Evo Bio Final Study Guide

Front 1

What is altruism?

Back 1

Interactions between individuals of a species/population in which the individual instigating the act of helping another individual pays a cost of reduced fitness, while the recipient benefits by increased fitness.

Front 2

How does altruistic behavior present a problem for evolution by natural selection?

Back 2

Altruistic behavior increases the chances that the individual will die because it makes the individual more vulnerable and apparent to prey. If the individual dies, then it cannot pass along its genes.

Front 3

Be able to understand Haldane's comment "I would lay down my life to save two brothers, but not one; or to save eight cousins, but not seven."

Back 3

probability that siblings share mom's genes= ½ * ½ = ¼

probability that siblings share same genes= ¼ (mom) + ½ (dad) = ½

cousins share 1/8 of their genes (on average)

Front 4

Understand Haldane's rule: Br - C > 0

Back 4

B= benefit (measured in surviving offspring)

r= relatives

c=cost

Br – c > 0 or Br > c

kin selection causes genes to increase in frequency when the genetic relatedness of a recipient to an actor multiplied by the benefit to the recipient is greater than the reproductive cost to the actor

Front 5

Inclusive fitness:

Back 5

the fitness of an individual organism as measured in terms of the survival and reproductive success of its kin, each relative being valued according to the probability of shared genetic information

Front 6

what is direct and indirect fitness?

Back 6

-Direct fitness: result from personal reproduction

-indirect fitness: results from additional reproduction by relatives made possible by individual's actions

Front 7

What is kin selection?

Back 7

Selction that favors increase in alleles that improve indirect fitness

Front 8

What are "greenbeard alleles"

Back 8

1. allele has specific phenotype

2. individuals with allele recognize allele in other individuals

3. individuals who share allele act more altruistically toward each other than individuals who don't

Front 9

What is eusociality?

Back 9

-The worker castes do not reproduce but spend their lives caring for the colony, including the eggs and the young produced by the queen. It is an extreme form of altruism.

-What are some examples of eusocial organisms?

-Ants, bees, wasps, naked mole rats

Front 10

What is haplodiploidy? How does it work in eusocial societies?

Back 10

System of sex determination in which males are haploid and females develop from fertilized eggs. (males only contain chromosomes from their mother and females contain chromosomes from both mother and father)

Front 11

What are they three requirements of eusociality?

Back 11

1. overlap in generations between parents and offspring

2. cooperative brood care

3. castes (i.e. classes of individuals) that are non-reproductive

Front 12

What is reciprocal altruism?

Back 12

a behaviour whereby an organism acts in a manner that temporarily reduces its fitness while increasing another organism's fitness, with the expectation that the other organism will act in a similar manner at a later time.

Front 13

What is speciation?

Back 13

-Process by which one species gives rise to another species

giving rise to evolutionarily independent lineages

-(species= smallest evolutionarily independent unit)

Front 14

Morphological species concept

Back 14

similarities in morphology used to group organisms into species

-advantages: -can apply to both sexual and asexual organisms

--does not require knowledge of gene flow/ reproductive barriers

-disadvantages: -very subjective

---limited to only what we can observe

Front 15

biological species concept:

Back 15

set of actually or potentially interbreeding populations whose members can produce viable and fertile offspring

-advantages:

-disadvantage: doesn't work for asexual organisms

Front 16

ecological species concept:

Back 16

group of organisms adapted to a specific set of resources (niche)

-advantage: can use for asexual organisms

-disadvantage: -does not account for gene flow

--things look the same and utilize the same resources but are independent species

Front 17

evolutionary species concept:

Back 17

single evolutionary lineage of organisms which maintains its identity from other such lineages and has its own evolutionary history and fate

-advantage: can apply to sexual and asexual organisms

--looking for gene flow between organisms

--can use different types of data: molecular sequence, morphological, ecological)

--less bias

-disadvantage: have to know evolutionary histories of organisms

Front 18

phylogenetic species concept

Back 18

smallest diagnosable group of organisms that share a common ancestor

-advantage: can apply to sexual and asexual organisms

--looking for gene flow between organisms

--can use different types of data: molecular sequence, morphological, ecological)

--less bias

--can test statistically in DNA between individuals or populations

-disadvantage: have to reconstruct evolutionar

Front 19

genetic species concept:

Back 19

species boundaries are determined by % similarity

-advantage:

-disadvantage: subjective on the % similarity cutoff and what genes we use

--no one gene shared by all organisms

Front 20

What are three stages of speciation (i.e., genetic isolation)?

