Sexual Reproduction in Plants • Movement onto land is an issue Pollination Biology for sexual reproduction in plants - unlike for animals • rely on movement of (1) pollen, (2) young embryo encased in a . real story of the birds & bees . seed (or fruit), or (3) spores and beetles, bugs, butterflies, bats pollination biology seed dispersal Sexual Reproduction in Plants Coevolution Pollination and seed/spore dispersal important Coevolution – interactions between two different clades as aspects of biosystematics in plants: selective forces on each other, resulting in adaptations that • Gene flow increase their interdependency • Outcrossing vs. inbreeding • Reproductive isolation Animal-flowering plant interaction is a classic example of coevolution: • Speciation spore dispersal • Co-speciation (coevolution) pollination biology seed dispersal • Plants evolve elaborate methods to attract animal pollinators • Animals evolve specialized body parts and behaviors that aid plant pollination 1 ! Coevolution109 Coevolution • coevolution with • frequent shifts to different “pollination syndromes” pollinators often leads to from ancestral bee pollination convergence and divergence in flowers • best studied has been the V. Grant B. Grant phlox family: hummingbird Polemoniaceae bat Fig. 1. Floral diversity in Polemoniaceae. (A) Leptosiphon aureus subsp. aureus; (B) Saltugilia splendens subsp. grantii; (C) Navarretia hamata subsp. hamata; (D) Leptosiphon montanus; (E) Phlox divaricata subsp. laphamii; (F) Cantua buxifolia; (G) Aliciellla latifolia subsp. latifolia; (H) Linanthus orcutii; (I) Saltugilia caruifolia; (J) Loeseliastrum schottii; (K) Cobaea scandens; (L) Eriastrum eremicum subsp. eremicum; (M) Navarretia leucocephala; (N) Ipomopsis tenuifolia; (O) Dayia scabra; (P) Gilia leptantha subsp. leptantha. ! 112 Acathogilia Ipomopsis/Bryantiella Aliciella Langloisia Allophyllum Lathrocasis Cantua Leptosiphon Cobaea/Bonplandia Linanthus Collomia Loeselia Dayia Microgilia Eriastrum Navarretia Fouquieria Phlox/Microsteris Gilia Polemonium Giliastrum Saltugilia Gymnosteris • tested with genomic • tested with genomic data (400 nuclear genes) data (400 nuclear genes) ! 109 • bee pollination • bee pollination confirmed as ancestral confirmed as ancestral • a lot of transitions in pollinators! * * Ph.D. Work by Jeff Rose Ph.D. Work by Jeff Rose 70 60 50 40 30 20 10 0 Fig. 4. BEAST maximum clade credibility tree of the phylogenetic history of the polemonioids. Tips are colored by major clade assignment. Asterisks (*) indicate calibration points, light blue bars represent 95% HPD of inferred node ages. Thickened branches indicate posterior probability > 0.90. Fig. 1. Floral diversity in Polemoniaceae. (A) Leptosiphon aureus subsp. aureus; (B) Saltugilia 2 splendens subsp. grantii; (C) Navarretia hamata subsp. hamata; (D) Leptosiphon montanus; (E) Phlox divaricata subsp. laphamii; (F) Cantua buxifolia; (G) Aliciellla latifolia subsp. latifolia; (H) Linanthus orcutii; (I) Saltugilia caruifolia; (J) Loeseliastrum schottii; (K) Cobaea scandens; (L) Eriastrum eremicum subsp. eremicum; (M) Navarretia leucocephala; (N) Ipomopsis tenuifolia; (O) Dayia scabra; (P) Gilia leptantha subsp. leptantha. What is Pollination? Evolution of the Flower • Pollination: The transfer of pollen from the male anther to the Evolution of the flower is linked with evolution of female stigma, in same plant or between two plants pollination syndromes and why divergence/convergence is pervasive in floral features • bisexual flowers to bring male and female parts closer • primitive flowers had separate pollen- and carpel-bearing structures such as in Archaefructus (and in all gymnosperms) Archaefructus Evolution of the Flower Evolution of the Flower • closed carpel for protection of • fusion of carpels into one pistil - ovules and seeds efficient deposition of pollen and movement of pollen tubes down one or few style lobes Drimys - basal angiosperm 3 Evolution of the Flower Evolution of the Flower • epigyny - protection of • fusion of floral parts - • exotic landing platforms, spurs, nectaries, etc - ovules from probing animals tubular structures for specialization for specific pollinators restricting nectar access Evolution of the Flower Evolution of the Flower Placement of both stamens and carpels in the same flower Placement of both stamens and carpels in the same flower causes inbreeding - subsequent selection for outcrossing causes inbreeding - subsequent selection for outcrossing • protogyny or protandry - temporal sequence of anthesis • self incompatibility - chemical on surface of pollen and or stigma receptivity stigma/style that prevent pollen tube germination on the same flower (S allele incompatibility system) 1. female phase 2. male phase Protogyny in