Evolution Part 2 Flashcards
what did Dawkins mean by “selfish gene”?
The genes that better equip us to survive are the ones that are maintained
sociobiology
genes associated with behaviour; the primary units upon which natural selection acts; “selfish genes”
adaptations
- 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
Influence of habitat on guppies
- 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
guppy anti-predator behaviours (and environmental influence on them)
- 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)
what does it mean that naked mole rats display eusociality?
- “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
naked mole rat reproduction vs. non-reproduction
- 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)
altruistic behaviours of non-reproductive naked mole rats
- 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)
kinship theory
genetic relatives share many of the same alleles. Due to genetic similarity between kin, expect more altruistic behaviour
inclusive fitness of non-reproductive naked mole rats
- 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
mate choice in humans
- 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
phylogenic trees
Hypothesis of the evolutionary history of the group under study
info used to generate phylogenic trees
- Behaviour
- Fossil record
- Morphological changes
- Genetic analyses -> most common
parts of phylogenic trees
- 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
homology vs. homoplasy
- 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
