lecture 23 - flower evolution

Question 1

Darwin’s abominable mystery

Answer 1

evolution via NS couldn’t explain the rapid evolution of angiosperm lineage

Question 2

bennettitales

Answer 2

extinct fossil seed plant group
~225 MYA
intermediate between gymnosperms and angiosperms
ovules were in a cupule, precursor to flowers in angiosperms?

Question 3

caytonia

Answer 3

extinct plant, ~200-15 MYA
intermediate between gymnos and angios
produced pollen in microsporangia that resembled anthers
ovules were surrounded by a cupule

Question 4

magnoliid hypothesis:

Answer 4

ancestors of angiosperms were woody plants with a symmetrical flower type with many unfused parts

Question 5

paleoherb hypothesis

Answer 5

angiosperm ancestors were tropical and herbaceous, with small flowers containing few parts

Question 6

flowers generally have 4 organ types:

Answer 6

sepals, petals, stamens, carpels

Question 7

how do flowers develop on a plant from vegetative growth?

Answer 7

shoot meristem must be induced to become reproductive, produce a floral shoot

Question 8

flower organs are modified ___

Answer 8

leaves

Question 9

LEAFY gene

Answer 9

master regulator (transcription factor) that turns on a cascade of other gene regulators, switches vegetative growth to floral growth, is responsible for the development of specific floral organs

Question 10

MADS box genes

Answer 10

separate set of regulator proteins that interact to allow development of florwer

Question 11

whorls of cells in floral meristem correspond to:

Answer 11

whorls of organs in flower

Question 12

ABC model

always beautiful
first!
big cock
c for c

Answer 12

interacting parts of the genome which code for specific organs in the flower

B
A C

A+B = petals
A=sepals
B+C = stamen
c = carpels

Question 13

3 different regions/groups of genes involved in flower production (+ 1 for extra!)

Answer 13

MADS box genes
ABC(DE) genes
LEAFY genes
MIKC precursor to MADS box genes (gave rise to ABC)