Preferential prey sharing among kin not found in the social huntsman spider, Delena cancerides (Araneae: Sparassidae)

2011·5.1 MB·English

by  Anthony Auletta

2011.TheJournalofArachnology39:258-262
Preferential prey sharing among kin not found in the social huntsman spider, Delena cancerides
(Araneae: Sparassidae)
AnthonyAuletta: DepartmentofEntomology, Cornell University, Ithaca, NewYork 14853; DepartmentofBiological
Sciences, WesternCarolina University, Cullowhee, North Carolina 28723, USA
LindaS.Rayor': DepartmentofEntomology,CornellUniversity,Ithaca,NewYork 14853USA;Evolution,Ecologyand
Genetics, AustralianNational University, Canberra, Australian CapitalTerritory0200, Australia
Abstract. Although the benefitsofgroupforagingareimportantforevolutionofsocialityinspiders, thefactorsthat
intluencegroup-levelbenefitsofpreysharinginsocialspidersarestillpoorlyunderstood.Intheunusualtransitionalsocial
spiderDelenacanceridesWaickenaer1837(Sparassidae),preysharingalmostcertainlyoccursoccasionallyamongnon-kin
inthewild,andsowetestedtheeffectsofkinrelationshipsandfamiliarityontheamountofpreyconsumedinthisspecies.
Todeterminewhethertheamountofpreysharingincreasedwithrelatednessorwithfamiliarity,wefedtreatmentgroups
containingspiderlingsofvaryingrelatednessandfamiliarityasinglepreyitemandmeasuredtheamountofweightgained
by sharinggroups. Wefound noeffectofrelatednessorfamiliarityonthe amountofpreyconsumed by prey-sharing
groupsofD.cancerides.Increaseddurationofsharing,numberandageofthespidersinvolved,andsizeofthepreyitemall
increasedtheamountofpreyconsumed.Thebenefitsofpreysharinginthisspecieslikelyoverwhelmanypossibleinclusive
fitnessbenefitsderivedfromkindiscriminationinthishighlyoutbredsocialspider. Hence,werejectthehypothesisthat
groupsofkinconsumedproportionatelylargeramountsofpreybiomassthangroupsofnon-kin,asproposedbySchneider
andBildein2008withStegodyphuslineatusLatreille 1817(Eresidae).
Keywords: Cooperativeforaging,kinrecognition,socialspiders,group-living,nutrition
Benefits ofcooperative foraginghavebeen proposed to be siblings during the first 30 days following hatching, after
thedrivingforcebehindtheevolutionofsocialbehaviorina which the spiders disperse during the fifth instar and
diverse array of animals, from wild canids to predatory apparently do not forage communally again (Schneider
hemipterans (Travers 1993; Creel & Creel 1995; Krause & 1995; Schneider& Lubin 1997). When dispersing, S. lineatus
Ruxton2002).Cooperativehuntingallowsthecaptureofprey display a high level of philopatry, and individuals from
too largeforsolitary individualsto handle, and preysharing differentnatalgroupstendtodisperseinoppositedirectionsin
leads to increased foraging success and higher fitness for a given microhabitat (Lubin et al. 1998). Therefore, it is
group-livingindividuals,althoughtheaverageamountoffood unlikelythatS. lineatusjuvenileswouldeverbeinasituation
that an individual consumes during each predation event wheretheywouldpotentiallysharepreyitemswithunrelated
mightbesmaller(Clark& Mangel 1986; Caracoetal. 1995). or unfamiliar conspecifics. Similarly, prey sharing among
Similargroup foraging benefits are thought to be one ofthe unrelatedconspecifics is unlikelyin highly social cooperative
majoradvantages ofgrouplivingin social spiders (Araneae) spidersexhibitinglowratesofimmigrationandhighlevelsof
(Buskirk 1981; Rypstra & Tirey 1991; Whitehouse & Lubin inbreeding(Aviles 1997; Lubin&Bilde2007).
