Plant Evolution (Block 6) Flashcards
What were the first instances of herbivory centred around in evolutionary history?
Eating dead plant material.
What was probably the first producer on land before land plants?
Algae, forming algal mats.
What were the earliest food chains on land based on?
Detritovores//algae-eaters, which ate algae and were likely eaten by other animals.
Why are bitten leaves not enough energy for herbivory?
The leaf could already be dead.
What is good evidence for herbivory?
A bitten leaf with a healing response (meaning it is alive).
How did detritivores make the change to herbivory?
Leaves decay gradually, so arthropods gradually evolved to eat leaves that were less and less dead over time.
How did carnivorous animals make the change to herbivory?
They started by eating the occasional plant, and gradually making the switch to omnivores, then carnivores.
How long did it take for herbivores to evolve after the first land vertibrates evolved?
95 million years.
Why was it difficult to evolve herbivory?
> Cellulose is hard to digest.
> Plant chemical defences.
Why might flight have evolved in animals?
> To reach PLANT food.
> To evade predators.
How may the evolution of flight involved plants?
Flight first evolved by launching from a high place and trees provided this height.
Why would animals launch themselves from trees?
> Gravity gets you down faster after climbing.
What benefits would plants get from animals climbing them?
Insects may have dispersed spores by eating them like modern birds disperse seeds.
How did spore consumption by insects aid the seedless vascular plant life cycle?
Usually, sperm from one plant has to swim to another, but an insect could excrete 2 or more plants together, enabling breeding.
How did grass take over?
> Grass has lower growing points, so if it is grazed it will grow back, unlike monocots.
Grass has a uniform silica defence, which grazers can adapt to, whereas monocots have varied chemical defences.
