Rates of Evolution

Question 1

What are the theories of Punctuated Equilibrium & Phyletic Gradualism? Is either of them “right”? Do we see a higher prevalence of either stasis or gradual change?

Answer 1

Punctuated Equilibrium: morphological changes happen during speciation events

Punctuated Gradualism: morphology is constantly changing at gradual rates

No, but we see more examples in punctuated equilibrium because stais is well established in the fossil record. Easier to see stasis than gradualism.

Question 2

Give an example of adaptive radiation and understand the processes that lead to adaptive radiation

Answer 2

Gained novel traits and diversified to fill ecological niches or by finding a new area and filling those niches

Question 3

What’s the difference between competitive and noncompetitive biotic replacement?

Answer 3

Competitive: two species are competing and one outcompetes the other

Non-competitive: there is no competition because one dies out.

Question 4

What mechanism(s) might lead to stasis in a particular clade?

Answer 4

Stabilizing selection: the phenotypic condition being selected for will stay consistent.

Question 5

True or False: Is there a correlation between genome size and mutation rate?

Answer 5

True

Question 6

Are mutation rates consistent over time? Is it ever advantageous to increase the mutation rate?

Answer 6

No, but some are consistent. You would need to test for it. yes, because not all mutations are bad.

Question 7

Which mechanisms might lead to a pattern of punctuated equilibrium?

Answer 7

Biotic Replacement: one clade disappears from the fossil record and another clade takes its place

Adaptive Radiation: small clade diversifies to occupy a wide variety of ecological niches

Question 8

How can we date a phylogenetic tree? Do fossils and molecular clocks give you similar estimates? Why not?

Answer 8

Fossil calibrations and molecular clocks. No, molecular clocks are older than fossils because their mutations have persisted over time.

Question 9

Based on the findings of Louca & Pennell (2020), what’s the risk in estimating a diversification scenario for a clade that has no fossil data?

Answer 9

They’re not linear and happen at different rates over time so its inaccurate.