Lecture 6: Mechanisms and rates of speciation I

Question 1

traditional view of speciation

Answer 1

• categorised into four different types
• -allopatric
• -peripatric
• -paraptric
• -sympatric
• – now understood can be more than one of these

Question 2

peripatric =

Answer 2

satellite group forming

Question 3

parapatric =

Answer 3

continuum

Question 4

contributors to speciation

Answer 4

• chance
• ecology
• reinforcement
• sexual selection

Question 5

chance

Answer 5

• low-term drift can lead to Dobzhansky-Muller incompatibilities
• mutation order speciation
• founder effect speciation (peripatric speciation)
• polyploid speciation

Question 6

mutation order speciation

Answer 6

populations diverging into similar ecosystems, but different mutations result in different adaptations
-different genetic solutions to same ecosystems

Question 7

polyploid speciation

Answer 7

• common in plants
• instantaneous knew species
• diff. no. of chromosomes so instantly new species

Question 8

polyploid

Answer 8

when u have several copies of a chromosome

Question 9

advantages of polyploid speciation

Answer 9

• heterozygote advantage
• extreme phenotype traits
• reproductive isolation
• duplication on a big scale

Question 10

ecology factors leading to speciation

Answer 10

• environmental differences
• ecological interaction
• sexual selection

Question 11

ecology and Timena cristinae

Answer 11

• 2 ectomorphs
• each have different host
• but can they breed?
• – switch over and put on different host plant - become inviable

Question 12

Howea palms:

Answer 12

• sympatric speciation
• 2 types of palm tree (thatch + curly)
• v genetically similar
• only 5 adult hybrids have ever been found
• isolated by:
• -different habitats (soil) but v close together
• different flowering times

Question 13

Ecological interactions normally occur in

Answer 13

sympatry

Question 14

ecological interactions are normally ___

Answer 14

frequency dependent

Question 15

Ecological interactions can cause

Answer 15

Ecological Character Displacement

–one species shoves other out of niche

Question 16

interspecific competition

Answer 16

occurs between species

-brook & ninespine stickleback

Question 17

infraspecific competition

Answer 17

within one species

Question 18

reinforcement:

Answer 18

often thought of as a mechanism to ‘finish’ the speciation process

• when species in sympatry favours different traits to keep species apart
• cascade reinforcement–start of new speciation

Question 19

reinforcement acts to prevent gene flow but,..

Answer 19

reinforcement needs gene flow initially, but not too much,
balancing act
-enough gene flow for hybrids to exist and be selected against

Question 20

ecological divergence is big driver of

Answer 20

isolation, but must be followed by assortative mating