2005; Lubin& Bilde2007). However, manyquestionsremain Like S. lineatus, the social spider Delena cancerides
about theeffects ofgroupcomposition on theextentofprey Waickenaer 1837 (Sparassidae) is known to be capable of
sharingwithingroups. kinrecognition(Beavisetal.2007;Yipetal.2009). However,
Schneider and Bilde (2008) found that in the subsocial in contrast to S. lineatus, it is probable that immature D.
spider Stegodyphus lineatus Latreille 1817 (Eresidae), groups cancerides occasionally share prey items with non-kin in the
ofclose kin share more prey biomass with each other than field. Thus, in the present study, we set out to determine
groupsofnon-kin,regardlessofthefamiliarityofindividuals whether different amounts of prey biomass are shared by
inthegroup.Theauthorshypothesizedthatindividualspiders groups of D. cancerides depending on the relatedness and
couldpreferentiallydecreasetheamountofdigestiveenzymes familiarityofalloftheindividualsinthegroup.
they would inject into a prey item when sharing with non- Delena cancerides is an unusual transitional social spider
relatives,whichwouldexplaintheobservedpatterns.Previous from Australia that shares subsocial and cooperative spider
work had shownthatS. lineatusresponddifferentiallyto kin traits(L.S.Rayorunpubl.data).Individualsofthisspecieslive
by increasedcannibalism ofnon-kin underfoodstress (Bilde in kin-based groups of up to 300 individuals under the
&Lubin2001),butSchneiderandBilde(2008)werethefirstto exfoliating bark of dead trees, and these groups typically
indicate that the quantity of prey shared in groups was consist of one adult female and one to four cohorts of
influenced bykin recognition. immature offspring (Rowell & Aviles 1995; L.S. Rayor
However,unrelatedS. lineatusspiderlingsdonotshareprey unpubl. data).
naturally. This species is only known to share prey with Delena canceridespopulations are patchily distributed and
inhabitatswheretherearemultiplesuitabletreesforretreats,
‘Correspondingauthor. E-mail: [email protected] such that D. cancerides colonies are frequently found on
258
AULETTA&RAYOR—PREYSHARINGNOTPREFERENTIALAMONGKIN 259
neighboring trees (L.S. Rayor iinpubl. data). As the spiders Spiders digest their food externally by secreting digestive
forage for prey outside their retreat, sometimes traveling as enzymesintothebodyofthepreyitemandthenimbibingthe
muchas5-10mbeforereturningtotheretreatinthemorning liquefiedremains(Foelix2011).Sincethespidersleavebehind
(Yip&Rayor2011),youngspidersoccasionallyreturntothe the indigestible parts ofprey items, the amount ofbiomass
incorrect retreat (Yip and Rayor 2011). Although initial that spiders ingest from their prey can be measured by
studiesonthespeciesindicatedthatD. cancerideswerehighly recordingtheweightofthepreyitembeforeandafteritisfed
aggressivetowardsconspecificsfromothercolonies(Rowell& onbyagroupofspiders(Tso&Severinghaus 1998).
Aviles 1995),morerecentstudies(Beavisetal.2007;Yipetal. Toassessthepossibledifferential benefitsforprey-sharing
2009) demonstrated that youngerindividuals below a certain groups ofdifferent relationships and levels offamiliarity, we
sizethreshold(<seventhinstar)werereadilyacceptedintoalien randomly assigned individuals from 19 laboratory source
colonieswithoutovertaggression.Thesefindingssuggestthat coloniestofourexperimentaltreatments:
einndciovuindtuearlisnignajunvyenoinleescoflroonmyhoatvheera,ruenarseolnaatbeldepcroolboanbiielsityanodf • fRerloamteadsiFnagmlieliclaurtc(hRFa)nd=thastpihdeardsbteheantrweearreedfutlolgestihbelringisn
pmiYuonanotdptAueiuenmvnbltiolgyid.anu3lasgld0lpyais%tdjsafeuho)rova,fserr,naaiaiglnlellegsetfpahepeswoecrpuidaeiagiyydlnhelgwrfyisi,ret,tvohbeimspentrntthleesheefyesmiist.nrsefht(trhaireerneqialunttaeghbn(eotYorifcaipconturo&rmtrshyReo(aifLnfy.ioiSean.lrpdcpRr2rwe0aoa1hyx1seoi)enr.-d • stffiRihserrboeloollammiastntaegitmtsdohheneefUunrcnnaaeotftggmiaalegmlaitschlsisoeainilcycaneorgwnl(ebyae(irtrReictUmlhtr.um)heteeicdnh=istaerbtcousedoptliunydcdteehardafsittntesohtrthaaeatrdath)cehbywaeeonehrtdnahedesrraeealpdimsiaseorerredacgfttueelilddynl
growth)frompreysharingattheretreatduetothepresenceof beforetheexperimentsbeganasfourthinstarspiderlings.
