Evolution Part 2

Question 1

what did Dawkins mean by “selfish gene”?

Answer 1

The genes that better equip us to survive are the ones that are maintained

Question 2

sociobiology

Answer 2

genes associated with behaviour; the primary units upon which natural selection acts; “selfish genes”

Question 3

adaptations

Answer 3

• traits associated with highest relative fitness in a given environment
• Natural selection is the process through which adaptations arise
• Other forces could give rise to adaptations, including chance

Question 4

Influence of habitat on guppies

Answer 4

• Different predators between locations -> natural selection would favour different characteristics (location dependent)
• Differences in habitat creates differences in guppies: colour, number, and size of offspring -> helps them survive predation
• Also creates different anti-predator behaviours

Question 5

guppy anti-predator behaviours (and environmental influence on them)

Answer 5

• Shoaling/schooling: swimming in a group, measure of group cohesiveness
• • In high-predator environments: stick together, tighter shoaling, bigger numbers (and vice versa in low)
• Predator inspection: moving toward a predator to gain important information, then reporting back to the group
• • In high-predator environments: many quick, cautious inspections (and vice versa in low)
• When guppies transferred environments (high to low predators): initially their behaviour stayed the same, but it changed over time to match low predator behaviour (and vice versa for guppies that naturally went from low to high environments)

Question 6

what does it mean that naked mole rats display eusociality?

Answer 6

• “reproductive division of labour” - only certain members reproduce
• Overlapping generations – individuals from a wide range of generations are alive at the same time
• Communal care of offspring

Question 7

naked mole rat reproduction vs. non-reproduction

Answer 7

• Live in large groups, but only 1 queen and 1-3 males reproduce (other members are not physiologically able to reproduce)
• Non-reproductive members: shorter lifespans, cooperative behaviours – defense against predators, tunnel digging, grooming the queen (altruistic behaviours)

Question 8

altruistic behaviours of non-reproductive naked mole rats

Answer 8

• Altruistic behaviours – helping out the group even though they can’t pass on their genes
• these behaviours occur only with related individuals (kin selection) and NMR’s are highly related! (between siblings and twins on a scale)

Question 9

kinship theory

Answer 9

genetic relatives share many of the same alleles. Due to genetic similarity between kin, expect more altruistic behaviour

Question 10

inclusive fitness of non-reproductive naked mole rats

Answer 10

• Sterile colony members accrue reproductive benefits helping their relatives, helping shared genes to be passed down to the next generation
• however, research has shown that inclusive fitness is not required to explain eusociality

Question 11

mate choice in humans

Answer 11

• Theory: the sex that invests more in the offspring should be “choosier” in mate selection, opting for mates that provide resources for their offspring
• Females generally produce large/more expensive gametes (oocytes), show greater parental investment (internal gestation)
• study showed that cross-culturally, most women put higher value in men’s financial prospects than men put in women’s

Question 12

phylogenic trees

Answer 12

Hypothesis of the evolutionary history of the group under study

Question 13

info used to generate phylogenic trees

Answer 13

• Behaviour
• Fossil record
• Morphological changes
• Genetic analyses -> most common

Question 14

parts of phylogenic trees

Answer 14

• Nodes – points at which the tree splits
• • Interior node: common ancestor
• • Evolutionary change along each branch – common ancestor =/= currently living organism
• Root: common lineage from which all species in the tree are derived

Question 15

homology vs. homoplasy

Answer 15

• Homology: trait shared by 2+ species due to a shared ancestry
• • Ex. Milk production by mammals (shared a common, milk-producing ancestor)
• Homoplasy: trait shared by 2+ species due to natural selection, acting independently on each species (not due to common ancestor)
• • Ex. Convergent evolution in wing structure