Lecture 18 - Variability Selection

Question 1

Temperature Proxy (using O18) through Geological time

Answer 1

overall temperature drop from paleocene to holocene, with slight spike in miocene (not as high as eocene)

Question 2

natural selection

Answer 2

differential reproduction (and survival) of individuals due to differences in traits
* one of several mechanisms of evolution

Question 3

natural selection occurs when:

Answer 3

• populations are variable in their traits (mutations, genetic drift, gene flow)
• variation is heritable
• competition

Question 4

types of natural selection

Answer 4

directional: one direction
diversifying: two directions
stabilizing: narrowing

Question 5

specialization

Answer 5

the process of evolving traits to efficiently use a particular resource
- specialiasts can outcompete generalists in a specific environment but not general environment

Question 6

variability selection

Answer 6

= climate variability increases through time, rather than direction selection, VS postulates that increased variability introduces new selective pressures, generalist traits evolve when rapid variation occurs

Question 7

plant biomarkers

Answer 7

• leaves are covered in wax
• wax contained biomarkers
• only produced by plants
• readily distinguishes from other geological chemicals
• Sea-cores can be used to directly reconstruct vegetation isotopic ratios

Question 8

sapropels

Answer 8

• dark colored ocean sediments, very rich in organic matter
• record from Mediterranean cores informs about Nile flow
• darker, richer sapropels indicate more precipitation, organics from Nile
  informs about flow of Nile