oldersiblings,whichcancapturelargerpreyitems(E.C. Yip • Unrelated Familiar (UF) = spiders that were 100%
unpIunbtlh.isdsattuad)y.,wetestedwhetherSchneiderandBilde’s(2008) uhnardelbaeteendtsoepaallraottehderfrsopimdetrhseiirnntahtealsacmoelognireosupi,mbmuetdiwahtieclhy
finding that both groups of familiar and unfamiliar kin after they had emerged from the egg sac and reared
consumemorebiomasswhilesharingpreythangroupsofnon-
together.
kin could be extended to a spider species in which this • UnrelatedUnfamiliar(UU) = spidersthatwerealso 100%
atbhenehdatvuointorarlelaiacnttgeuedasltilenyddiobvciicdouurmasal.ss.sToTooftepesrtxeatyhmiiisntheeymptsohteihneesfgfiresoc,tuspwseofoeffxaarmmeililaintaeerdd- mounnerlneytlsaitnbetedrgoatdnou.caelldottoheeracshpidoetrhserinditrheectlgyrobuepfoarendthtehaetxpweerrie-
ity independent ofrelatedness, we repeated the experiments
with groups of unfamiliar-related and familiar-unrelated Each groupconsisted ofsix individual spiders, which were
spiders. We predicted that if Schneider and Bilde’s (2008) housedin 10 X 10 X 13cmplasticcages. Duetoinstancesof
results would also apply to D. cancerides, the spiders would individual mortality, some groups were reduced to five
sharemorepreybiomassingroupsofrelatedindividualsthan individuals. Priortogroupformationweweighedeachspider
theywouldingroupsofunrelatedindividuals. and minimized initial size differences between the spiders in
METHODS each group by purposefully forming groups ofspiders with
Study organisms.—We reared the specimens of Delena msiemnitlsarwhboednythweeisgphitdse.rsWreeacpheerdfothremefdoutrhtehipnrsetya-rsahanrdicngonetxipneureid-
cancerides used in this experiment in the laboratory from untilthespidersreachedtheseventhinstar,atwhichpointwe
July-December2009.Theyweredescendantsofwildindivid- determinedthemtobetoolargefortheexperiment.
uals originally collected in 2006 and 2008 from sites in Several minutes prior to each experimental trial, we
s(oRuotwheelalst&erAnviAluesstr1a9l9i5a;.GBreuceatuzsneertheitsals.pe2c0i0e6s),iswheigkhelpytodeuttabirleedd amneeasstuhreteidzetdhetthoetalspmiadesrssofintheeacehntirgerogurpoupwitohfpCreO-f2e,edainndg
long-termrecordsoftheoriginsandallcross-breedingevents spiderstothenearest0.0001 gusingaMettlerToledoAG285
foreachcolonyinordertomaintainoutbreeding.Thespiders electronicscale.Afterseveralminutes,whenthespidersbegan
livefor~2.5yranddonotreachsexualmaturityuntil~ 1yr, to recover from anesthesia, we weighed a single prey item
so the spiderlings used from 2008 wild-caught spiders were (eitheraflyorcricket)andplaceditintoeachgroup.Preytype
only the Fi generation in the laboratory, while spiderlings wasdeterminedbyspidersize, assmallerspiders(fourthand
from parents collected in 2006 were ~ F3 generation. We fifthinstars)captured housefliesmostreadily. Largerinstars
housedlaboratorycoloniesofspidersin9.5 and 19-1terraria (fifth-seventhinstars)weregivensarcophagidfliesorcrickets,
withsheetsofclearplexiglass“bark”affixed~2cmfromthe dependingonavailability.
glass to emulate their natural retreat structure. Prey items Oncethespidershadsuccessfullycapturedthepreyitem,we
included adult flesh flies {Neobellieria bullata Diptera; recordedthenumberofspiderssharingitevery 10minfor2h.
