Lecture 11 - Macroevolution

Question 1

What is irreducible complexity?

Answer 1

• a system composed of several parts that all contribute to a function
• removal of any part causes the system to cease functioning

Question 2

What is the rebuttal to irreducible complexity?

Answer 2

• pieces of complex systems often have functions of their own
• “making a simpler mouse trap”

Question 3

What is an example of a rebuttal against reducible complexity argument?

Answer 3

• bacterial flagellum (basal body)
• made of parts that could serve other functions
• can function if parts are missing

Question 4

What is another example against reducible complexity?

Answer 4

-eyes

Question 5

What does “the evolution of new species is rarely if ever observed” mean as a critique of evolution?

Answer 5

-we never see it happen

Question 6

What are 2 major rebuttals against the claim that new species are never observed?

Answer 6

1. too little of time to observe origin of new species (<0.0066% of biological history)
2. we HAVE observed origin of new species
   (in lab, polyploidization, naturally without polyploidization)

Question 7

What is punctuated equilibrium?

Answer 7

• periods of evolutionary stasis interspersed by major change
• (nothing, then sudden change)

Question 8

punctuated equilibrium is not explained by ___________

Answer 8

Darwinian Theory

Question 9

What did Darwin’s theory believe in instead of punctuated equilibrium?

Answer 9

gradualism

Question 10

What are 3 rebuttals to punctuated equilibrium?

Answer 10

1. punctuations that appear abrupt in fossil record may take tens of thousands of years
2. periods of apparent stasis may fail to give a true impression of biochemical changes not detectable in fossil record
3. slight genetic changes may result in phenotypic changes

Question 11

Sometimes changes at a single ______ can cause _______

Answer 11

gene, speciation

Question 12

In many cases, what is the origin of large phenotypic changes?

Answer 12

evolution of genes controlling development (evo-devo)

Question 13

What is heterochrony?

Answer 13

changes in rate and timing

Question 14

What does heterchrony include?

Answer 14

• changes in relative growth rates of different body parts (allometry)
• changes in timing of reproductive vs. somatic development

Question 15

What does relatively rapid reproductive growth result in?

Answer 15

paedomorphosis

Question 16

What is paedomorphosis?

Answer 16

sexually mature adults with juvenile morphology

Question 17

What is allometry?

Answer 17

changes in relative growth rates of different body parts

Question 18

Changes is allometric growth lead to differences between what 2 species?

Answer 18

human and chimp adult skulls

Question 19

What is an example of a paedomorphic pet? What are its qualities?

Answer 19

• dogs
• relative to ancestral wolves domesticated dogs have:
  1. softer fur
  2. larger head/eyes
  3. droopier ears
  4. more submissive behavior
  5. shorter muzzle

Question 20

Alteration in ______ controlling the placement and organization of _____ _______ cause major _______ change

Answer 20

genes, body parts, evolutionary

Question 21

what are homeotic genes?

Answer 21

genes that control body plans

Question 22

How do homeotic genes work?

Answer 22

They control the developmental fate of groups of cells

Question 23

What are Hox genes? What do they provide?

Answer 23

• products of one class of homeotic genes

- positional information in animal embryos

Question 24

What is an example of Hox genes controlling evolution?

Answer 24

• fish fins to tetrapod limbs

- suppresses leg formation in insects but not crustaceans

Question 25

What are 5 hallmarks of macroevolution?

Answer 25

1. evolution is not goal oriented 2. evolution is not a ladder from simple to complex 3. novel features often arise through intermediate stages (each serving a function) 4. evolution recycles features and put them to new uses 5. evolution leaves baggage behind

Question 26

What does it mean that evolution is not goal oriented?

Answer 26

- mutations are random - selection "chooses" mutations that increase reproduction/survival - evolution gropes blindly in many directions at once

Question 27

What was the old view of evolution? Ladder or tree?

Answer 27

ladder from one-hole to two-holes

Question 28

What was one of the first organisms that was discovered having a complex digestive system?

Answer 28

ctenphora

Question 29

All organisms evolved from a ______ _________

Answer 29

common ancestor

Question 30

What is an example of novel features arising through intermediate stages?

Answer 30

partial wings (they can be adaptive)

Question 31

What is an exaptation?

Answer 31

many characters evolved for purposes other than those for which they are currently used

Question 32

What are 3 examples of exaptation?

Answer 32

1. feathers evolved for insulation, co-opted for flight 2. protein used for cell adhesion in multicellular organisms first evolved in singled celled choanocytes 3. ancient angae had genes for survival on land before they left for water and colonized land

Question 33

What are 3 examples of human evolutionary baggage?

Answer 33

1. appendix 2. trachea 3. blind spot

Question 34

What are the 3 major criticisms of macroevolution?

Answer 34

1. irreducible complexity 2. no observations of speciation 3. punctuated equilibrium inconsistent with Darwin

Question 35

What are the 2 roles of "evo-devo" in driving large changes?

Answer 35

1. changes in rate and timing | 2. changes in spatial pattern