Lecture 8 - Behaviour and Speciation

Question 1

Species may arise because…?

Answer 1

Populations of a founder species become isolated, either geographically (allopatric, peripatric, parapatric) or behaviourally (sympatric)

Question 2

What is post-isolation?

Answer 2

even if new species re-encounter one another, they remain reproductively isolated

Question 3

Speciation is an… process?

Answer 3

Ongoing

Question 4

What is speciation?

Answer 4

different populations undergo independent divergence maintaining separate identities, evolutionary tendencies and fates.

Question 5

What does speciation form?

Answer 5

the bridge between the evolution of populations and the evolution of taxonomic diversity. The diversity of organisms is the consequence of cladogenesis.

Question 6

What is the study of speciation based off of and why?

Answer 6

Speciation is largely based on inferences from living species as is often too fast to be documented in the fossil record but too slow for us to study as it occurs.

Question 7

As per Coyne and Orr (2004), species can be defined in a way that:

Answer 7

• enables us to classify organisms systematically,
• corresponds to discrete groups of similar organisms,
• helps us to understand how discrete clusters of organisms arise in nature,
• represents products of evolutionary history,
• applies to the largest possible variety of organisms.

Question 8

What is the phenotypic species concept?

Answer 8

“A species is a set of organisms that are sufficiently similar to one another and sufficiently different from members of other species.”

Question 9

What is Bergmann’s Rule (1847)?

Answer 9

“Within a broadly distributed taxonomic clade, populations and species of larger size are found in colder environments, while populations and species of smaller size are found in warmer regions.”

Question 10

What is a species according to the Biological Species Concept?

Answer 10

• A reproductively isolated population.
• “Species are groups of interbreeding natural populations that are reproductively isolated from other such groups.” (Mayr, 1942; 1969:26)

Question 11

What is the problem with the biological species concept?

Answer 11

The BSC does not require that species be 100% reproductively isolated—there can be a little genetic “leakage” between species through hybridization.

Question 12

What are the barriers to gene flow?

Answer 12

• Gene flow between biological species is largely or entirely prevented by biological differences that are referred to as isolating mechanisms, isolating barriers or barriers to gene flow.
• Under the biological species concept, species (the origin of two species from a common ancestral species) consists of the evolution of biological barriers to gene flow.

Question 13

What are the two barriers to the development of species?

Answer 13

Pre-zygotic and post-zygotic

Question 14

What are pre-zygotic barriers?

Answer 14

prevent (or reduce the likelihood of) transfer of gametes to members of another species.
- Ecological isolation.
- Behavioural isolation.
- Post-mating pre-zygotic barriers.

Question 15

What are post-zygotic barriers?

Answer 15

consist of reduced survival or reproductive rates of hybrid zygotes.
- Hybrid unviability.
- Hybrid sterility.

Question 16

What are the two kinds of pre-zygotic barriers?

Answer 16

• Pre-mating
• Post-mating

Question 17

What are the different kinds of pre-mating?

Answer 17

• Ecological isolation
• Limited dispersal
• Isolating behaviour
• Sexual selection and speciation
• Behavioural isolation

Question 18

What are the two kinds of ecological isolation?

Answer 18

Seasonal and habitat isolation

Question 19

What are the four types of how species form?

Answer 19

1. Allopatric
2. Peripatric
3. Parapatric
4. Sympatric

Question 20

What is allopatric species formation?

Answer 20

Geographic speciation, when populations of the same species become isolated and hence form into new species.

Question 21

What is peripatric species formation?

Answer 21

Closely related species in an isolated, nearby but unconnected, area.

Question 22

What is parapatric species formation?

Answer 22

Adjacent ranges with a narrow contact zone so species form in a new area.

Question 23

What is sympatric species formation?

Answer 23

Evolution of new species within the same habitat due to reproductive isolation.

Question 24

Example of allopatric speciation

Answer 24

Darwin’s Finches
- Live on different islands
- Some specialised on plant eaters or eating insects

→ reproductively isolated

Question 25

Example of peripatric speciation

Answer 25

Brown bears and Polar bears

• Tracing the polar bear matriline.
• A matriline is a line of descent from a female ancestor to a descendant (of either sex) in which the individuals in all intervening generations are mothers.
• This diagram shows three hypothetical ideas for the relationships between polar bears and brown bears.