Lecture 13 Plant 5: Angiosperms

Question 1

Advantages of wood, pollen & seeds (5)

Answer 1

• Plants can get bigger
• No longer required water to reproduce
• Gametophyte now totally protected by adult sporophyte
• More varied dispersal of male gametes (via pollen)
• Better dispersal of sexual offspring (seeds)

Question 2

3 key innovations of angiosperms

Answer 2

Flowers, fruits, better xylem

Question 3

Number of species of angiosperms and its ranking

Answer 3

300,000; second to beetles

Question 4

What is adaptive radiation is

Answer 4

when one lineage produces an unusually large number of descendant species adapted to many habitats/ecological niches (ex. angiosperms)

Question 5

Connection between angiosperms’ innovation and their radiation

Answer 5

Enable angiosperms to transport water (efficient xylem), pollen (flowers), & seeds (fruits) efficiently

Question 6

The last and hardest step of speciation is

Answer 6

reproductive isolation (diverging species no
longer interbreed)

Question 7

Why angiosperms’ flowers aid in reproductive isolation

Answer 7

• Flowers directly involved in mating & mate-choice
• Divergence in flowers can more quickly lead to reproductive isolation

Question 8

Introduce flowers’ parts and their functions (5)

Answer 8

• Flowers are for plant sex, especially for finding mates
• Contain the reproductive organs: female parts (carpel), male parts (stamen), or both
• ♀: ovules develop in the ovary
• ♂: pollen grains develop in the anther
• Later, plants enclosed carpels & stamens in petals which evolved from leaves

They diversify (because) and so does the sizes, shapes, & colours

Question 9

Pollination is

Answer 9

pollen transfer from anther to compatible, receptive stigma. Pollen that lands on wrong stigma (or anywhere else) is wasted

Question 10

Outcross pollination is

Answer 10

pollen & stigma on different plant

Question 11

Adaptations for chances of pollen getting to right stigma (7)

Answer 11

• ~80% of angiosperms use animal pollinators

Almost any floral trait can affect pollination, including: Colour, Scent (both sweet and putrid), Shape, Markings (including UV-visible), Position, Pollinator rewards (nectar, oils, heat), Flowering time (day, night, season)

Question 12

Adaptive significance of floral traits (3)

Answer 12

Floral traits can:
* attract good pollinators
* deter non-pollinating visitors
* manipulate visitor behaviour to maximize pollen transfer

Question 13

Significance of pollination shifts for angiosperms (4)

Answer 13

• Pollination definitely involved in speciation of lineages with complex flowers
• Pollinator shifts can be 1st step in reproductive isolation
• Simple changes in flowers (eg colour, nectar spur length, flowering time) can lead to
  pollinator shifts
• Experimental crosses & genetic analyses show large changes in flower morphology
  possible with single mutations

Question 14

Innovation of fruits (6)

Answer 14

• Unlike gymnosperms, angiosperm ovules develop in an ovary
• Ovule (includes integument -> seed coat)
• Ovary (additional maternal tissue around ovule)
• After fertilization (usually) ovary tissue ripens -> fruit
• Most seed-dispersal structures develop from ovary wall (pericarp) and/or ovary tissue
• General functions: protect developing seed, seed dispersal

Question 15

Other fruits’ seed dispersal rather than to be eaten (4)

Answer 15

• Wind
• Animal fur
• Explosion (‘ballistic seed dispersal’)
• Water

Question 16

Introduce seed dispersal - to be eaten by animals

Answer 16

• seeds pass through gut and get pooped out later in new place or hidden and forgotten! Eg. Squirrels/acorns

Question 17

In what aspects fruits allow greater variety and specificity of dispersal (3)

Answer 17

Different distances, physical conditions, to different habitats

Question 18

Two major groups of angiosperms

Answer 18

1. Monocotyledons (monocots)
2. Dicotyledons (dicots)

Their differences are cotelydons, vascular tissues, leaf veins.

Question 19

Examples of monocots and dicots

Answer 19

• All grasses (includes grains on which agricultural civilizations are built) are monocots
• Irises, orchids, lilies, palms
• Have lost some features (like woodiness)

Dicots are everything else including major food crops like beans, soy.

Question 20

Phylogeny for monocots and dicots (2)

Answer 20

• Monocots monophyletic
• Dicots now known to be paraphyletic
  (i.e. monocots evolved from dicots)

Question 21

Angiosperm as an example of modularity (4)

Answer 21

• Plants produce multiples of most morphological structures, that can take each other’s place
• Can create vastly different structures with the same tissue or analogous structures via different pathways/tissues
• Especially notable in angiosperms
• Allows huge flexibility for individuals & evolutionary lineages

Question 22

Describe phylogeny of all plants

Answer 22