Lecture 1: History of Speciation Research

Question 1

What is speciation?

Answer 1

the evolutionary process by which new biological species arise

Question 2

How does speciation arise?

Answer 2

changes in ecology, mate choice, often through geological separation

Question 3

Define allopatric populations

Answer 3

geographically separated

Question 4

define sympatric populations

Answer 4

overlap geographically

Question 5

What are reproductive isolating barriers?

Answer 5

biological features of organisms that impede the exchange of genes with members of other populations

Question 6

give examples of reproductive isolating barriers

Answer 6

behavioural traits, don’t look like the same species, genetic mechanisms

Question 7

What are naturalists always interested in explaining?

Answer 7

patterns of biodiversity

Question 8

What did early naturalists believe?

Answer 8

species were created long ago by God at once and we’re continually losing species (species creation ended in the Garden of Eden)

Question 9

How did Darwin change everything?

Answer 9

believed species are evolving and change over time which leads to the creation of new species, controversial at the time as it went against Western religion

Question 10

What are the 3 phases of species?

Answer 10

1. origin of species
2. modern synthesis
3. now

Question 11

What happened in phase 1

Answer 11

Darwin’s origin of species released, but it focused more on change within species than the origin of new species but Darwin recognized species evolve and divide

Question 12

what 2 schools of thought did Darwin’s successors have?

Answer 12

1. naturalists, though Darwin focused too much on sympatric species but agreed that NS was the most important speciation force
2. mutationists, rejected Darwin’s claim that speciation is gradual and driven by NS, argued speciation is separate from selection and it actually involves nonadaptive and macromutational leaps

Question 13

Why did speciation research languish

Answer 13

absence of conclusive evidence for 1 theory (gradualism or mutationism)

Question 14

What happened in phase 2?

Answer 14

Dobzhansky, a naturalist and geneticist went back to Darwin’s original ideas by publishing “A Critique of the Species Concept in Biology”, saw how a continuous evolutionary process (change in allele frequencies) could produce genetically and morphologically discrete groups living in 1 habitat

Question 15

Which Darwin’s notion of speciation did Dobzhansky see was incomplete?

Answer 15

ecologically distinct forms cannot coexist without barriers to gene flow, stressed the importance of reproductively isolating mechanisms

Question 16

Who did the first rigorous genetical studies of reproductive isolation

Answer 16

Dobzhansky, when he published “Genetics and the Origin of Species”

Question 17

What is the biological species concept?

Answer 17

groups of interbreeding populations that are reproductively isolated from other groups and it argues that species arise only from allopatric populations

Question 18

Whose ideas stimulated research and shaped our current view of speciation?

Answer 18

Mayr

Question 19

What is a drawback of Modern Synthesis?

Answer 19

focused on reproductive isolating barriers but not on how reproductive isolation evolves

Question 20

true or false: Dobzhansky and Mayr were both naturalists but neither pursued research connecting adaptations to speciation

Answer 20

true

Question 21

what did theoretical and experimental geneticists focus on?

Answer 21

changes within species rather than the origin of new species

Question 22

What was the most glaring omission in Modern Synthesis?

Answer 22

ethological isolation

Question 23

What is ethological isolation?

Answer 23

differences in sexual preferences between species that prevent them from mating

Question 24

What happened in phase 3?

Answer 24

MJ West-Eberhard was the 1st to emphasize the link between sexual selection and speciation

Question 25

When and how did phase 3 begin?

Answer 25

early 80s, new molecular tools allowed novel and more powerful approaches to old questions

Question 26

What did evolutionary biologists realize in phase 3?

Answer 26

ecological approaches to speciation had been neglected during Modern Synthesis, which highlighted the importance of long-term field studies

Question 27

What are the 5 important themes in recent research?

Answer 27

1. Continuation of genetic approaches 2. Mathematical theory 3. Emphasis on ecology 4. Molecular analysis 5. Comparative studies