speciation in a ring

Question 1

ring species definition

Answer 1

• ring of populations with a single species boundary

- in ring species space can represent time

Question 2

greenish warbler

Answer 2

-an example of ring species as they differentiate as we move along the ring, only to become more similar when we reach the end of the ring (part closest to the beginning), where the barrier began

Question 3

what changed as we went around the ring?

Answer 3

width of wing bar became larger

Question 4

how did they compare the ring species? what method?

Answer 4

amplified fragment length polymorphism (AFLP), used to examine variations in DNA

Question 5

which forms were most different genetically?

Answer 5

• siberian forms
• siberian and north asian are distinct species, suggesting two expansions from south to north, going around the mountain range

Question 6

ecological speciation

Answer 6

process by which barriers to gene flow evolve between populations as a result of ecologically-based divergent selection
-ie, darwin’s finches beaks adapt base of seed type

Question 7

non-ecological speciation

Answer 7

• can occur due to intraspecific social competition
  1) absence of a single optimum advantage
  2) novelty most favoured
  3) mutually accelerating evolution of preferences and traits

Question 8

two possibilities for origin of premating isolation in green warblers

Answer 8

• ecology first-divergent natural selection leads to correlated changes in mate choice (not possible, due to similarities of east and west)
• or sexiness first- mate-selection traits diverge due to changing sexual selections, mutation, and drift (also busted)

Question 9

ecological factors for green warblers

Answer 9

-habitat differs mainly between north and south, less between east and west

Question 10

song differences

Answer 10

• most similar in the south
• south west more similar to north west, same with south/north east
• length and complexity and time spent singing increased further north

Question 11

songs serve two functinos

Answer 11

mate attraction and territory defense

-mating songs are longer, more complex, while territorial songs are short and simple

Question 12

why are songs more complex as go further north?

Answer 12

• use more sexual songs to find mates, as its harder to find mates with lower pop density, greater vegetation density, and shorter breeding seasons
• lower cost of singing due to more food and longer day length

Question 13

greenish warbler divergence due to neither ecology first or sexiness first

Answer 13

• parallel eco changes lead to parallel selection on mate-selection traits, leading to reproductive isolation
• in other words they adapt differently to the same conditions, leading to divergences genetically
• also, large reproductive isolation in northern contact zone consistent with phenotypic patterns