Pollination Biology. . . real story of the birds & bees . . .and beetles, bugs, butterflies, batsSexual Reproduction in Plants• Movement onto land is an issuefor sexual reproduction in plants -unlike for animals• rely on movement of (1) pollenand (2) young embryo encased in aseed (or fruit)pollination biologyseed dispersalSexual Reproduction in Plants• Gene flow• Outcrossing vs. inbreeding• Reproductive isolation• Speciation• Co-speciation (coevolution)Pollination and seed dispersal important aspects ofbiosystematics in plants:pollination biologyseed dispersalCoevolution – interactions between two different clades asselective forces on each other, resulting in adaptations thatincrease their interdependencyCoevolutionAnimal-flowering plant interaction isa classic example of coevolution:• Plants evolve elaborate methods toattract animal pollinators• Animals evolve specialized bodyparts and behaviors that aid plantpollinationDivergence vs. Convergence• the dual issue of divergence of closely related taxa, andconvergence of distantly related taxa, is important inbiosystematic studies of seed dispersal and pollination biologyZjhra, Olmstead, Sytsma 2004Divergence vs. Convergence• classic example of both divergence and convergence inpollination is the family Polemoniaceaehummingbirdbat• frequent shifts to different “pollinationsyndromes” from ancestral bee pollinationV. GrantDivergence vs. Convergence• neater example is evolution of orchid floral form in Platantheraof Northern Hemisphere - read Hapeman & Inoue paper!Platanthera leucophaeaPrairie-fringed orchidDivergence vs. Convergence• DNA relationships indicate remarkable divergent and convergentshifts - what kinds of floral changes have been involved with 3separate shifts to nocturnal hawkmoth pollination?Platanthera leucophaeaPrairie-fringed orchidMullerian & Batesian Convergence• interesting example of convergence in pollination amongthree genera of unrelated families in American tropics• orange and yellow pigments used asanimal signallingPeruvian assassin bug• coloration pattern used by unrelated, nectar-bearing genera to attract butterflies and beesAsclepias - milkweed Lantana - sage• Mullerian mimicry - reinforcing signalMullerian & Batesian Convergence• interesting example of convergence in pollination amongthree genera of unrelated families in American tropics• a third genus shares the pollination signalbut offers no nectar rewardPeruvian assassin bugAsclepias - milkweed Lantana - sage• Batesian mimicry - exploiting the signalEpidendrum - orchidSeed vs. Pollen Dispersal• Seed dispersal more important in field of plant geography -the study of distributions of plant taxaWhat is Pollination?• Pollination: The transfer of pollen from the male anther to thefemale stigma, in same plant or between two plantsPollination Syndromes• morphologically convergent adaptive trends exhibited bythe floral features of pollinated plants and, in animalpollination, the mouthpart structure and other flower-interactive features of the pollinators1. Wind - anemophily3. Animal - zoophily(ornithophily, entomophily)Passive Active2. Water - hydrophilyWhy do Animals Pollinate Plants?• Food reward - in exchange for movingtheir pollen to another flower• Nectar – a sugary solution producedin special flower glands called nectaries– Nectar concentration matches energyrequirements of the pollinator: bird- and bee-pollinated flowers have different sugar conc.• Pollen – is high in protein, some beesand beetles eat it– Flowers sometimes produce two kinds ofpollen: a normal and a sterile, but tasty, kind,for the insectEvolution of the FlowerEvolution of the flower is linked with evolution ofpollination syndromes and why divergence/convergence ispervasive in floral features• bisexual flowers to bring maleand female parts closer• primitive flowers had separatepollen- and carpel-bearingstructures such as in Archaefructus(and in all gymnosperms)ArchaefructusEvolution of the Flower• closed carpel for protection ofovules and seedsDrimys - basal angiospermEvolution of the Flower• fusion of carpels into one pistil -efficient deposition of pollen andmovement of pollen tubes downone or few style lobesEvolution of the Flower• epigyny - protection ofovules from probing animals• fusion of floral parts -tubular structures forrestricting nectar accessEvolution of the Flower• exotic landing platforms, spurs, nectaries, etc -specialization for specific pollinatorsEvolution of the FlowerPlacement of both stamens and carpels in the same flowercauses inbreeding - subsequent selection for outcrossing• protogyny or protandry - temporal sequence of anthesisor stigma receptivity1. female phase 2. male phaseProtogyny in Asimina - pawpaw (Annonaceae)Evolution of the FlowerPlacement of both stamens and carpels in the same flowercauses inbreeding - subsequent selection for outcrossing• self incompatibility - chemical on surface of pollen andstigma/style that prevent pollen tube germinationon the same flower (S allele incompatibility system)Evolution of the FlowerPlacement of both stamens and carpels in the same flowercauses inbreeding - subsequent selection for outcrossing• heterostyly - reciprocalseparation of anthers &stigmasPrimula - primrose• unisexuality - reversalback to separate sexes inflowersCucurbita - zucchiniPollination Syndromes - Caveats• not all visitors are pollinators“robber” lycaenid on Lotus“robber” hummingbird on CampsisPollination Syndromes - Caveats• many plant species with aspecific “syndrome” have asurprising “suite” of effectivepollinatorsSunbird on bee-pollinatedAsclepiasHalictid bee and vespid wasp pollinating moth-pollinated Silene vulgarisPollination Syndromes - Caveats• insect lineages diversified prior to angiosperms, but co-opted by and responded to by angiospermsInsect Pollination - EntomophilyModern insect pollinators• Beetles -- Coleoptera• Flies -- Diptera• Ants -- Hymenoptera• Butterflies -- Lepidoptera• Moths -- Lepidoptera• Bees -- HymenopteraPrimitive type of insect pollination appears to be beetle orfly pollinationANITA PollinationANITA grade has surprising number ofpollination types . . .. . . including thermophily (heat tovolatize scents for fly pollination)in Illicium floridanumAmerican Journal of BotanyJanuary 2009Beetle Pollination• likely that beetle first visited the femalecones of conifers and fed on the