lecture 9 - the power of flowers

Question 1

What contributed to the early success of flowering plants?

Answer 1

Diversification in insects groups coincides with the appearance of flowering plants - subsequently insects and flowering plants co-evolved
The floral designs of early flowering plants (e.g. pollen grains) were very successful & are recognisable 140 million years later

Question 2

Give an ecological explanation for Darwin’s abominable mystery

Answer 2

Early angiosperms were limited to disturbed, aquatic or very dry sites
Gymnosperms dominated the plant world
Angiosperms had higher growth rates and could profit rapidly from increased nutrient supplies - better access to nutrients
Angiosperms promoted soil nutrient release by producing leaf litter that was more easily decomposed - better at shedding leaves so nutrients recycled faster
Once Angiosperms reached a critical level of abundance this feedback resulted in unstoppable process that led to Angiosperm dominance
There is some evidence to support this theory from large scale vegetation shifts, linking long-term field observations, large scale experiments and the use of simulation models

Question 3

How did angiosperms evolve?

Answer 3

The ancestral angiosperm was polyploid
An ancient whole genome duplication predated angiosperm diversification
This provided a large number of genes that survived to play key roles in angiosperm biology
Amborella is sister to all other extant angiosperms

Question 4

Define and explain Darwin’s abominable mystery

Answer 4

Darwin struggled to explain an explosive burst in diversity shortly after the origin of angiosperms
Darwin referred to this as an “abominable mystery”
Insect pollination is ancestral, insects and flowering plants co-evolved
Growth rate and an enhanced ability to access available nutrients gave flowering plants critical advantage
Genome duplication gave flowering plants an additional set of genes for selection

Question 5

Describe the features flowers have evolved to attract pollinators

Answer 5

Pollinator behaviour can be manipulated by colour changes
The colour of Anthocyanidins in part depends upon chemical sub-groups attached to the B ring
Petal cell shape can determine the intensity of petal colour
Pollinator behaviour is influenced by colours, patterns and electrical fields
Pollinator efficiency is manipulated through scents and other chemical attractants