Kin selection/speciation (W5-L1)

Question 1

Alturism

Answer 1

Individuals sacrifice their own evolutionary fitness for others

Cannot evolve by individual selection, cheaters would be favored

Question 2

Direct Fitness

Answer 2

Personal reproduction

Question 3

Indirect Fitness

Answer 3

Reproduction by relatives, made possible by an individuals actions

Question 4

Inclusive Fitness

Answer 4

The sum of an individuals reproduction through relatives made possible by indirect action and its own reproduction

In order to have a positive effect on the individual, the benefit of alturism must exceed the cost to the alturist

Question 5

Kin selection

Answer 5

Mechanism of increasing inclusive fitness through apparent alturism

Question 6

Hamilton’s Rule

Answer 6

br>c

b=benefit to the recipient
r=coefficient of relatedness of an alturist recipient
c=cost to the alturist

Question 7

When is alturism more likely to spread?

Answer 7

• benefit to the recipient is great
• cost to altruist is low
• participants are closely related

Question 8

How do you calculate the coefficient of relatedness (r) ?

Answer 8

1) drawn all paths
2) multiply probabilities
3) Add probabilities across paths

Question 9

What assumptions can we make about altruism in respect to Kin selection?

Answer 9

• Altruistic behavior will be disproportionately directed towards close relatives (higher r)
• if individuals disproportionately help kin, they must be able to recognize kin from non-kin

Question 10

Eusociality

Answer 10

Extreme altruism:

1. overlapping generation
2. cooperatives brood care
3. reproductive and non-reproductive castes

Only found in groups that build complex nests, care for larvae for extended periods, large ecological component

Question 11

Speciation

Answer 11

When new species form from mutation, gene flow, genetic drift, natural selection, sexual selection

Question 12

General definition of species:

Answer 12

• species are groups that evolve independently from other such groups (independent evolutionary lineages)
• Individuals of the same species contribute to the same gene pool
• species may consist of several interbreeding populations
• taxonomic distinction “species” is the smallest independent evolutionary unit
• To identify a species is to hypothesize the boundaries of gene flow

Question 13

What is the biological species concept?

Answer 13

Groups of actually or potentially inbreeding organisms that are reproductively isolated from other such groups

Question 14

Reproductive isolation

Answer 14

Absence of gene flow between groups of individuals due to intrinsic features of organisms

Question 15

What are the advantages of Biological species concept?

Answer 15

• focuses on gene flow

- grouping principle clear (i.e. breeding vs nonbreeding)

Question 16

What are the issues with the biological species concept?

Answer 16

• hybridization between good species
• ring species
• asexual organisms don’t interbreed
• populations are often geographically separate
• Fossils

Question 17

Extrinsic Barrier

Answer 17

geographical features like mountains, rivers, ocean, forests that prevent gene flow (geographic isolation)

Question 18

Intrinsic barriers

Answer 18

Genetically based properties of organisms that limit gene flow (reproductive isolation)

Question 19

Prezygotic Barriers

Answer 19

Features that prevent individuals from creating a zygote

ex. Ecological differences, temporal differences, sexual (behavioral) differences, gametic imcompatibility

Question 20

Postzygotic Barriers

Answer 20

features that prevent zygote from developing into a healthy and/or fertile adult

ex. Zygote mortality, hybrid inviability, hybrid sterility, other hybrid problems

Question 21

Allopatric Speciation

Answer 21

When 2 groups of one species are isolated geographically and diverge into separate species

The simplest and most common mechanism of speciation

Question 22

Parapatric Speciation

Answer 22

no specific extrinsic barrier to gene flow

• population is continuous, but it does not mate randomly
• mating with geographic neighbors more often
• divergence occurs from reduced gene flow within the population and variation selection processes

Question 23

Sympatric Speciation

Answer 23

Does not require geographic isolation to reduce gene flow between parts of a population

• exploiting a new niche may automatically reduce gene flow between individuals exploiting another niche
• ex. herbivores insects moving to another plant species