Transcript Flowers
Reproduction and attracting mates: Flowers (including zygomorphy, pollination, flowering time) Questions • Discussions: – Maria M: posting paper and questions for this week – Jon: will be picking a paper to post for next week – Peter Stevens is taking students around Orchid house at gardens at 10 am probably on Saturday. Let him or me know if you are interested. • Any questions? What’s a flower? What’s it for? Ferns Gymnosperms Angiosperms Flower evolution • 130-250 mya – Modified leaves (why?) What’s a flower? What’s it for? • Reproductive structure of angiosperms: – Heterosporangiate typically consisting of androecium, gynoecium, usually surrounded by a perianth and borne on an axis or receptacle Flower morphology • Pedicel • Flower parts in whorls: (4,5’s or 3’s) – Calyx (sepals), Corolla (petals), Androecium (stamens with anther, filament), Gynoecium (pistils with stigma, style, ovary) Symmetry • Actinomorphic (radially symmetric) vs zygomorphic (1 bisecting line of symmetry) • Asymmetric: uncommon (Cannanceae, Marantaceae) Flower vs. Inflorescence Cercidiphyllum Breeding systems: outcrossing and inbreeding • Spatial: – Flower: perfect (both sexes) vs. imperfect (1 sex) – Plant: monoecious (1 sex) vs. dioecious (both sexes) – Heterostyly Breeding systems: outcrossing and inbreeding • Temporal: Dichogamy – Protandry: stamens before carpels – Protogyny: carpels before stamens Pollination syndromes • Animal: Insects, birds, bats – Rewards: Nectar, pollen, fragrance, oils – Attract pollinators: Scent, color patterning, mimicry (Orchidceae) • Abiotic: Wind and water • Self pollinated, Cleistogamous Evolution of oil production and collection • Renner and Schaefer. 2010. Phil. Trans. R. Soc. B. 365:423-435. – Bees collect oil for larvae and pollinate flowers – Question: When and how often oil-offering flowers and oil-foraging bees evolved? Oil and bees • Renner and Schaefer. 2010. Phil. Trans. R. Soc. B. 365:423-435. – Question: When and how often oil-offering flowers and oil-foraging bees evolved? • Oil flowers evolved at least 28 times and lost 36-40 times. Oldest just after the K/T boundary65 mya in America (Melpighiaceae) and Africa (Curcurbitaceae, and Laurasia (Myrsinaceae) taxa • Bees evolved oil foraging at least 7 times with earliest at least 53-56 Mya (but probably older) Phylogenies Build ups Evolution of floral morphology Evolution of floral morphology Question • Is flower symmetry associated with changes in speciation rates mediated via pollinators? Question • Is flower symmetry associated with changes in speciation rates mediated via pollinators? – Suggest bilaterally symmetrical flowers can restrict pollinator access to flowers, direct pollen placement, and lead to greater reproductive isolation – Predict that bilaterally symmetrical flowers have higher speciation rates than radially symmetrical flowers Question • Is flower symmetry associated with changes in speciation rates mediated via pollinators? – Corolla symmetry data for animal pollinated families from the literature – Sister-group comparisons (40 zygomorphic clades and 19 comparisons) • Building an angiosperm tree and mapping on zygomorphy • Looking for the actinomorphic sister • Getting number of species in family from literature Evolution of floral morphology Zygo-Actino species * = Actino † = Zygo Question • Is flower symmetry associated with changes in speciation rates mediated via pollinators? – In 15/19 comparisons zygomorphic clade was more diverse than actinomorphic clade