Sarcophagidae), common house crickets {Acheta domesticus During each observation, we also noted the behavior ofthe
Orthoptera:Gryllidae)andlargehouseflies(Muscadomestica spiders and recorded any solicitations for prey sharing or
Diptera: Muscidae). attempts to pull away from a sharing group. We recorded
Group benefi—ts of prey sharing relative to relatedness groupsasnothavingeatenduringatrialifthespidersdidnot
and familiarity. Our methodology closely follows that used successfullycapture the prey item within two hours, and we
by Schneider and Bilde (2008) in examining the effects of discarded these trials. After the 2-h observation period
relatednessandfamiliarityonsharinginStegodyphuslineatus. following successful prey capture, we separated any spiders
260 THEJOURNALOFARACHNOLOGY
—
that were still feeding from the prey, and recorded both the Table 1. Resultsofthelinearmixedmodelthatincorporatesall
combined post-feeding weight of the entire group and the trialsinwhichpreysharingoccurred.Themeasuredchangeinspider
remainsofthepreyitem. weightwasusedastheresponsevariable,andtreatmenttype,mean
Werepeatedthesetrialseveryseveraldaysover20wk,fora spider instar, initial prey item weight, and the calculated “sharing
nftroeirtpnoalelmicdoasiftefevfs1ee3nrf8ergnrotremopgultriphcosrauetipeenssgtrfihonreuoUptmhsFe1i8ntUrgtUehraeotutRmpreUsenatittnmareetnnahdtte.m3Re7TnFtor,etpi4rlne4icacrartetemaepeslsnietfc,arotou1em1rs tmsoierfgtenraiwitfecmii”ecgnanhwtttetrRye-pgveaua,islneuweededsr.aesbffyoiuxnesddpietdfoeferhctasvg.reoAsulilpgsnf.iafcitAcoasrntst,erewifisftekchststh(oe*n*e*tx)hceepiatnmidoiocnuantotef
samplesizes,weusedindividualgroupswithineachtreatment Factor df F P N
tfRoiUrmemsgulratoniudpplseUaUtrimagelsra:onuRpoFsfga3r.mo6ue7patsnimweoesfr,e4.Uu2Fs7edtgiramoeums.pesaAnfatoemfre2at.hn8e8oeftnid8m.e8so,0f TIMnreietaiaantlmspeprnietdyerweiingsthatr 11221322 29672...855560 <<000...1000005103*1***** 111333666
theexperiment,wecalculatedthepercentageoftrialsineach Sharingmetric 122 17.64 <0.0001*** 136
treatment during which prey sharing occurred. In between
wafeemeTeodkouinnigdtnettoroierfadrlpsem,rrienwtyeeocfwkoehedneestptuhheaemlrelgdrskopiiuinnpdsesphrriwspeiyptrohsorshpmaefarralilmlniylghinoaeoruvuiesrtneiytssfh,laeifdewfs.eeoctnuecsdeedptehaer TfsahacabTtrlhoeeerdrs1e)ip.nrwcealysudoenrdoiwsnhigtenhniefi“scshahanartriindngifgfemevreeetnnrtcisec”lbae(ststhweaedreinlnognwgemeeirtg,rhittchgeeafiftencwetod.
tpsf(eherRreeeFisdy,eeisnwRmogeoUfido,gmenhiltUsxtF,eah,dengdrolciorhnmueaUepanUargIn)emDosadiwpnneaidldsmseoarctstohosidenearsondtfpaaaralesryaoazacfmeherattlahlegenrrssdoep,fouifpmdeiecnretocsfflofuefisdcnpttivinrovdgeelaarvritsienm.iadtebinlIiatnenl wwc0b.eeoy1iim8gggp,hhra«ttorua=lpbgosals1tie3on6fbe,sdyisFzietxb=h{yesF0p1.ipg26drr47eeo3ry6us=)pw.asa1nN.sdof33erdg7ei1rdwr,ioeanucs«gtplsty=hoeoncrf3oe4rfc,rairevidPleciakftsef=eptedisrd0eew.nori2crst5e9h{b0fF)elwi.iteew4siT5egheho=entf
agsinprmioooduuerprdnse,trinoastfntoadsrhaactwrcreioenruagentmttechnfoatotdreotdrcyecppaeu,serarteifenididxteiidnamleeeaapfsfcruehecrytetsr.mwieaelTnigtowhset,qocufaaalnntcthudielfaymtseeadtamhneae g=11a336i60))n..e92td)h,banywitwthhaespsrpgeiaydienlroessdi(nPbg/y.m/tojshree=swp1ei5id6ge3hr,stn((mm=eeaa1nn36=,=P-00.<.003053.69090g0g,1,,««==
“sharing metric” foreach successful trial that reflected both Preysharingonlyoccurredin50.2%ofalltrials,andinthe
the number of spiders that shared the prey item and the trials for which prey sharing occurred, in 26.8% the sharing
durationofpreysharingthatoccurredbytotalingthenumber was forrelatively briefperiods (< 20 min). To minimize the
of spiders sharing during each ten-minute interval. For effect oftrials in which minimal prey sharing occurred, we
example, ifthree spiders shared prey for 50 min and then a reanalyzed the data including only those trials in which the
fourthjoinedtosharefor20min,thesharingmetricwouldbe prey item was shared for > 20 min. The new model {R~ =
