L8 and 9 Karin Kjernsmo - Pollination, fruits and seeds Flashcards
Allogamy
Cross pollination, from flowers with different genetic constitutions
Autogamy
Self pollination, same genetic constitution.
Anemophily
Wind pollination
What characteristics do wind pollinated plants have?
small flowers grouped together
produce a lot of pollen, as not always very efficient.
what type of pollination do 87% of plants undergo?
Animal pollination
Mutualism, so costs are involved too
Co evolution of flowers and pollinators
How do plants compete with each other for pollinators?
much competition for cross pollination, need to attract polltinators and ensure they remember the specific plant in order to return. use colour and UV guides to attract. Nectar guides Conical cells Irridescence
What pigments make colour in flowers?
Carotenoids - absorb blue, reflect yellow - red, rich orange colour
Bilirubin - deep purple/blue colours, when chlorophyll is broken down
Flavenoids - flavenols and anthrocyanin, magenta violet colours
Betalins - red - violet colours
How do nectar guides work?
guide pollinator towards reproductive organs and reward. Colour in centre is much more distinctive.
What do conical cells do?
tactile and colour cues which bumble bees detect. Allow bees to grip onto tissue. Bees can discriminate against snapdragons without conical cells.
How is irridescence used?
structural colour formed by microstructures on petal surface. Visual cue for pollinators, can discriminate btw rewarded and unrewarded flowers.
How can bees remember the location of a flower?
Using floral electric fields
How have flowers adapted to pollinators using echolocation?
Developed acoustic mirrors, eg Marcgarvia evenia
What is flower constancy?
How honey bees are seen to travel back to the same flower even though they pass other, equally good/better flowers. Darwin suggested because earning to extract nectar from a new species is risky.
2 examples of coevolution of pollinators and flowers
- Diascia flowers evolved oil in 2 spurs. Rediviva bees have developed unusually hairy forelegs to collect oil.
- Darwin’s orchid - extremely long corolla, most likely to be pollinated by moth w v long tounge. 40 years later discovered Hawk moth.
example of deception
Chiloglottis orchid secretes chlioglottone which mimics pheromone produced by female wasps to sexually attract males
What s a pollination syndrome?
Suites of flower traits, eg flower shape,size, colour, odour etc which have evolved in response to NS due to pollinators.
Pollination by: wind beetles bats insects water slugs bees flies ants birds butterflies
Anemophily Cantharophily Chiropterogamy Entomophily Hydrophily Malacophily Melittophily Myophily Mymecophily Orthinogamy Psychophily
What colour flowers do bees usually pollinate?
not red, see blue, green and UV light do often go for yellow, blue or white flowers.
why would flowers change colour
Dynamic signals allow flowers to change colour if not enough pollen is received, so can attract different pollinators
What other rewards do pollinators seek?
Nursery eg figs for wasps
heat eg skunk cabbage
example of plant mimicry
- Disa nervosa (orchid) doesnt actually contain reward but mimics Watsonia densiflora (rewarded iris)
- S Africn Daisy mimics insect shape and colouring, spots reveal UV colouring similar to female beesbody
- Mirror Orchid - sexual deception. attracts male scoliid wasps.
Why is outbreeding less easy in plants than animals?
animals have separate male and female individuals
flowers often have both make and female parts, so increased inbreeding. can cause inbreeding depression.
what is the result of an inbreeding depression?
reduced biological fitness
Less seeds in self pollinated fruits
eg Banksia spinulosa - 63% decrease in seed set, smaller seed size and fruit set and quality.
How can plants ensure outcrossing?
- timing eg Erythronium grandiflorum staggers pollen release by opening flowers in an order to increase pollinator variation.
- Morphology - stigma can be higher than anthers so unlikely for pollen to fall onto stigma
- Develomental - temporal separation of male and female organs
- Biochemical - SI self incompatability systems
