Reproductive BehaviorSlide 2Having a Y ChromosomeDefinitions of Male & FemaleBiological DefinitionAnisogamySlide 7Slide 8Reproduction is an energy investmentConsequencesBateman’s PrincipleRobert TriversTerminologyConsequence of AnisogamySex ConflictEffectsIsogamous SpeciesAnisogamous SpeciesSexual DimorphismSexual Dimorphism- colorSexual Dimorphism- SizeSex (Intralocus) ConflictSex ChromosomesSlide 24Interlocus Conflict Mating RateFun with fruit fliesBateman’s ExperimentDrosophila melanogasterSlide 29Darwin & EvolutionHmm what’s that about…Darwin on Sex…Slide 33He also noticed that ….And that…Darwin’s Theory of Sexual SelectionSexual Selection vs Natural SelectionSexual Selection Works 2 WaysIntrasexual SelectionSlide 40Slide 41Intersexual SelectionFemale ChoiceMarion Petrie & the Blasted PeacockSlide 45Slide 46Slide 47Slide 48Slide 49Slide 50Slide 51Intrasexual CompetitionMales Short & SweetSlide 54Males Win Big, Lose BigMales Are RiskierSlide 57Slide 58Slide 59Male Survivorship Low Relative to FemalesSoay RamsLow Male SurvivorshipShort Lifespan Influences Reproductive EffortMale-Male CompetitionFinding Potential PartnersMoths as ScramblersAaah.. the better to find youIndian Moon MothEndurance RivalryAntechinus spContests CompetitionCombat ContestsElephant sealCombat ConsequencesSex on the beachStrength Signal ContestsAlternative ContestsSneaker3 color MorphsBluegill SunfishDense ColoniesMales Establish TerritoryMales Build & Guard NestsMating PairSlide 85Parental MaleSatellite MaleParental Male- Female- SatelliteSneaker MaleGame TheoryContest ResultsHermaphroditesHermaphrodite as a lifestyleLeopard SlugProtandry Sex ChangeDwarf MalesSlide 97Low DensityForced CopulationInfanticideSlide 101Costs of InfanticideCounter adaptations of InfanticidePromiscuitySperm CompetitionParker’s Observations2 General categories of Sperm CompetitionMate GuardingMate guarding strategiesMate Guarding- Prolonged CopulationChemical Mate GuardingMating PlugsSlide 113Fly with no common nameDisplace Rival SpermBlack-winged DamselflySlide 117Sperm MotilitySperm AggregationsSperm ProfligacyMaryland Blue CrabsPerceived CompetitionMeadow VoleBarbary MacaqueReproductive BehaviorHaving a Y ChromosomeDefinitions of Male & Female•Gender is a social categorization•Biological categories have to apply to all forms of life–Algae, humans, sea stars, plantsBiological Definition•Based on gamete size•Male–Small gametes–Sperm (spermatozoa)•Female–Large gametes–Egg (oocyte)Anisogamy•“not same gametes”•Gametes different size•Usually 2 sizes- small & large•Rarely some species have multiple sized gametes–Chlamydomonas euchlora–Divides 4-64 times any inbetween•4 = big gametes•64 = small gametesAnisogamyReproduction is an energy investment•Different strategies exist for reproductive investment•Trade-off exists between –size & number of gametes•Lot of small–Size & quality of gametes•Few high quality–Results in a selection force for 2 fertility strategiesConsequences•Males –Lots of gametes–Little energy per gamete produced–Evolution favors mechanisms for encountering female–Adaptations•Motile•Locate- egg tracking systems•Females–Fewer gametes–Lots energy per gamete produced–Evolution favors mechanisms for being encountered–Adaptations•Chemical attractants•SelectionBateman’s Principle•Bateman 1948•The sex which invests the most in producing offspring becomes a limiting resource over which the other sex will compete–Male strategy–Female strategy–Males should be eager, females…“The female, with the rarest exceptions, is less eager than the male…she is coy,And may often be seen endeavoring for a long time to escape.”Robert Trivers•1972•Expanded Bateman’s principle to extend beyond gamete scope to include all aspects of reproductive effort–Gestation, feeding, protection•The sex that invests more should be passive & discriminatingTerminology•Reproductive effort–Proportion of the total energy budget of an organism that is devoted to reproduction•Parental Investment (effort)–Any investment made by parent to individual offspring to increase the survivability of the offspring•Mating effort–Any investment made in by individual to increase reproductive eventConsequence of Anisogamy•Male–Increased proportion of reproductive effort directed into mating effort•Female–Increased proportion of reproductive effort directed into Parental effortSex Conflict•Conflict of interest as two sexes reproductive strategies change over the course of evolution•Ex sponges sex strategies similar among sexes•Vs Peacock & peahenEffects •Results in morphological differences•Results in behavioral differencesIsogamous SpeciesAnisogamous SpeciesSexual Dimorphism•Differences between individuals of different sex in the same species–Color–Size–Reproductive structuresSexual Dimorphism- colorSexual Dimorphism- SizeSex (Intralocus) Conflict•Selection favors long tail in male–Result of female preference•Selection favors intermediate tail length in female–Maximize flight•Selection forces different in sexesSex Chromosomes•X & Y chromosomes share many genes, but Y chromosomes has regions of genes not found on X Chromosome–Ex. SRY genes •Homology of gene sequences suggest shared ancestryInterlocus ConflictMating Rate•Male increases fitness by reproducing more often–Frequent copulation–Large number of sperm–Higher likelihood of dying young •Female increases fitness by producing fewer gametes over longer period of time–Eggs are expensive–Producing fewer per reproductive event puts less energetic toll on female–Greater likelihood of surviving for a next reproductive eventFun with fruit fliesBateman’s Experiment •Mated drosophila•Males mated with several females produced 3-4X offspring produced by monogamous flies •Females less than 2X as many offspring when mated with multiple malesDrosophila melanogaster•Male semen has spermicide protein to kill rival sperm•Toxic to femaleDrosophila melanogaster•Male semen has components that–stimulate the female to increase the rate of egg laying–Reduces her desire to mate with other males•Cost to female is reduced lifespanDarwin & Evolution•Evolution by natural selection–Struggle for existence•Adaptations increase individual survivalThe sight of a feather in a peacock’s feather, whenever I gaze at it, makes me sickHmm