(3 X 5)-t-(4 X 2) = 23. Thissharingmetricweencodedasa 0.75) shows that spiders still did not share morewith kin or
fixed effect in the model for groups in which therewas prey familiarindividuals(treatmenteffect.Table2);rather,spiders
sharing. Theresponseinallmodelswasthechangeinweight consumed more prey when the prey item was larger (initial
otrfantshfeorsmpaitdieorngirnouopr,dertotowhhiocmhogweenizaepplviaerdianacess.quaWree-raolosto pprreeyyw(emiegahntsefpfiedcetr.Tinasbtlaer2e)f,feactn.dToalbdleers2)p.idHeorwsecvoenrs,umtheedremowraes
incorporated prey type (flies or crickets) into the original no difference in the prey biomass consumed associated with
model inordertoconfirmthatithadnosignificanteffecton duration or the number of spiders sharing (sharing metric
theweightchangeofthespiders.Weexaminedthecorrelation effect.Table2)inthisanalysis.
between the change in weight of the spider group and the Giventhatspiderinstarhadaneffectontheamountofprey
changeinweightofthepreyitemusingalinearregression.All consumed by sharing groups, we also examined whether the
statisticalanalyseswereperformedinJMP8.0. amountofsharing(measuredbymeansharingmetric)differed
RESULTS relative to treatmentgroup byinstar. Whenthemean ageof
individuals in a group was fifth instar, we found that RF
Group benefit—s of prey sharing relative to relatedness groups sharedprey forlongerand in largergroups than UF
and familiarity, The levels of relatedness and familiarity groups,whiletherewerenosignificantdifferencesbetweenany
among spiders in a prey-sharing group did not significantly other treatments (Tukey Kramer HSD test, n = 34, all P >
influencetheamountofpreybiomassingestedbymembersof 0.07). Bythetimethemeanageofthespidersinagroupwas
the group. Although the linear mixed model applied to the sixthinstar,relatedspidersdidnotsharemorethanunrelated
dataforgroupsinwhichpreysharingoccurredwasagoodfit spiders, nor did familiar spiders share more than unfamiliar
forthesedata(i?“ =0.7314,P<0.001),thismodelshowedno spiders (Tukey-Kramer HSD test, n = 100, all P > 0.22;
significanteffectoftreatmentontheweightgainedbysharing Figure lA).
groups (treatment effect. Table 1). Groups of older spiders Although there was no significant effect oftreatment type
consumed more prey than groups of younger individuals ontheamountofbiomassconsumedinanyoftheanalyses,we
(mean spider instar effect. Table 1), groups consumed more calculated the frequency of sharing separately to determine
preywhenthepreyitemwaslarger(initialpreyweighteffect. whetherkingroupssharedmoreoftenandfoundnoconsistent
TGarebalteer1)parenydboilodmearssspwidaesrsalcsooucldonhsaunmdeldewlharegnermoprreeyspiitdeemsr.s eRffUecta:ndprUeyFsghraroiunpgsotchcaunrriendRnFeaarnldy 2U0U%gmrooruepsf(rFeiqguuernetlyIB)i.n
AULETTA&RAYOR PREYSHARINGNOTPREFERENTIALAMONGKIN 261
—
Table 2. Results of the linear mixed model that excludes all However, ourresultsdo notsupportthishypothesis. Rather,
instancesoflow-duration prey sharing(defined as < 20 min). The ourdata indicate that the overall benefits ofprey sharing to
measuredchangeinspiderweightwasusedastheresponsevariable, youngD.canceridesaresosubstantialthatthebenefitsderived
andtreatmenttype,meanspiderinstar,initialpreyitemweight,and from discriminating preferentially against non-kin in a prey
tmheeacnalicnusltaarteodf“ssphiadreirnsgwimtehtirnict”hewegrreouupseadndasthfeixienditeifalfecwtesi.ghOtnloyftthhee sharingeventtoincreasepotentialinclusivefitnessbenefits is
prey itemwere found to have significant effects on the amount of notproductive.
weightgained by spider groups. Asterisks(***) indicate significant The general benefits ofprey sharing include an increased
P-values. frequencyoffeedingandaccesstolargerpreyitems(Buskirk
1981;Rypstra&Tirey1991;Whitehouse&Lubin2005;Yipet
Factor df F P n al. 2008). Recent field studies have shown that younger D.
