Zol415, 2004, NatalieDuboisTalk1Opportunities for polygyny and reproductive investment in house wrensNatalie S. DuboisDepartments of Zoology &Ecology, Evolutionary Biology and BehaviorKellogg Biological StationMichigan State UniversityJ.J. AudubonInvestment in reproductionBenefitsdecreased future reproduction or survivalgameteseggsyoungCostsincreased fitness from current attemptAn individual’s fitness depends on both the number and quality of offspring it is able to produce over its lifetimeINVESTMENT INCURRENT REPRODUCTIONINVESTMENT INFUTURE REPRODUCTIONOR SURVIVALTRADE-OFFFemale collared flycatchers with experimentally enlarged broodslay smaller clutches later in lifeGustafsson & Pärt 1990Clutch sizeenlargedcontrolGustafsson, L., and T. Pärt. 1990. Nature 347:279-281.Experimentally removing second broods increases survival and fecunditythe following year in female great titsVerhulst 1998Verhulst, S. 1998. Functional Ecology 12:132-140.ControlRemovedManipulation second clutchNo. of fledglings next year02468SurvivalManipulation of second clutchControl Removed00.40.8Zol415, 2004, NatalieDuboisTalk2Under this trade-off we would expect increased opportunities for additional matings to result in decreased investment in the current reproductive attemptFor polygamous or multi-brooded species, future costs can be almost immediate if investment in the current reproductive attempt decreases opportunities for additional matingsInvestment in reproductionBenefitsCostsINVESTMENT INCURRENT REPRODUCTIONINVESTMENT INFUTURE REPRODUCTIONOR SURVIVALTRADE-OFFmate attraction opportunitySmith, H. G. 1995. Proceedings of the Royal Society of London Series B 260:45-51.male proportion of incubation00.20.4single boxdoubleboxproportion of time male sang during incubation period00.20.1single boxdoubleboxMale European starlings with a surplus cavity added to their territories contributed less parental care but increased mate attraction effortsSmith 1995investment incurrent reproductioninvestment in future reproductionTRADE-OFFPrevious studies have manipulated female investment in current reproduction and demonstrated trade-offs between current and future reproduction……ignoring effects of mate choice and paternal investment on female investmentinvestment incurrent reproductioninvestment in future reproductionTRADE-OFFmate attraction opportunityAnd shown that male trade-offs between current and future reproduction can be mediated by mate attraction opportunity……ignoring effects on female investment in reproductionZol415, 2004, NatalieDuboisTalk3investment incurrent reproductioninvestment in future reproductionTRADE-OFFmate attraction opportunityfemale investment in reproductionMALESFEMALESHow do opportunities for polygyny affect1. male investment in current and future reproduction?2. female mate choice and investment in reproduction?Field Guide to the Birds of North America (1994)HOUSE WRENSNorth American distributionBREEDING SEASONEND APRIL males returnestablish breeding territoriesstart building nestsHOUSE WRENS2° cavitynestersfacultativelypolygynoussong to attract matesfemales returnprospect among malesexamine nest siteschoose matecomplete nestMAY line nestlay clutch (5-7 eggs)incubatematernal investmentboth parents provision youngparental investmentJUNE young fledgesecond broodAUGUST end of breeding seasonZol415, 2004, NatalieDuboisTalk4Manipulating availability of surplus cavitiespre-arrivalmale arrivalfirst broods1B3BPre-pairing treatmentrandomizeavailable nest box1Bplugged nest boxesstart of incubationlaying periodFEMALE MATE CHOICEREPRO. INVESTMENTfemale arrivalAPRIL AUGincubation and nestling periodsMALE TRADEOFFSCURRENT VS FUTURE1B3BPost-laying treatmentre-randomizesecond broodsMALE INVESTMENTFEMALE INVESTMENT1B3BPost-laying treatmentre-randomizePre-pairing treatment1B3BHow do opportunities for polygyny affect1. male investment in current and future reproduction?2. female mate choice and investment in reproduction?Conceptual framework: male trade-offs between current and future reproductionAvailability of surplus cavities affects male opportunity to acquire additional matesPolygyny increases male reproductive successMale parental care affects reproductive successINVESTMENT INCURRENT REPRODUCTIONINVESTMENT INFUTURE REPRODUCTIONZol415, 2004, NatalieDuboisTalk5Conceptual framework: male trade-offs between current and future reproductionFew opportunities foradditional matingsMate attractionParental careINVESTMENT INCURRENT REPRODUCTIONINVESTMENT INFUTURE REPRODUCTIONConceptual framework: male trade-offs between current and future reproductionMany opportunities for additional matingsMate attractionParental careINVESTMENT INCURRENT REPRODUCTIONINVESTMENT INFUTURE REPRODUCTIONMate attractionParental careINVESTMENT INCURRENT REPRODUCTIONINVESTMENT INFUTURE REPRODUCTIONAvailability of surplus cavities affects male opportunity to acquire additional matesRecorded male song for 30 minutes during incubation and nestling periodsObserved paternal provisioning rates during nestling periodPredictions: Male provisioning and mate attractionDuring first broods, males with access to surplus cavities willincrease mate attraction effort and provision at lower rates relative to males with access to single cavitiessurplus singleMale provisioning rateMate attraction effortsurplus singleEarly season nestsZol415, 2004, NatalieDuboisTalk600.10.20.30.40.5IncubationPeriodNestling Periodmean ± seSong rate indexsurplussingleMale song rates (early season nests only)Males with surplus cavities in their territories sang morethan males with single cavities in their territories.Post-laying treatment P < 0.03Time × treatment P < 0.0800.514812Proportion of males provisioning nestlingsBrood dayMale provisioning rates (early season nests only)There were no differences in the proportion of males provisioningnestlings between males with surplus cavities and single cavities in their territories.surplussingle1.522.54812Male provisioning trips per nestlingBrood daymean ± seMale provisioning rates (early season nests only)Of males that provisioned, there were no differences in provisioning ratesbetween males with surplus cavities and single cavities in their territories.surplussingleTrade-offs might occur earlier in the nestling periodMale removal studies show that paternal care is most critical when females are brooding young and removal after that period has little effect on reproductive success (Johnson et al. 1992,