Asimina - pawpaw (Annonaceae) 4 Evolution of the Flower Pollination Syndromes Placement of both stamens and carpels in the same flower • morphologically convergent adaptive trends exhibited by causes inbreeding - subsequent selection for outcrossing the floral features of pollinated plants and, in animal pollination, the mouthpart structure and other flower- • heterostyly - reciprocal interactive features of the pollinators separation of anthers & stigmas Passive Active 1. Wind - anemophily 3. Animal - zoophily • unisexuality - reversal 2. Water - hydrophily (ornithophily, entomophily) back to separate sexes in flowers Primula - primrose Cucurbita - zucchini Insect Pollination - Entomophily ANA Pollination Modern insect pollinators • Beetles -- Coleoptera • Flies -- Diptera • Ants -- Hymenoptera • Butterflies -- Lepidoptera • Moths -- Lepidoptera • Bees -- Hymenoptera American Journal of Botany Primitive type of insect pollination appears to be beetle or January 2009 fly pollination ANA grade has surprising number of . including thermophily (heat to pollination types . volatize scents for fly pollination) in Illicium floridanum 5 Beetle Pollination Beetle Pollination • likely that beetles first visited the female • beetle flowers usually cones of conifers and fed on the pollination have numerous parts - droplet exudates flowers provide stamens, petals as food for chewing • function of pollination droplet originally beetles for capture of wind-blown pollen — shift as food attractant for beetles as in Welwitschia Nuphar - yellow water lily Welwitschia longitudinal view of beetle flowers illustrating various methods of protecting pistils Beetle Pollination Beetle Pollination • beetle flowers are pale or dull in color, but • carrion beetle pollination is more advanced - coprophily with strong odor • flowers have spicy, Araceae fruity, or rotten smell attracting beetles Nuphar - yellow water lily Hydnora africana Cyclocephala beetles 6 Fly Pollination Fly Pollination • carrion/dung flies have special pollination system (sapromyophily) • two specialist families - Aristolochiaceae (birthwort) and Araceae with no reward - flies attracted to flowers to lay eggs (arum) • flowers brownish/purple, often mottled, with foetid odor Aristolochia species Asarum canadense - wild ginger (Aristolochiaceae) Fly Pollination Fly Pollination • two specialist families - Aristolochiaceae (birthwort) and Araceae • two specialist families - Aristolochiaceae (birthwort) and Araceae (arum) (arum) Jack-in-the-pulpit Skunk cabbage Dragon-root Amorphophallus titanum - titan arum 7 Fly Pollination Fly Pollination • many parasites and saprotrophs utilize carrion flies • advanced fly pollination can be similar to bee pollination - ecologically similar (“bee flies”) Syrphid on Anemone Xanthogramma on morning glory Rafflesia (Rafflesiaceae) Burmanniaceae Heliosis (Balanophoraceae) Bee & Wasp Pollination Bee & Wasp Pollination • most important group of flower pollinators • flowers are white, blue, yellow - generally not red • attracted to flower mainly for food (pollen, nectar, oils, etc.) Andrena after pollen Halictid after nectar Macropis europea on Lysimachia vulgaris • oil is essential for juvenile development 8 Bee & Wasp Pollination Bee & Wasp Pollination • flowers are white, blue, yellow - generally not red • flowers are white, blue, yellow - generally not red • strong UV light patterns • strong UV light patterns • “nectar guides” • “nectar guides” • fragrant (perfumes, pheromones) • poricidal anthers - buzz pollination Eulaema (euglossine) Solanum - Solanaceae Perfume industry Bee & Wasp Pollination Bee & Wasp Pollination • flowers are white, blue, yellow - generally not red • Some plants take advantage of the sex drive of certain • strong UV light patterns insects • “nectar guides” • fragrant (perfumes, pheromones) • Mirror or bee mimic orchids - pheromones • poricidal anthers - buzz pollination • Male insect mates with flowers • zygomorphic often - landing platform • Orchid pollinated Ophrys ciliatum - orchid in the Mediterranean pollinated by wasp – mint Calceolaria Ophrys Scolia ciliata Ophrys 9 Bee & Wasp Pollination Catasetum Pollination • exotic type of euglossine (Eulaema, Euglossa) bee pollination Two European bee mimic orchids • Catasetum orchid flowers unisexual and strongly dimorphic pollinated by different species of bees • why this strong dimorphism? • why do males of different species of Catasetum appear more different than do the females? Ophrys lutea Ophrys sicula What pollinates this tiger orchid from Colombia? Mrs. Santa Claus? Catasetum Pollination Catasetum Pollination • male euglossines collect pheromones from flowers • pollination biology drives sexual dimorphism and male-male • male Catasetum flowers discharge pollinia