Adaptations & Traits 2

Question 1

interaction types between species (5)

Answer 1

• competition
• mutualism
• predation
• parasitism
• commensalism

Question 2

why is competition an important evolutionary force

Answer 2

• a large fraction of an individual’s resources may be dedicated to competition against others

Question 3

invasive species (2)

Answer 3

• species that have dispersed to a new area

- species that have been freed from the predator and prey that have evolved adaptations against it, and can then thrive

Question 4

coevolution (2)

Answer 4

• evolution of 2+ species influences by each other through their interactions
• can involved predation, competition, living together, etc

Question 5

what favours the evolution of mutualism/cooperation (2)

Answer 5

• simple, mutual benefit

- entangled fates

Question 6

entangled fates

Answer 6

• if the descendants of interacting lineages have their fates tied together, then that promotes cooperation, regardless of whether there was an initial mutual benefit

Question 7

vertical transmission

Answer 7

• the babies of interacting species also interact

Question 8

how does entangled fates lead to mutualism/cooperation (2)

Answer 8

• given vertical transmission, the parasite cannot take too many resources from the host or the host may die or not have babies
• parasites that reduce fitness will be selected against, and those that are able to cooperate within the host and have offspring passed onto the host offspring will live

Question 9

what occurs during horizontal transmission of bacteria

Answer 9

• as bacterium can jump between hosts in the same generation, its fitness would not depend on the host offspring survival
• become more virulent and select to be able to spread more, even if that kills the host

Question 10

consequences of vertical transmission (2)

Answer 10

• evolution cooperation/mutualism

- co-speciation (parallel phylogenies)

Question 11

how does vertical transmission lead to co-speciation (2)

Answer 11

• if populations of the hosts become isolate, so do the populations of their contained pathogens
• thus, divergence of the hosts is paralleled by the divergence of the pathogens, which will be reflected i their parallel phylogenies

Question 12

symbiosis

Answer 12

• two species living together

Question 13

endosymbiosis example

Answer 13

• mitochondrial ancestors were bacteria that entered eukaryotic cells and stayed

Question 14

entangled fates: mitochondria & eukaryotes (3)

Answer 14

• mitochondrial ancestor were originally parasites: they stole ATP from the cytoplasm and returned ADP
• once inside the cell permanently, they were vertically transmitted and selection for cooperation began
• now, ATP/ADP translocase gets ADP from the cytoplasm and returns ATP

Question 15

entangled fates: aphids and bacteria (3)

Answer 15

• bacteria was originally a parasite: it took resources from the aphid that lowered its fitness
• once inside the cell permanently, they were vertically transmitted and selection for cooperation began
• now, bacteria cooperates with the aphids in mutualistic relationship so that it’s progeny can continue to be passed onto the host’s offspring

Question 16

mutualism: pollination

Answer 16

• pollinators get rewards (nectar, pollen), while plants get pollen transferred to the next plant (bring plant sperm and egg together)

Question 17

predator-prey co-evolution: bat & moth (3)

Answer 17

• bats use echolocation to find prey, such as moths
• bats: disconnect the middle ear bone when making noise to avoid deafening themselves and reconnecting after to hear responses
• moths: have a tympanal organ (evolved 7 times) to fly away when they hear the bats’ echolocation pulses and can emit ultrasonic clicks that jam the bat’s sonar

Question 18

what levels of interaction can occur among lineages? (4)

Answer 18

• among species
• among individuals within species
• along cells lineages within individuals
• along gene loci within cell genomes

Question 19

conflict within individuals of a species (2)

Answer 19

• competition
• “density dependence” in ecology: individual’s success depends on the density of other individuals in the area (usually negative)

Question 20

cooperation within individual’s of a species

Answer 20

• seen in social/colonial organisms

Question 21

cooperative spiders (2)

Answer 21

• cooperation helps colonies to grow and produce more daughter colonies: collectively catch prey, take care of each other’s young
• individuals don’t jump between colonies, so their fates are entangled: be nice to other offspring because your offspring depends on them

Question 22

why don’t spiders “cheat” in cooperative colonies? (3)

Answer 22

• a selfish, cheating trait might spread through the colony, but this colony would not survive or reproduce daughter colonies as well
• if their selfishness harms their colony-mates, they also harm their own offspring because their fates are linked in future generations
• only if individuals could jump between colonies would selfishness win

Question 23

cooperation along cells within an individual

Answer 23

• multicellular organism is a colony of cells, with specialization

Question 24

are there cheaters within colonies of cells (multicellular organisms) (2)

Answer 24

• yes, selfish (cancer) cells can take over within an individual
• these cells won’t succeed over evolutionary time because the body will die, and the selfish cells will die with it (fates of all cells within individual are entangled)

Question 25

cooperation among genes within a genome (2)

Answer 25

• each set of genes cooperates within the genome to build a body
• the fate of the genes are shared: in order to survive/pass on offspring, they must succeed in building the body

Question 26

how could a gene locus cheat/be selfish within a genome (2)

Answer 26

• gene duplication
• too much gene duplication would kill the organisms and itself, but there is a low level of cheating as these events have led to diversity in our genome

Question 27

gene duplication (2)

Answer 27

• duplication of a gene and insertion of the second copy into another area of the genome
• gene at the original site can continue its usual function, but the extra copy can evolve to a new function/disappear/or be non-functional

Question 28

transposable elements (3)

Answer 28

• sequences of DNA that can move within and between genomes
• selfish: they don’t normally perform useful functions, but persist because they have succeeded in replicating themselves
• not intrinsically good or bad

Question 29

how do genomes get so big

Answer 29

• lots of transposable elements: quantity of protein coding exons is fairly constant among eukaryotes, but quantity of transposable elements varies widely

Question 30

conflict within the genes among the genome (2)

Answer 30

• transposons can have deleterious effects: metabolic costs of maintaining DNA, new mutations when moving, etc
• what is good for transposons is often bad for the host

Question 31

what are the requirements for selection at different levels? (4)

Answer 31

1. competition: more ______ are produced than can be supported by the available resources
2. variation: there is variation among ______ in survival and reproduction that depends on their traits
3. inheritance: some of this variability is inherited; an ______ tends to look like its parents

where ______ could be gene copies, cells, individuals, colonies, or species

Question 32

what is the outcome of evolution according to the multilevel selection perspective

Answer 32

• outcome is determined by the balance of selective forces at different levels

Question 33

when does cooperation evolve

Answer 33

• when it is advantageous