THEME 4C SPECIATION

Question 1

BIOLOGICAL SPECIES CONCEPT DEFINITION OF A SPECIES

Answer 1

if they are able to exchange genetic material by producing a fertile offspring

Question 2

Why is a species the key evolutionary unit?

Answer 2

• key evolutionary unit because:
• it is the species that becomes extinct, not population
• species gives rise to new species

Question 3

Reproductive isolation, as per BSC

Answer 3

incapable of producing an offspring

incapable of producing a fertile offspring

Question 4

Morphospecies concept

Answer 4

Members of the same species look alike

Question 5

3 Disadvantages of Morphospecies concept

Answer 5

polymorphism could exist within a species

no evolutionary basis or genetic justification

organisms could look alike, but are not actually from the same species

Question 6

Ecological Species Concept

Answer 6

2 different nutritional needs, 2 different lineages of species

Question 7

Evolutionary Species Concept

Answer 7

members of the same species share a common ancestor and fate

Question 8

Disadvantage of Evolutionary Species Concept

Answer 8

How common should this ancestor be for them to be deemed members of the same species?

Question 9

Advantage of Morphospecies Concept

Answer 9

Practical, simple to use

Question 10

Advantage of BSC

Answer 10

clear criteria

Question 11

Disadvantage of BSC

Answer 11

hard to distinguish in the field. Theory-wise, it’s good.

But, in practice, it is not.

Question 12

Advantage of Evolutionary Species Concept

Answer 12

Good for studying asexual organisms

and extinct organisms

Question 13

Which species concept will be correct for all groups?

Answer 13

None. Not one species concept is correct for all groups

Question 14

Process of Speciation

Answer 14

Start with one species

Then a genetic variant spreads. This genetic variant enables the organism to only mate with a member of the same species with the same variant

2 species eventually results from this

Question 15

2 FACTORS THAT LEAD TO REPRODUCTIVE ISOLATION

Answer 15

1) pre-zygotic factors

2) post-zygotic

Question 16

Pre-zygotic

Answer 16

factors that cause reproductive isolation before fertilization

Question 17

5 Types of Pre-zygotic Mechanisms and describe.

Answer 17

Mechanic Isolation: parts don’t fit

Temporal Isolation: separated by time. One is nocturnal, the other isn’t.

Gametic Isolation: Gametes can’t fuse, zygote doesn’t form

Behavioural Isolation: Don’t recognize behaviour (i.e. courtship,etc.)

Habitat Isolation: never meet never mate

Question 18

3 Types of Post-zygotic Mechanisms and describe.

Answer 18

Reduced hybrid viability: dies before it matures

Reduced hybrid fertility: unable to reproduce, sterile

Hybrid breakdown: Offsprings of the hybrid die before they mature
i.e. hybrids can reproduce, but will have unviable offspring

Question 19

Speciation and reproductive isolation are products of ____

Answer 19

genetic divergence

Question 20

Partially Reproductively Isolated

Answer 20

When 2 members of different species that have genetically diverged can produce a inviable or infertile offspring

Question 21

2 Modes of Speciation

Answer 21

Allopatric and Sympatric Speciation

Question 22

Allopatric Speciation

Answer 22

2 species that have formed from one original species due to a geographical separation between the population

Question 23

Subspecies

Answer 23

Species that are NOT partially reproductively isolated, but have, overtime, accumulated traits that are population-specific (i.e. not seen in other populations of the same species)

Question 24

3 ways to become allopatric

Answer 24

Dispersal

Vicariance

Adaptive Radiation

Question 25

Dispersal

Answer 25

Individuals of a population colonizes a distant place

Important in peripatric speciation

Question 26

Peripatric speciation

Answer 26

splitting from the mainland population

Question 27

2 factors why this new population will have faster evolutionary changes than the mainland population?

Answer 27

Small population–> genetic drift more pronounced

New environment –> natural selection also acts very quickly

Question 28

Vicariance

Answer 28

Geographic barrier that arises in a population, and separates it.

I.e. volcano, mountains, blah blah

Question 29

Common outcome of vicariance and dispersal

Answer 29

both will result in two populations that genetically diverge until speciation occurs

Question 30

Adaptive radiation

Answer 30

Unusually rapid diversification, as natural selection accelerates the rate of speciation

Question 31

Why does adaptive radiation occur?

Answer 31

This is due to many opportunities for ecological exploitation

Question 32

Explain the finches adaptive radiation example.

Answer 32

Mainland: finches had to have a certain size of beaks. They cannot have small beaks, as they will be outcompeted by small-seed-eating birds. They cannot large beaks, as they will be outcompeted by large birds. Selection favoured medium-beaks

Galapagos: finches had much that were available to them, there was so much unused resources for small and large beaks, but not for medium beaks. Selection favoured extremes

Question 33

Co-Speciation

Answer 33

A form of allopatric speciation, without the need for geographic speciation. Using hosts.

Two groups of organisms speciate in response to each other.

Question 34

Example of Co speciation. Sympatric or Allopatric speciation?

Answer 34

Parasites can undergo allopatric speciation, when their hosts are separated and forms 2 different species.

For example, when a population of hosts is split into two, separated by geographic barrier, the parasites also undergo allopatric speciation, as they co-speciate with the hosts.

Question 35

Sympatric Speciation

Answer 35

Speciation that occurs, even if they are not geographically separated

Question 36

2 ways sympatric speciation can occur

Answer 36

Disruptive Selection

Instantaneous Selection

Question 37

Disruptive Selection

Answer 37

Since sympatric speciation, they share a common environment and gene flow is possible.

For speciation to occur, disruptive selection must act strongly against the hybrid –> reduced fitness –> reduced viability or fertility

Question 38

Instantaneous Selection- Polyploidy

Answer 38

Offspring of members of the same species has some sort of mutation that renders them reproductively isolated from its parents’ species.

The offspring then can reproduce with other offspring that have the mutation, yielding a new species

Question 39

Speciation by hybridization

Answer 39

Hybridized offspring is fertile and can reproduce with each other, yielding a new species.

See sunflowers.

Question 40

Autopolyploid

Answer 40

An offspring with a polyploid number produced from parents of the SAME species

Question 41

Genetic divergence

Answer 41

accumulation of genetic differences between two populations

Question 42

4 Factors that had caused Genetic Divergence Between Isolated Populations

Answer 42

Genetic Drift due to small pop

Mutations

Selection

Founder effect

Question 43

Allopolyploidization

Answer 43

Offspring undergoes Allopolyploidization, when members of 2 closely related species mate, resulting in an offspring with different number of chromosomes from their parents species (both closely-related species)

Question 44

How does adaptive radiation apply to sympatric speciation?

Answer 44

These new species can have traits that are advantageous for them to exploit unused resources in their environment.