lecture 18

Question 1

what is sexual reproduction?

Answer 1

it involves 2 parents

mitosis and meiosis form gametes (egg, sperm) which carry half chromos of parents and fuse together during fertilization

Question 2

what is asexual reproduction?

Answer 2

1 parent is involved and three is no meiosis in chrome number
offsprings get 100% parent chromos and are genetic repliacas (no crossover, no recombination, no segregation)

Question 3

what is the cost of sex?

Answer 3

it takes time + energy to attract mate
they expose themseves to predation
increase energetic cost of hunting mates and moving to breeding grounds
there’s a risk for sexually transmitted diseases
cost of producing males, males are a bad evolution investment
there’s 50% less genetic transmission
can break up adaptive gene combos, offsprings might becomes less adapted

Question 4

what is the paradox of sex?

Answer 4

tries to find benefits of sexual reproduction which overcomes its costs

Question 5

what is the two-fold cost of meiosis?

Answer 5

sexual females can only contribute 50% of genes while asexual females can contribute 100%

Question 6

what is transmission bias?

Answer 6

where asexuality will be favoured as in an equal number offsprings, asexual females can pass down 2x as many genes

Question 7

how can asexual reproduction positively affect offspring fitness?

Answer 7

it can maintain favourable allele combos as genes will be perfectly transmitted

Question 8

how can sexual reproduction negatively affect offspring fitness?

Answer 8

it can continually recreate unfavourable allele combos/break up favourable combos

Question 9

how can sexual reproduction positively impact offspring fitness?

Answer 9

it can bring together new favorable mutations and eliminate harmful mutation more efficiently like only passes on positive mutations

Question 10

in what scenario is sexual reproduction favourable to asexual reproduction?

Answer 10

if enviros are very variable, then sexual reproduction can create more variable offspring which are more likely to match unpredictable enviro

Question 11

what is tangled bank hypothesis?

Answer 11

the idea the enviro is spatially heterogenous/not uniform through spaces

Question 12

what is the red queen hypothesis?

Answer 12

talks abt temporarily heterogenous enviros, theorizes that if enviro will change in the future producing the same thing repeatedly might not be a good idea
favours variation

Question 13

how can asexual reproduction negative affect offspring fitness?

Answer 13

it can cause accumlation of negative, deleterious mutations through accumulation of premature stop codons

Question 14

where can asexual organisms be found on a phylogeny tree and why?

Answer 14

asexual species are usually at tips of phylogenies, its rare for an entire phylogeny to be asexual, their evolutionary potential in long term may be low due to lack of genetic variation which mayb cause higher extinction rate

Question 15

how to asexual and sexual reproduction differ in advantage type?

Answer 15

asexual reproduction has short term advantage while sexual reproduction has long term advantage

Question 16

what is outbreeding?

Answer 16

mating w/ less closely related than random is outbreeding

Question 17

what is inbreeding?

Answer 17

mating w/ more closely related than random (relatives)

Question 18

what is selfing?

Answer 18

selfing involves 1 parent, there is meiotic division of gametes and fusion of gametes but you fertilize you own eggs aka mating w/ self, this happens in plants where pollen fertilizes ovules of same individual
hermaphoritic organisms (most plants, many animals) self fertilize

Question 19

what is outcrossing?

Answer 19

outcrossing involves 2 parents, meiotic division of games and fusion of gametes and involves mating w/ others

Question 20

what is a local pop substructure?

Answer 20

local pop substructure mean individual found in same location tend to be related so there is high potential for mating w/ close relative

Question 21

what are methods plants use to avoid inbreeding?

Answer 21

large showy flowers are used to attract pollinators

hermaphroditic sepcies have diff timing for male and female reproduce ex. in flowering plantts pollen is mature before stigma are receptive

go through a male phase then a female phase

Question 22

what is self-incompatibility?

Answer 22

genetic/morphological mechanisms used to avoid selfing (fertilization onelft)

Question 23

what are some examples of self-incompatibility?

Answer 23

dispersal which is often sex biased where all individuals of one sex will disperse while other will stay in native home

delayed maturation means offspring will not be sexually active at same time as parents

extra pair copulation where they will have a mate which is not their social partner

additionally there is evidence animals can recognize kin and will avoid them

Question 24

what are the effects of inbreeding on genotype frequency?

Answer 24

inbreeding (non-random mating) changes genotype frequency (A1A1, A1A2, A2A2), increases homozygosity, decreases heterozygosity, but does not change allele frequency (number of A1 and A2 overall)
the more close mates are related, the quicker heterozygous declines
it decreased by 50% per gen through self-fertilization

Question 25

what is inbreeding depression and what doe sit entail

Answer 25

inbreeding depression is reduced fitness in inbred offsprings compared to outcrossed offspring
its shown in reduction in viabilility (survival) and fertility
inbreeding depressing lowers fitness by exposing deleterious negative alleles

Question 26

how do selfing plants evolve?

Answer 26

selfing flowers have reduced petal size and reproductive organs are in close contact w/ each other

Question 27

how do selfing plants evolve?

Answer 27

selfing flowers have reduced petal size and reproductive organs are in close contact w/ each other

Question 28

what’s the fitness of advantage of selfing?

Answer 28

selfing variant has 50% transmission advantage, this might be the major advantage which leads to the evolution of selfing
selfing flowers tend to have larger ranges than outcrossing flowers