Lecture 11

Question 1

Conclusions from studying life history

Answer 1

1) Life on Earth evolved in response to physical changes
2) Life changed in response to itself
3) Not all developments were progressive or led to further diversity

Question 2

1) Life on Earth evolved in response to physical changes

Answer 2

• Formation of ozone layer that shielded life from UV radiation
• Movement of continents
• Volcanic eruptions, asteroid impacts
• changing ocean chemistry

Question 3

2) Life changed in response to itself

Answer 3

• endosymbiotic origin of eukaryotes
• insects and angiosperms
• duplication of Hox genes and diversity of animal body plans

Question 4

3) Not all developments were progressive or led to further diversity

Answer 4

• There have been many major extinction events that temporarily decreased diversity, including an extinction event we are witnessing today
• The overall trends though is an increase in diversity of organisms over time