Lec 10: Diversification - Adaptive Radiation

Question 1

describe macroevolution

Answer 1

• over geological time scales

- observed through fossils

Question 2

describe microevolution

Answer 2

• can be observed within a human generation

- observed through genomic work

Question 3

It is difficult to define “complexity” and difficult to determine whether species become more complex through evolution. However, there is a trend in trait evolution. What is it?

Answer 3

• species becoming more specialized over time

become very adapted to a specific habitat

Question 4

Can species regain a trait that is lost through evolution?

Answer 4

it is rare but can happen

Question 5

Define irreducible complexity

Answer 5

traits whose functions are so essential to life, losing them through evolution seems impossible

Question 6

Name examples of key innovations in trait evolution

Answer 6

1) flight
2) hard bodies
3) evolution of seeds

Question 7

define taxonomic rates of evolution

Answer 7

the rate at which taxa evolve

Question 8

What is adaptive radiation?

Answer 8

a rapid speciation and evolution event

Question 9

What causes an abundance of unfilled niches?

Answer 9

• key innovation traits
• formation of new physical spaces
• ecosystem engineering

Question 10

Why did mammal radiation occur after the end-cretaceous extinction?

Answer 10

• loss of dinosaurs = abundance of empty niches

- small size, generalist habitat

Question 11

What led to adaptive radiation in angiosperms?

Answer 11

• experienced extreme adaptive radiation after initial emergence
• Why? because their main role is to attract pollinators. Since insects travel faster than wind-dispersed pollen, angiosperms and angiosperm pollinators co-evolved and both diversified extensively. Some non-angiosperm pollinators switch to angiosperms.
• since angiosperms grow faster than conifers, they pushed out slower growing conifers.
• additionally, their decomposing leaves changed the composition of the soil, making it more neutral and further pushing out conifers.

Question 12

What is gradual speciation?

Answer 12

Gradual speciation gives rise to new species slowly over time.

Question 13

What is punctuated equilibrium?

Answer 13

Punctuated equilibrium occurs when species diverge QUICKLY and then remain unchanged for long periods of time.

Question 14

What are the 2 requirements for punctuated equilibrium to occur?

Answer 14

Must be a mutation that occurs in a short period of time (just severe enough) AND must be reproductive or geographic isolation between ancestral and new species.

Question 15

Which form of speciation is most common?

Answer 15

Gradual speciation

Question 16

What is an example of a species in the fossil record which followed punctuated equilibrium?

Answer 16

The Coelacanth. It experienced rapid evolution after its first appearance in the fossil record, but remained the same for 360 million years after that.