Back 20

1. isolation of populations (physical, ecological, temporal)

2. genetic divergence

3. reproductive isolation (prevents back flow of diverged alleles during secondary contact)

Front 21

Vicariance:

Back 21

is a process by which the geographical range of an individual taxon, or a whole biota, is split into discontinuous parts by the formation of a physical or biotic barrier to gene flow or dispersal.

Front 22

secondary contact:

Back 22

re-establishment of contact between sister populations after they have diverged

Front 23

hybridization:

Back 23

the process of interbreeding between individuals of different species

Front 24

reinforcement:

Back 24

the process by which natural selection increases reproductive isolation.

Front 25

Prezygotic isolation:

Back 25

reproductive isolation that prevents the fertilization of eggs (include habitat isolation, mating seasons, "mechanical" isolation, gamete isolation and behavioral isolation)

Front 26

postzygotic isolation:

Back 26

reproductive isolation that prevents the formation of fertile offspring (include hybrid inviability, hybrid sterility and hybrid "breakdown.")

Front 27

gametic isolation:

Back 27

gametes of different species meet but do not fuse to form a zygote. Internal fertilization: sperm doesn't survive. External fertilization: gametes don't recognize each other

Front 28

How do flu vaccines work? Why are new vaccines developed every flu season?

Back 28

Flu vaccines work by exposing the patient’s immune system to killed flu viruses. Even though the viruses are dead, the immune system recognizes the viral proteins as foreign, mounts a response against them, and remembers their structure. In the event of a later infection by live viruses, the immune system can respond immediately. It can respond immediately, that is, as long as the hemagglutinin on the live invaders is similar enough to the hemagglutinin on the dead viruses that were in the vaccine. The problem is that flu populations evolve rapidly, and vaccines take months to prepare in large quantities. Vaccine makers must begin production well in advance of the flu season. That means their scientific advisors must try to predict which among recently circulating flu strains are most likely to be responsible for next season’s epidemic, so that they know which strains to include in the vaccine.

Front 29

What are three factors about pathogens that allow them to evolve so quickly?

Back 29

1. large population size 2. short generation time 3. high mutation rate

Front 30

Influenza A

Back 30

has a genome composed of eight RNA strands that encode a total of 13 proteins. These proteins include polymerases, structural proteins, and coat proteins. The predominant coat protein is called hemagglutinin. Hemagglutinin initiates an infection by binding to sialic acid on the surface of a host cell

Front 31

Hemagglutinin

Back 31

the primary protein recognized, attacked, and remembered by the host’s immune system. To stay alive, any given strain of influenza A must either find a steady supply of naive hosts who have never been exposed to its version of hemagglutinin or alter its hemagglutinin so that previously exposed hosts no longer recognize it.

Front 32

Antigenic sites

Back 32

the specific parts of a foreign protein that the immune system recognizes and remembers.

Front 33

What have we learned about influenza evolution by sequencing the hemagglutinin genes from various flu strains?

Back 33

First, the flu strains accumulated nucleotide substitutions in their hemagglutinin genes at a steady rate, about 6.7 * 10-3 per nucleotide per year. Second, most of the flu samples represent extinct side branches on the evolutionary tree

All 18 of the positively selected codons were for amino acids in antigenic sites of the hemagglutinin protein. It appears that the human immune system does, indeed, exert strong selection on flu virus hemagglutinin genes and that virus populations evolve in response.

Front 34

How can we use what we have learned about hemagglutinin mutations to design more effective flu vaccines?

Back 34

a way to predict which of the currently circulating flu strains is most likely to have surviving descendants in the future. The survivor, they reasoned, is most likely to be the currently circulating strain with the most mutations in the 18 codons known to be under positive selection. On this basis, the researchers were able to accurately “predict,” for 9 of 11 recent flu seasons, which of each season’s strains would be the one to survive while the rest became extinct

the one with the most amino acid replacements in its hemagglutinin antigenic sites is usually the surviving strain