Transcript animals
origin of flowers and fruits • • • • angiosperms (seeds inside fruits fruits develop from flowers at least 140 my ago coevolution w/animals--> diversification • animal pollination & seed dispersal • agriculture model organism for research Arabidopsis • small genome (sequenced) • fast lifecycle (genetics) • small size (fits in small space) flower • • • • shoot modified for reproduction parts are modified leaves sepals protect petals attract pollinators • stamens have pollen • carpels have ovules fruit • ovules inside ovary • ovary develops into fruit • fruit is mature ovary with seeds • fruit attracts seed dispersers angiosperm life cycle • further reduction in gametophyte – no antheridia OR ARCHEGONIA • • • • sperm + egg = zygote AND extra sperm fuses with 2 other nuclei makes stored food: endosperm (3n) food-->cotyledons, or not (eg corn) angiosperm seed •seed coat (2n) endosperm (3n) embryo (2n) embryo is new sporophyte endosperm is stored food gymnosperms • • • • • • • angiosperms pollen grains ovules seeds (w/stored food) food is megagphyte food is endosperm food always made food only if fertilized cones flowers seeds on scale seeds in fruit types of flower • flowers solitary or in cluster = inflorescence • grasses infls. have tiny flowers, wind pollination – corn: many stigmas (silks), one /flower, each kernel is fruit • examples of inflorescences: • 1) catkin = dangling infl. (eg. oak) – tiny flowers, wind pollination • 2) composite “flower” = infl. – (eg sunflower) big, attract pollinator – each flower has own carpel (& fruit) flowers & pollinators • some flowers attract many pollinators • bees are generalists--pollinate diverse plants • showy (esp red) flowers w/ nectar, NOT fragrant-- birds • colorless, fragrant flowers-beetles, nocturnal moths, bats flowers & pollinators • • • • • • • smell & look like dead meat-- flies eg Titan arum—giant stinky infl. fly pollination male flowers (top) female flowers w/fly larvae bird-dispersed fruits Thermal Images of Titan heat mimics rotting carcass, disperses smell QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. images by Frank Landis http://www.news.wisc.edu/titanarum/facts.html co-evolution: orchids • flower shapes accomodate certain insects • Madagascar orchid, 30 cm tube • Darwin predicted pollinator • hawkmoth discovered seed dispersal • wind: orchids, dandelion, maple • animals • nutritious fruits w/changes in color, sweetness • burrs (plant velcro) coffee