Treatment 10 1.57 0.2567 87 cancerides are in better condition when they have older
Meanspiderinstar 78 18.27 <0.0001*** 87 siblings that capture and share larger prey items (E.C. Yip,
Initialpreyweight 77 87.70 <0.0001*** 87 unpubl.data).Additionally,D.cancerideshasanexceptionally
Sharingmetric 78 1.31 0.2560 87 low metabolic rate, resulting in low foraging requirements
(Gilbert et al. unpubl. data): prey sharing with any partners
When we excluded spiders in the RU treatment from the may provide a substantial contribution to their overall
dcoaltlaecatneadlyfsoirs(tohnisthterebaatsmiesntthawtatshetroeolatsimvaelllystmoaldlrsaawmprleeliasbilzee nutAritmioanj.or difference between the two species that might
conclusions)andranthemodelagain,treatmenttypealsohad influence prey-sharing patterns is the extent of their social
asignificanteffect 4.78,« = 127,P= 0.0247,overall behavior: Delena cancerides is a significantly more social
model =0.72),withUFgroupsconsumingmorepreythan species than S. lineatus. Delena cancerides colonies have
RForUUgroups(t = 3.03,df= 13,P = 0.0103). multiplecohortsofsiblingslivingtogetherforapproximately
10-12 mo until individuals reach sexually maturity, after
DISCUSSION which individual females establish their own colonies (L.S.
Spidersthatsharepreywithunrelatedindividualswouldbe Rayor et al, unpubl. data). In contrast, S. lineatus siblings
expectedtoexperiencethesamedirectbenefitsofpreysharing onlylivetogetherfor~30daysbeforedispersing,afterwhich
asthoseindividualsthatsharepreywithgeneticrelativesinthe theylivesolitarily,andindividualfemaleshavesingleclutches
formofdirectconsumptionoffood.However,individualsthat prior to matriphagy (Schneider 1995; Schneider and Lubin
share prey with kin might additionally gain inclusive fitness 1997). Furthermore, although the majority of prey-sharing
benefitssuchastheincreasedproductionofdigestiveenzymes behaviors observed in D. cancerides are between younger
inkingroupssuggestedbySchneiderandBilde(2008).Given individuals(fourth-sixthinstars),individualscontinuetoshare
thatthebiologyofD. canceridesissuchthatthereissomelevel prey throughout their lifetimes (L.S. Rayor unpubl. data),
of interaction between non-kin young in the wild, we whereasS. lineatusfeedcommunallyonlyasjuvenilespriorto
hypothesized that there would be more prey consumed in dispersal (Schneider 1995). There may be greater inclusive
kin-only groups due to greater indirect fitness benefits. fitness pay-offsforsubsocial speciesto discriminate kin than
30
RF RU UF UU RF RU UF UU
5th gth
MeanSpiderInstar Treatment
—
Figure 1. A.Thevariationamongtreatmentgroupsinthemeansharingmetric(=compositemeasureofnumberofindividualssharingand
durationofsharing)observedintrialswherepreywasshared,asafunctionofthemeaninstarofallspidersinthegroup.Whenthespiderswere
younger(fifthinstar),theRFandRUtreatmentgroupssharedmorepreythantheothergroups.Bythesixthinstar,whenindividualsweremore
familiarwitheachotherinalltreatments,sharingdidnotdiffer.B.Thepercentageoftrialsinwhichpreysharingoccurredineachofthefour
treatments.Sharingpatternsareunrelatedtokinorfamiliarity.In50.2%ofalltrials,thepreyitemwasconsumedentirelybyasingleindividual
withoutanysharing.
