Lecture 5

Question 1

What are embryophytes?

Answer 1

Land plants

Question 2

What type of phylogeny is embryophytes?

Answer 2

Monophyletic

Question 3

What is the definition of algae? What type of phylogeny?

Answer 3

• Photosynthetic eukaryotes excluding land plants

- Paraphyletic

Question 4

What is the closest relative to all living land plants?

Answer 4

Charales; likely to be the sister group to the land plants

Question 5

What are Charales?

Answer 5

An order of freshwater green algae within the class Charophyceae

Question 6

When did the land plants originate? Did this count? What did early plants look like?

Answer 6

• Spore-like microfossils are known from middle Cambrian (about 510 ma) but exact affinities unknown
• Spores from embryophytes appear around mid-Ordovician
• Early plants were small and morphologically simple (similar to living mosses and liverworts)

Question 7

When did most of the major groups of land plants originate?

Answer 7

Major radiation- late Silurian-early Devonian (about 400 my)

Question 8

How is the Major radiation similar to the Cambrian Explosion?

Answer 8

1) involved the origin of most major body plans seen in living plants today
2) increase in species richness relatively small compared to increase in phenotypes
3) development of impermeable outer surfaces
4) coincided w/ major environmental changes–> CO2 levels fell and O2 levels rose sharply

Question 9

What consequences followed the evolution of land plants?

Answer 9

• Energy & nutrient fluxes in terrestrial and freshwater ecosystems changes significantly
• Evolution of well developed root systems led to mechanical disruption & acidification of soils
• Led to increased weathering of Ca-Mg silicate minerals