchteamdecidedtodoanexperiment.Theytr iedtofattenupsomeofthesubordinategobiestoseewhathappened.Totheirsurprise,thegobiessimplyrefusedtheextr afoodtheywereoffered,clearlypreferringtoremainsmallandavoidfights,overhavingafeast.

Thediscoverychallengesthetr aditionalscientificviewofhowbossindividualskeeptheirpositioninagroup.Previouslyitwasthoughtthatlargeindividualssimplyusedtheirweightandsizetothreatentheirsubordinatesandtakemoreofthefoodforthemselves,sokeepingtheircompetitorssmall.

Whilethehabitsofgobiesmayseemalittlemysterious,Dr.Wongexplainsthatunderstandingtherelationshipsbetweenbossandsubordinateanimalsisimportanttounderstandinghowhierarchical(等级的)societiesremainstable .

Theresearchhasprovedthefactthatvoluntarydietingisahabitfarfromexclusivetohumans.“Asyet,welackacompleteunderstandingofhowwidespreadthevoluntaryreductionoffoodintakeisinnature,”theresearcherscomment.“Dataonhumandietingsuggeststhat,whilehumansgenerallydiettoimprovehealthorincreaseattr activeness,rarelydoesitimprovelong-termhealthandmalesregularlypreferfemalesthatarefatterthanthefemales’ownideal.”

65.Whenagobygrowstowithin5-10%ofthesizeofitslargercompetitor,it.

A.facesdangerB.hasbreedingrights

C.eatsitscompetitorD.leavesthegroupitself