262 THEJOURNALOFARACHNOLOGY
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recognitioncues.Ouronlyindicationofkinpreferenceisthat Rowell, D.M. & L. Aviles. 1995. Sociality in a bark-dweliing
there was a non-significant trend toward a higher sharing huntsman spider from Australia, Delena cancerides Walckenaer
tmheetrsiicxtahmionnstgarkiwnhdeunritnhgetshpeidfeifrtshwiensrtearm,owrheicfhamdiilsiaaprpweiatrhedobnye Rypg(sArtrorauanp,eafAeo.:rLa.Sgpi&anrgaRsi.snSi.daaTesi)orc.eiyaIl.nsse1pc9it9de1es.r.SPoOrceeicyaoulsxiozge4i,2a:p2r88e67:y-235p0-e2r3.i0s.habilityand
amneocthhaenr.ismFsutfuorrenreesstemaartceh rtehcaotgniitnicoonrpomraaytesheltpheseexplpaoisnsitbhlee Schsnpeiiddeerr,{SJt.eMg.od1y9p9h5u.sSluirnveaitvuasl).aInndsegcrteoswtShociinaugxro4u2p:s23o7f-2a48s.ubsocial
patternsobservedinthepresentstudy. Schneider,J.M.&T.Bilde.2008.Benefitsofcooperationwithgenetic
ACKNOWLEDGMENTS kininasubsocialspider.ProceedingsoftheNationalAcademyof
SciencesUSA 105:10843-10846.
Wethankmembersofthe Rayorlab(“TeamDefena”)for Schneider,J.M.&Y.Lubin. 1997.Doeshighadultmortalityexplain
theirassistanceinthisproject,particularlyChristianHoward, semelparity in the spider Stegodyphus lineatus (Eresidae)? Oikos
Maxine Ames, and Bert Barnes. Leifur Thorbergsson, Max 79:92-100.
Chen, and Francoise Vermeylen of the Cornell Statistical Travers,S.E. 1993.Groupforagingfacilitatesfoodfindinginasemi-
Consulting Unit provided invaluable statistical advice. Eric aquatic hemipteran, Microvelia austrina Bueno (Hemiptera:
eYxipperiamnedntaMlicdheaseilgn.OrFrliesprwoevriedekdindhellypfpurlovifdeeeddbbayckDro.nCotlhee TsoV,elIi.iMda.e)&.PLa.nL-.PaSceivfeircinEgnhtaoumso.lo1g99i8s.tI6n9g:e1s1t7e-d12b!i.omassofpreyasa
Gilbert, Dr. JeffScott, and Cheryl Leichter. The paper was JmoourrenaalccoufrAatreacehsntoilmoagtoyr2o6f:4f0o5rMa0g7in.gintake by spider predators.
improvedbysuggestionsfromLindenHiggins,SimonPollard Whitehouse,M.E.A.&Y.Lubin.2005.Thefunctionsofsocietiesand
andananonymousreviewer. the evolution of group living: spider societies as a test case.
LITERATURECITED BiologicalReviews80:347-361.
Yip,E.C.,S.Clarke&L.S.Rayor.2009.Aliensamongus:nestmate
Aviles, L. 1997. Causes and consequences of cooperation and recognition in the social huntsman spider, Delena cancerides.
SpoecrimaalnenBte-hsaovciioarlitiyniInnssepcitdsersa.ndPp.Ar4a7c6h-nAi9d8s..I(nJ.TCh.eCEhvooelut&ionB.oJ.f YipI,nsEe.cCt.e,sSKo.cSi.auPxow5e6r:s22&3-2L3.1.Aviles. 2008. Cooperativecapture of
BeaCvriess,piA,.Se.d,s.)D..MC.ambRorwiedlgle&UniTv.erEsviatnys.Pre2s0s0,7.CaCmabnrniidbgael,isUmKa.nd kin lParrogceeedpirenygssoolfvetshescNaaltinigonaclhalAlcenagdeemfyaceodf bSyciesnpciedserUSsoAciet1i0e5s:.
recognition in Delenacancerides(Araneae: Sparassidae), asocial 11818-11822.
Bilhdeu,ntTs.m&anYs.pidLeurb.inJ.ou2r0n0a1l.oKfiZnoorleocgoygni2t7i1o:n23a3n-2d37c.annibalism in a Yipd,efEe.nCs.e&aLn.dS.fRoaryaogri.ng20w1i1t.hDouotsoaciva/lesbp?idBeerhsacvoiooprearlatEecionlporgeydaatnodr
Bilsdeu,bsoT.c,iaYl.spLiudebri.n,JoDu.rnaSlmiotfh,EvJo.lMu.tiSocnhanreyidBeirol&ogyA.1A4.:95M9a-k9l6a6.kov. Sociobiologyinpress.
2005.Thetransitiontosocialinbredmatingsystemsinspiders:role ManuscriptreceivedI October2010, revised21 March2011.